Make the new AndroidKeyStore API conformant.

This makes the new AndroidKeyStore API conform with the latest
Keymaster API changes as well as the latest Android framework API
design guidelines.

Keymaster changes:
* Multiple paddings, block modes, and digests can be set on a key.
* "max uses per boot" and "min seconds between use" restrictions will
  not be exposed in the framework API.
* Padding scheme ZERO will not be exposed.

Changes due to Android framework design guidelines:
* Sets of enum values have been replaced with bitsets represented as
  ints.
* Integer has been replaced with int, with null being represented
  with a special value (e.g., -1 or 0) where possible.

Bug: 18088752
Change-Id: Ib21739aa9b42d48895cb7a681e836a5c6d972ac6

8 files changed, 470 insertions, 698 deletions

diff --git a/keystore/java/android/security/AndroidKeyStore.java b/keystore/java/android/security/AndroidKeyStore.java
index dcc79be..f72c7ac 100644
--- a/keystore/java/android/security/AndroidKeyStore.java
+++ b/keystore/java/android/security/AndroidKeyStore.java
@@ -466,81 +466,72 @@ public class AndroidKeyStore extends KeyStoreSpi {
             throw new KeyStoreException("Unsupported secret key algorithm: " + keyAlgorithmString);
         }
 
-        if ((params.getAlgorithm() != null) && (params.getAlgorithm() != keyAlgorithm)) {
-            throw new KeyStoreException("Key algorithm mismatch. Key: " + keyAlgorithmString
-                    + ", parameter spec: "
-                    + KeyStoreKeyConstraints.Algorithm.toString(params.getAlgorithm()));
-        }
-
         KeymasterArguments args = new KeymasterArguments();
         args.addInt(KeymasterDefs.KM_TAG_ALGORITHM,
                 KeyStoreKeyConstraints.Algorithm.toKeymaster(keyAlgorithm));
 
-        if (digest != null) {
-            // Digest available from JCA key algorithm
-            if (params.getDigest() != null) {
-                // Digest also specified in parameters -- check that these two match
-                if (digest != params.getDigest()) {
-                    throw new KeyStoreException("Key digest mismatch. Key: " + keyAlgorithmString
+        @KeyStoreKeyConstraints.DigestEnum int digests;
+        if (params.isDigestsSpecified()) {
+            // Digest(s) specified in parameters
+            if (digest != null) {
+                // Digest also specified in the JCA key algorithm name.
+                if ((params.getDigests() & digest) != digest) {
+                    throw new KeyStoreException("Key digest mismatch"
+                            + ". Key: " + keyAlgorithmString
                             + ", parameter spec: "
-                            + KeyStoreKeyConstraints.Digest.toString(params.getDigest()));
+                            + KeyStoreKeyConstraints.Digest.allToString(params.getDigests()));
                 }
             }
+            digests = params.getDigests();
         } else {
-            // Digest not available from JCA key algorithm
-            digest = params.getDigest();
+            // No digest specified in parameters
+            if (digest != null) {
+                // Digest specified in the JCA key algorithm name.
+                digests = digest;
+            } else {
+                digests = 0;
+            }
         }
-        if (digest != null) {
-            args.addInt(KeymasterDefs.KM_TAG_DIGEST,
-                    KeyStoreKeyConstraints.Digest.toKeymaster(digest));
+        for (int keymasterDigest : KeyStoreKeyConstraints.Digest.allToKeymaster(digests)) {
+            args.addInt(KeymasterDefs.KM_TAG_DIGEST, keymasterDigest);
+        }
+        if (digests != 0) {
+            // TODO: Remove MAC length constraint once Keymaster API no longer requires it.
+            // This code will blow up if mode than one digest is specified.
             Integer digestOutputSizeBytes =
                     KeyStoreKeyConstraints.Digest.getOutputSizeBytes(digest);
             if (digestOutputSizeBytes != null) {
-                // TODO: Remove MAC length constraint once Keymaster API no longer requires it.
                 // TODO: Switch to bits instead of bytes, once this is fixed in Keymaster
                 args.addInt(KeymasterDefs.KM_TAG_MAC_LENGTH, digestOutputSizeBytes);
             }
         }
         if (keyAlgorithm == KeyStoreKeyConstraints.Algorithm.HMAC) {
-            if (digest == null) {
-                throw new IllegalStateException("Digest algorithm must be specified for key"
-                        + " algorithm " + keyAlgorithmString);
+            if (digests == 0) {
+                throw new KeyStoreException("At least one digest algorithm must be specified"
+                        + " for key algorithm " + keyAlgorithmString);
             }
         }
 
-        @KeyStoreKeyConstraints.PurposeEnum int purposes = (params.getPurposes() != null)
-                ? params.getPurposes()
-                : (KeyStoreKeyConstraints.Purpose.ENCRYPT
-                        | KeyStoreKeyConstraints.Purpose.DECRYPT
-                        | KeyStoreKeyConstraints.Purpose.SIGN
-                        | KeyStoreKeyConstraints.Purpose.VERIFY);
-        for (int keymasterPurpose :
-            KeyStoreKeyConstraints.Purpose.allToKeymaster(purposes)) {
+        int purposes = params.getPurposes();
+        for (int keymasterPurpose : KeyStoreKeyConstraints.Purpose.allToKeymaster(purposes)) {
             args.addInt(KeymasterDefs.KM_TAG_PURPOSE, keymasterPurpose);
         }
-        if (params.getBlockMode() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_BLOCK_MODE,
-                    KeyStoreKeyConstraints.BlockMode.toKeymaster(params.getBlockMode()));
-        }
-        if (params.getPadding() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_PADDING,
-                    KeyStoreKeyConstraints.Padding.toKeymaster(params.getPadding()));
-        }
-        if (params.getMaxUsesPerBoot() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_MAX_USES_PER_BOOT, params.getMaxUsesPerBoot());
+        for (int keymasterBlockMode :
+            KeyStoreKeyConstraints.BlockMode.allToKeymaster(params.getBlockModes())) {
+            args.addInt(KeymasterDefs.KM_TAG_BLOCK_MODE, keymasterBlockMode);
         }
-        if (params.getMinSecondsBetweenOperations() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_MIN_SECONDS_BETWEEN_OPS,
-                    params.getMinSecondsBetweenOperations());
+        for (int keymasterPadding :
+            KeyStoreKeyConstraints.Padding.allToKeymaster(params.getPaddings())) {
+            args.addInt(KeymasterDefs.KM_TAG_PADDING, keymasterPadding);
         }
-        if (params.getUserAuthenticators().isEmpty()) {
+        if (params.getUserAuthenticators() == 0) {
             args.addBoolean(KeymasterDefs.KM_TAG_NO_AUTH_REQUIRED);
         } else {
             args.addInt(KeymasterDefs.KM_TAG_USER_AUTH_TYPE,
                     KeyStoreKeyConstraints.UserAuthenticator.allToKeymaster(
                             params.getUserAuthenticators()));
         }
-        if (params.getUserAuthenticationValidityDurationSeconds() != null) {
+        if (params.getUserAuthenticationValidityDurationSeconds() != -1) {
             args.addInt(KeymasterDefs.KM_TAG_AUTH_TIMEOUT,
                     params.getUserAuthenticationValidityDurationSeconds());
         }
diff --git a/keystore/java/android/security/KeyGeneratorSpec.java b/keystore/java/android/security/KeyGeneratorSpec.java
index 1311368..3ada7f6 100644
--- a/keystore/java/android/security/KeyGeneratorSpec.java
+++ b/keystore/java/android/security/KeyGeneratorSpec.java
@@ -19,12 +19,8 @@ package android.security;
 import android.content.Context;
 import android.text.TextUtils;
 
-import java.security.cert.Certificate;
 import java.security.spec.AlgorithmParameterSpec;
-import java.util.Collections;
 import java.util.Date;
-import java.util.HashSet;
-import java.util.Set;
 
 import javax.crypto.KeyGenerator;
 import javax.crypto.SecretKey;
@@ -33,13 +29,13 @@ import javax.crypto.SecretKey;
  * {@link AlgorithmParameterSpec} for initializing a {@code KeyGenerator} that works with
  * <a href="{@docRoot}training/articles/keystore.html">Android KeyStore facility</a>.
  *
- * <p>The Android KeyStore facility is accessed through a {@link KeyGenerator} API
- * using the {@code AndroidKeyStore} provider. The {@code context} passed in may be used to pop up
- * some UI to ask the user to unlock or initialize the Android KeyStore facility.
+ * <p>The Android KeyStore facility is accessed through a {@link KeyGenerator} API using the
+ * {@code AndroidKeyStore} provider. The {@code context} passed in may be used to pop up some UI to
+ * ask the user to unlock or initialize the Android KeyStore facility.
  *
  * <p>After generation, the {@code keyStoreAlias} is used with the
  * {@link java.security.KeyStore#getEntry(String, java.security.KeyStore.ProtectionParameter)}
- * interface to retrieve the {@link SecretKey} and its associated {@link Certificate} chain.
+ * interface to retrieve the {@link SecretKey}.
  *
  * @hide
  */
@@ -52,13 +48,11 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
     private final Date mKeyValidityStart;
     private final Date mKeyValidityForOriginationEnd;
     private final Date mKeyValidityForConsumptionEnd;
-    private final @KeyStoreKeyConstraints.PurposeEnum Integer mPurposes;
-    private final @KeyStoreKeyConstraints.PaddingEnum Integer mPadding;
-    private final @KeyStoreKeyConstraints.BlockModeEnum Integer mBlockMode;
-    private final Integer mMinSecondsBetweenOperations;
-    private final Integer mMaxUsesPerBoot;
-    private final Set<Integer> mUserAuthenticators;
-    private final Integer mUserAuthenticationValidityDurationSeconds;
+    private final @KeyStoreKeyConstraints.PurposeEnum int mPurposes;
+    private final @KeyStoreKeyConstraints.PaddingEnum int mPaddings;
+    private final @KeyStoreKeyConstraints.BlockModeEnum int mBlockModes;
+    private final @KeyStoreKeyConstraints.UserAuthenticatorEnum int mUserAuthenticators;
+    private final int mUserAuthenticationValidityDurationSeconds;
 
     private KeyGeneratorSpec(
             Context context,
@@ -68,19 +62,17 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
             Date keyValidityStart,
             Date keyValidityForOriginationEnd,
             Date keyValidityForConsumptionEnd,
-            @KeyStoreKeyConstraints.PurposeEnum Integer purposes,
-            @KeyStoreKeyConstraints.PaddingEnum Integer padding,
-            @KeyStoreKeyConstraints.BlockModeEnum Integer blockMode,
-            Integer minSecondsBetweenOperations,
-            Integer maxUsesPerBoot,
-            Set<Integer> userAuthenticators,
-            Integer userAuthenticationValidityDurationSeconds) {
+            @KeyStoreKeyConstraints.PurposeEnum int purposes,
+            @KeyStoreKeyConstraints.PaddingEnum int paddings,
+            @KeyStoreKeyConstraints.BlockModeEnum int blockModes,
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators,
+            int userAuthenticationValidityDurationSeconds) {
         if (context == null) {
             throw new IllegalArgumentException("context == null");
         } else if (TextUtils.isEmpty(keyStoreAlias)) {
             throw new IllegalArgumentException("keyStoreAlias must not be empty");
-        } else if ((userAuthenticationValidityDurationSeconds != null)
-                && (userAuthenticationValidityDurationSeconds < 0)) {
+        } else if ((userAuthenticationValidityDurationSeconds < 0)
+                && (userAuthenticationValidityDurationSeconds != -1)) {
             throw new IllegalArgumentException(
                     "userAuthenticationValidityDurationSeconds must not be negative");
         }
@@ -93,13 +85,9 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
         mKeyValidityForOriginationEnd = keyValidityForOriginationEnd;
         mKeyValidityForConsumptionEnd = keyValidityForConsumptionEnd;
         mPurposes = purposes;
-        mPadding = padding;
-        mBlockMode = blockMode;
-        mMinSecondsBetweenOperations = minSecondsBetweenOperations;
-        mMaxUsesPerBoot = maxUsesPerBoot;
-        mUserAuthenticators = (userAuthenticators != null)
-                ? new HashSet<Integer>(userAuthenticators)
-                : Collections.<Integer>emptySet();
+        mPaddings = paddings;
+        mBlockModes = blockModes;
+        mUserAuthenticators = userAuthenticators;
         mUserAuthenticationValidityDurationSeconds = userAuthenticationValidityDurationSeconds;
     }
 
@@ -145,8 +133,6 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
      * Gets the time instant after which the key is no longer valid for decryption and verification.
      *
      * @return instant or {@code null} if not restricted.
-     *
-     * @hide
      */
     public Date getKeyValidityForConsumptionEnd() {
         return mKeyValidityForConsumptionEnd;
@@ -163,78 +149,43 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
 
     /**
      * Gets the set of purposes for which the key can be used.
-     *
-     * @return set of purposes or {@code null} if the key can be used for any purpose.
      */
-    public @KeyStoreKeyConstraints.PurposeEnum Integer getPurposes() {
+    public @KeyStoreKeyConstraints.PurposeEnum int getPurposes() {
         return mPurposes;
     }
 
     /**
-     * Gets the padding scheme to which the key is restricted.
-     *
-     * @return padding scheme or {@code null} if the padding scheme is not restricted.
-     */
-    public @KeyStoreKeyConstraints.PaddingEnum Integer getPadding() {
-        return mPadding;
-    }
-
-    /**
-     * Gets the block mode to which the key is restricted when used for encryption or decryption.
-     *
-     * @return block more or {@code null} if block mode is not restricted.
-     *
-     * @hide
-     */
-    public @KeyStoreKeyConstraints.BlockModeEnum Integer getBlockMode() {
-        return mBlockMode;
-    }
-
-    /**
-     * Gets the minimum number of seconds that must expire since the most recent use of the key
-     * before it can be used again.
-     *
-     * @return number of seconds or {@code null} if there is no restriction on how frequently a key
-     *         can be used.
-     *
-     * @hide
+     * Gets the set of padding schemes to which the key is restricted.
      */
-    public Integer getMinSecondsBetweenOperations() {
-        return mMinSecondsBetweenOperations;
+    public @KeyStoreKeyConstraints.PaddingEnum int getPaddings() {
+        return mPaddings;
     }
 
     /**
-     * Gets the number of times the key can be used without rebooting the device.
-     *
-     * @return maximum number of times or {@code null} if there is no restriction.
-     * @hide
+     * Gets the set of block modes to which the key is restricted.
      */
-    public Integer getMaxUsesPerBoot() {
-        return mMaxUsesPerBoot;
+    public @KeyStoreKeyConstraints.BlockModeEnum int getBlockModes() {
+        return mBlockModes;
     }
 
     /**
-     * Gets the user authenticators which protect access to this key. The key can only be used iff
-     * the user has authenticated to at least one of these user authenticators.
-     *
-     * @return user authenticators or empty set if the key can be used without user authentication.
+     * Gets the set of user authenticators which protect access to this key. The key can only be
+     * used iff the user has authenticated to at least one of these user authenticators.
      *
-     * @hide
+     * @return user authenticators or {@code 0} if the key can be used without user authentication.
      */
-    public Set<Integer> getUserAuthenticators() {
-        return new HashSet<Integer>(mUserAuthenticators);
+    public @KeyStoreKeyConstraints.UserAuthenticatorEnum int getUserAuthenticators() {
+        return mUserAuthenticators;
     }
 
     /**
      * Gets the duration of time (seconds) for which this key can be used after the user
      * successfully authenticates to one of the associated user authenticators.
      *
-     * @return duration in seconds or {@code null} if not restricted. {@code 0} means authentication
+     * @return duration in seconds or {@code -1} if not restricted. {@code 0} means authentication
      *         is required for every use of the key.
-     *
-     * @hide
      */
-    public Integer getUserAuthenticationValidityDurationSeconds() {
+    public int getUserAuthenticationValidityDurationSeconds() {
         return mUserAuthenticationValidityDurationSeconds;
     }
 
@@ -253,13 +204,11 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
         private Date mKeyValidityStart;
         private Date mKeyValidityForOriginationEnd;
         private Date mKeyValidityForConsumptionEnd;
-        private @KeyStoreKeyConstraints.PurposeEnum Integer mPurposes;
-        private @KeyStoreKeyConstraints.PaddingEnum Integer mPadding;
-        private @KeyStoreKeyConstraints.BlockModeEnum Integer mBlockMode;
-        private Integer mMinSecondsBetweenOperations;
-        private Integer mMaxUsesPerBoot;
-        private Set<Integer> mUserAuthenticators;
-        private Integer mUserAuthenticationValidityDurationSeconds;
+        private @KeyStoreKeyConstraints.PurposeEnum int mPurposes;
+        private @KeyStoreKeyConstraints.PaddingEnum int mPaddings;
+        private @KeyStoreKeyConstraints.BlockModeEnum int mBlockModes;
+        private @KeyStoreKeyConstraints.UserAuthenticatorEnum int mUserAuthenticators;
+        private int mUserAuthenticationValidityDurationSeconds = -1;
 
         /**
          * Creates a new instance of the {@code Builder} with the given {@code context}. The
@@ -318,8 +267,6 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
          * <b>By default, the key is valid at any instant.
          *
          * @see #setKeyValidityEnd(Date)
-         *
-         * @hide
          */
         public Builder setKeyValidityStart(Date startDate) {
             mKeyValidityStart = startDate;
@@ -334,8 +281,6 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
          * @see #setKeyValidityStart(Date)
          * @see #setKeyValidityForConsumptionEnd(Date)
          * @see #setKeyValidityForOriginationEnd(Date)
-         *
-         * @hide
          */
         public Builder setKeyValidityEnd(Date endDate) {
             setKeyValidityForOriginationEnd(endDate);
@@ -349,8 +294,6 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
          * <b>By default, the key is valid at any instant.
          *
          * @see #setKeyValidityForConsumptionEnd(Date)
-         *
-         * @hide
          */
         public Builder setKeyValidityForOriginationEnd(Date endDate) {
             mKeyValidityForOriginationEnd = endDate;
@@ -364,8 +307,6 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
          * <b>By default, the key is valid at any instant.
          *
          * @see #setKeyValidityForOriginationEnd(Date)
-         *
-         * @hide
          */
         public Builder setKeyValidityForConsumptionEnd(Date endDate) {
             mKeyValidityForConsumptionEnd = endDate;
@@ -373,11 +314,9 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
         }
 
         /**
-         * Restricts the purposes for which the key can be used to the provided set of purposes.
-         *
-         * <p>By default, the key can be used for encryption, decryption, signing, and verification.
+         * Restricts the key to being used only for the provided set of purposes.
          *
-         * @hide
+         * <p>This restriction must be specified. There is no default.
          */
         public Builder setPurposes(@KeyStoreKeyConstraints.PurposeEnum int purposes) {
             mPurposes = purposes;
@@ -385,53 +324,24 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
         }
 
         /**
-         * Restricts the key to being used only with the provided padding scheme. Attempts to use
+         * Restricts the key to being used only with the provided padding schemes. Attempts to use
          * the key with any other padding will be rejected.
          *
          * <p>This restriction must be specified for keys which are used for encryption/decryption.
-         *
-         * @hide
          */
-        public Builder setPadding(@KeyStoreKeyConstraints.PaddingEnum int padding) {
-            mPadding = padding;
+        public Builder setPaddings(@KeyStoreKeyConstraints.PaddingEnum int paddings) {
+            mPaddings = paddings;
             return this;
         }
 
         /**
-         * Restricts the key to being used only with the provided block mode when encrypting or
-         * decrypting. Attempts to use the key with any other block modes will be rejected.
+         * Restricts the key to being used only with the provided block modes. Attempts to use the
+         * key with any other block modes will be rejected.
          *
          * <p>This restriction must be specified for keys which are used for encryption/decryption.
-         *
-         * @hide
          */
-        public Builder setBlockMode(@KeyStoreKeyConstraints.BlockModeEnum int blockMode) {
-            mBlockMode = blockMode;
-            return this;
-        }
-
-        /**
-         * Sets the minimum number of seconds that must expire since the most recent use of the key
-         * before it can be used again.
-         *
-         * <p>By default, there is no restriction on how frequently a key can be used.
-         *
-         * @hide
-         */
-        public Builder setMinSecondsBetweenOperations(int seconds) {
-            mMinSecondsBetweenOperations = seconds;
-            return this;
-        }
-
-        /**
-         * Sets the maximum number of times a key can be used without rebooting the device.
-         *
-         * <p>By default, the key can be used for an unlimited number of times.
-         *
-         * @hide
-         */
-        public Builder setMaxUsesPerBoot(int count) {
-            mMaxUsesPerBoot = count;
+        public Builder setBlockModes(@KeyStoreKeyConstraints.BlockModeEnum int blockModes) {
+            mBlockModes = blockModes;
             return this;
         }
 
@@ -445,12 +355,10 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
          *        without user authentication.
          *
          * @see #setUserAuthenticationValidityDurationSeconds(int)
-         *
-         * @hide
          */
-        public Builder setUserAuthenticators(Set<Integer> userAuthenticators) {
-            mUserAuthenticators =
-                    (userAuthenticators != null) ? new HashSet<Integer>(userAuthenticators) : null;
+        public Builder setUserAuthenticators(
+                @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators) {
+            mUserAuthenticators = userAuthenticators;
             return this;
         }
 
@@ -463,9 +371,7 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
          * @param seconds duration in seconds or {@code 0} if the user needs to authenticate for
          *        every use of the key.
          *
-         * @see #setUserAuthenticators(Set)
-         *
-         * @hide
+         * @see #setUserAuthenticators(int)
          */
         public Builder setUserAuthenticationValidityDurationSeconds(int seconds) {
             mUserAuthenticationValidityDurationSeconds = seconds;
@@ -478,10 +384,18 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
          * @throws IllegalArgumentException if a required field is missing or violates a constraint.
          */
         public KeyGeneratorSpec build() {
-            return new KeyGeneratorSpec(mContext, mKeystoreAlias, mFlags, mKeySize,
-                    mKeyValidityStart, mKeyValidityForOriginationEnd, mKeyValidityForConsumptionEnd,
-                    mPurposes, mPadding, mBlockMode, mMinSecondsBetweenOperations, mMaxUsesPerBoot,
-                    mUserAuthenticators, mUserAuthenticationValidityDurationSeconds);
+            return new KeyGeneratorSpec(mContext,
+                    mKeystoreAlias,
+                    mFlags,
+                    mKeySize,
+                    mKeyValidityStart,
+                    mKeyValidityForOriginationEnd,
+                    mKeyValidityForConsumptionEnd,
+                    mPurposes,
+                    mPaddings,
+                    mBlockModes,
+                    mUserAuthenticators,
+                    mUserAuthenticationValidityDurationSeconds);
         }
     }
 }
diff --git a/keystore/java/android/security/KeyPairGeneratorSpec.java b/keystore/java/android/security/KeyPairGeneratorSpec.java
index 0001604..edaa9a5 100644
--- a/keystore/java/android/security/KeyPairGeneratorSpec.java
+++ b/keystore/java/android/security/KeyPairGeneratorSpec.java
@@ -24,10 +24,7 @@ import java.security.NoSuchAlgorithmException;
 import java.security.PrivateKey;
 import java.security.cert.Certificate;
 import java.security.spec.AlgorithmParameterSpec;
-import java.util.Collections;
 import java.util.Date;
-import java.util.HashSet;
-import java.util.Set;
 
 import javax.security.auth.x500.X500Principal;
 
@@ -81,21 +78,17 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
 
     private final Date mKeyValidityForConsumptionEnd;
 
-    private final @KeyStoreKeyConstraints.PurposeEnum Integer mPurposes;
+    private final @KeyStoreKeyConstraints.PurposeEnum int mPurposes;
 
-    private final @KeyStoreKeyConstraints.DigestEnum Integer mDigest;
+    private final @KeyStoreKeyConstraints.DigestEnum int mDigests;
 
-    private final @KeyStoreKeyConstraints.PaddingEnum Integer mPadding;
+    private final @KeyStoreKeyConstraints.PaddingEnum int mPaddings;
 
-    private final @KeyStoreKeyConstraints.BlockModeEnum Integer mBlockMode;
+    private final @KeyStoreKeyConstraints.BlockModeEnum int mBlockModes;
 
-    private final Integer mMinSecondsBetweenOperations;
+    private final @KeyStoreKeyConstraints.UserAuthenticatorEnum int mUserAuthenticators;
 
-    private final Integer mMaxUsesPerBoot;
-
-    private final Set<Integer> mUserAuthenticators;
-
-    private final Integer mUserAuthenticationValidityDurationSeconds;
+    private final int mUserAuthenticationValidityDurationSeconds;
 
     /**
      * Parameter specification for the "{@code AndroidKeyPairGenerator}"
@@ -135,14 +128,12 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
             Date keyValidityStart,
             Date keyValidityForOriginationEnd,
             Date keyValidityForConsumptionEnd,
-            @KeyStoreKeyConstraints.PurposeEnum Integer purposes,
-            @KeyStoreKeyConstraints.DigestEnum Integer digest,
-            @KeyStoreKeyConstraints.PaddingEnum Integer padding,
-            @KeyStoreKeyConstraints.BlockModeEnum Integer blockMode,
-            Integer minSecondsBetweenOperations,
-            Integer maxUsesPerBoot,
-            Set<Integer> userAuthenticators,
-            Integer userAuthenticationValidityDurationSeconds) {
+            @KeyStoreKeyConstraints.PurposeEnum int purposes,
+            @KeyStoreKeyConstraints.DigestEnum int digests,
+            @KeyStoreKeyConstraints.PaddingEnum int paddings,
+            @KeyStoreKeyConstraints.BlockModeEnum int blockModes,
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators,
+            int userAuthenticationValidityDurationSeconds) {
         if (context == null) {
             throw new IllegalArgumentException("context == null");
         } else if (TextUtils.isEmpty(keyStoreAlias)) {
@@ -157,8 +148,8 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
             throw new IllegalArgumentException("endDate == null");
         } else if (endDate.before(startDate)) {
             throw new IllegalArgumentException("endDate < startDate");
-        } else if ((userAuthenticationValidityDurationSeconds != null)
-                && (userAuthenticationValidityDurationSeconds < 0)) {
+        } else if ((userAuthenticationValidityDurationSeconds < 0)
+                && (userAuthenticationValidityDurationSeconds != -1)) {
             throw new IllegalArgumentException(
                     "userAuthenticationValidityDurationSeconds must not be negative");
         }
@@ -177,14 +168,10 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
         mKeyValidityForOriginationEnd = keyValidityForOriginationEnd;
         mKeyValidityForConsumptionEnd = keyValidityForConsumptionEnd;
         mPurposes = purposes;
-        mDigest = digest;
-        mPadding = padding;
-        mBlockMode = blockMode;
-        mMinSecondsBetweenOperations = minSecondsBetweenOperations;
-        mMaxUsesPerBoot = maxUsesPerBoot;
-        mUserAuthenticators = (userAuthenticators != null)
-                ? new HashSet<Integer>(userAuthenticators)
-                : Collections.<Integer>emptySet();
+        mDigests = digests;
+        mPaddings = paddings;
+        mBlockModes = blockModes;
+        mUserAuthenticators = userAuthenticators;
         mUserAuthenticationValidityDurationSeconds = userAuthenticationValidityDurationSeconds;
     }
 
@@ -196,8 +183,7 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
             AlgorithmParameterSpec spec, X500Principal subjectDN, BigInteger serialNumber,
             Date startDate, Date endDate, int flags) {
         this(context, keyStoreAlias, keyType, keySize, spec, subjectDN, serialNumber, startDate,
-                endDate, flags, startDate, endDate, endDate, null, null, null, null, null, null,
-                null, null);
+                endDate, flags, startDate, endDate, endDate, 0, 0, 0, 0, 0, -1);
     }
 
     /**
@@ -323,90 +309,52 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
     /**
      * Gets the set of purposes for which the key can be used.
      *
-     * @return set of purposes or {@code null} if the key can be used for any purpose.
-     *
      * @hide
      */
-    public @KeyStoreKeyConstraints.PurposeEnum Integer getPurposes() {
+    public @KeyStoreKeyConstraints.PurposeEnum int getPurposes() {
         return mPurposes;
     }
 
     /**
-     * Gets the digest to which the key is restricted.
-     *
-     * @return digest or {@code null} if the digest is not restricted.
+     * Gets the set of digests to which the key is restricted.
      *
      * @hide
      */
-    public @KeyStoreKeyConstraints.DigestEnum Integer getDigest() {
-        return mDigest;
+    public @KeyStoreKeyConstraints.DigestEnum int getDigests() {
+        return mDigests;
     }
 
     /**
-     * Gets the padding scheme to which the key is restricted.
-     *
-     * @return padding scheme or {@code null} if the padding scheme is not restricted.
+     * Gets the set of padding schemes to which the key is restricted.
      *
      * @hide
      */
-    public @KeyStoreKeyConstraints.PaddingEnum Integer getPadding() {
-        return mPadding;
+    public @KeyStoreKeyConstraints.PaddingEnum int getPaddings() {
+        return mPaddings;
     }
 
     /**
-     * Gets the block mode to which the key is restricted when used for encryption or decryption.
-     *
-     * @return block more or {@code null} if block mode is not restricted.
-     *
-     * @hide
-     */
-    public @KeyStoreKeyConstraints.BlockModeEnum Integer getBlockMode() {
-        return mBlockMode;
-    }
-
-    /**
-     * Gets the minimum number of seconds that must expire since the most recent use of the private
-     * key before it can be used again.
-     *
-     * <p>This restriction applies only to private key operations. Public key operations are not
-     * restricted.
-     *
-     * @return number of seconds or {@code null} if there is no restriction on how frequently a key
-     *         can be used.
-     *
-     * @hide
-     */
-    public Integer getMinSecondsBetweenOperations() {
-        return mMinSecondsBetweenOperations;
-    }
-
-    /**
-     * Gets the number of times the private key can be used without rebooting the device.
-     *
-     * <p>This restriction applies only to private key operations. Public key operations are not
-     * restricted.
-     *
-     * @return maximum number of times or {@code null} if there is no restriction.
+     * Gets the set of block modes to which the key is restricted.
      *
      * @hide
      */
-    public Integer getMaxUsesPerBoot() {
-        return mMaxUsesPerBoot;
+    public @KeyStoreKeyConstraints.BlockModeEnum int getBlockModes() {
+        return mBlockModes;
     }
 
     /**
-     * Gets the user authenticators which protect access to the private key. The key can only be
-     * used iff the user has authenticated to at least one of these user authenticators.
+     * Gets the set of user authenticators which protect access to the private key. The key can only
+     * be used iff the user has authenticated to at least one of these user authenticators.
      *
      * <p>This restriction applies only to private key operations. Public key operations are not
      * restricted.
      *
-     * @return user authenticators or empty set if the key can be used without user authentication.
+     * @return user authenticators or {@code 0} if the key can be used without user authentication.
      *
      * @hide
      */
-    public Set<Integer> getUserAuthenticators() {
-        return new HashSet<Integer>(mUserAuthenticators);
+    public @KeyStoreKeyConstraints.UserAuthenticatorEnum int getUserAuthenticators() {
+        return mUserAuthenticators;
     }
 
     /**
@@ -416,12 +364,12 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
      * <p>This restriction applies only to private key operations. Public key operations are not
      * restricted.
      *
-     * @return duration in seconds or {@code null} if not restricted. {@code 0} means authentication
+     * @return duration in seconds or {@code -1} if not restricted. {@code 0} means authentication
      *         is required for every use of the key.
      *
      * @hide
      */
-    public Integer getUserAuthenticationValidityDurationSeconds() {
+    public int getUserAuthenticationValidityDurationSeconds() {
         return mUserAuthenticationValidityDurationSeconds;
     }
 
@@ -473,21 +421,17 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
 
         private Date mKeyValidityForConsumptionEnd;
 
-        private @KeyStoreKeyConstraints.PurposeEnum Integer mPurposes;
-
-        private @KeyStoreKeyConstraints.DigestEnum Integer mDigest;
+        private @KeyStoreKeyConstraints.PurposeEnum int mPurposes;
 
-        private @KeyStoreKeyConstraints.PaddingEnum Integer mPadding;
+        private @KeyStoreKeyConstraints.DigestEnum int mDigests;
 
-        private @KeyStoreKeyConstraints.BlockModeEnum Integer mBlockMode;
+        private @KeyStoreKeyConstraints.PaddingEnum int mPaddings;
 
-        private Integer mMinSecondsBetweenOperations;
+        private @KeyStoreKeyConstraints.BlockModeEnum int mBlockModes;
 
-        private Integer mMaxUsesPerBoot;
+        private @KeyStoreKeyConstraints.UserAuthenticatorEnum int mUserAuthenticators;
 
-        private Set<Integer> mUserAuthenticators;
-
-        private Integer mUserAuthenticationValidityDurationSeconds;
+        private int mUserAuthenticationValidityDurationSeconds = -1;
 
         /**
          * Creates a new instance of the {@code Builder} with the given
@@ -675,9 +619,9 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
         }
 
         /**
-         * Restricts the purposes for which the key can be used to the provided set of purposes.
+         * Restricts the key to being used only for the provided set of purposes.
          *
-         * <p>By default, the key can be used for encryption, decryption, signing, and verification.
+         * <p>This restriction must be specified. There is no default.
          *
          * @hide
          */
@@ -687,28 +631,28 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
         }
 
         /**
-         * Restricts the key to being used only with the provided digest. Attempts to use the key
+         * Restricts the key to being used only with the provided digests. Attempts to use the key
          * with any other digests be rejected.
          *
          * <p>This restriction must be specified for keys which are used for signing/verification.
          *
          * @hide
          */
-        public Builder setDigest(@KeyStoreKeyConstraints.DigestEnum int digest) {
-            mDigest = digest;
+        public Builder setDigests(@KeyStoreKeyConstraints.DigestEnum int digests) {
+            mDigests = digests;
             return this;
         }
 
         /**
-         * Restricts the key to being used only with the provided padding scheme. Attempts to use
+         * Restricts the key to being used only with the provided padding schemes. Attempts to use
          * the key with any other padding will be rejected.
          *
          * <p>This restriction must be specified for keys which are used for encryption/decryption.
          *
          * @hide
          */
-        public Builder setPadding(@KeyStoreKeyConstraints.PaddingEnum int padding) {
-            mPadding = padding;
+        public Builder setPaddings(@KeyStoreKeyConstraints.PaddingEnum int paddings) {
+            mPaddings = paddings;
             return this;
         }
 
@@ -720,39 +664,8 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
          *
          * @hide
          */
-        public Builder setBlockMode(@KeyStoreKeyConstraints.BlockModeEnum int blockMode) {
-            mBlockMode = blockMode;
-            return this;
-        }
-
-        /**
-         * Sets the minimum number of seconds that must expire since the most recent use of the key
-         * before it can be used again.
-         *
-         * <p>By default, there is no restriction on how frequently a key can be used.
-         *
-         * <p>This restriction applies only to private key operations. Public key operations are not
-         * restricted.
-         *
-         * @hide
-         */
-        public Builder setMinSecondsBetweenOperations(int seconds) {
-            mMinSecondsBetweenOperations = seconds;
-            return this;
-        }
-
-        /**
-         * Sets the maximum number of times a key can be used without rebooting the device.
-         *
-         * <p>By default, the key can be used for an unlimited number of times.
-         *
-         * <p>This restriction applies only to private key operations. Public key operations are not
-         * restricted.
-         *
-         * @hide
-         */
-        public Builder setMaxUsesPerBoot(int count) {
-            mMaxUsesPerBoot = count;
+        public Builder setBlockModes(@KeyStoreKeyConstraints.BlockModeEnum int blockModes) {
+            mBlockModes = blockModes;
             return this;
         }
 
@@ -765,16 +678,16 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
          * <p>This restriction applies only to private key operations. Public key operations are not
          * restricted.
          *
-         * @param userAuthenticators user authenticators or empty list if this key can be accessed
+         * @param userAuthenticators user authenticators or {@code 0} if this key can be accessed
          *        without user authentication.
          *
          * @see #setUserAuthenticationValidityDurationSeconds(int)
          *
          * @hide
          */
-        public Builder setUserAuthenticators(Set<Integer> userAuthenticators) {
-            mUserAuthenticators =
-                    (userAuthenticators != null) ? new HashSet<Integer>(userAuthenticators) : null;
+        public Builder setUserAuthenticators(
+                @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators) {
+            mUserAuthenticators = userAuthenticators;
             return this;
         }
 
@@ -790,7 +703,7 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
          * @param seconds duration in seconds or {@code 0} if the user needs to authenticate for
          *        every use of the key.
          *
-         * @see #setUserAuthenticators(Set)
+         * @see #setUserAuthenticators(int)
          *
          * @hide
          */
@@ -820,11 +733,9 @@ public final class KeyPairGeneratorSpec implements AlgorithmParameterSpec {
                     mKeyValidityForOriginationEnd,
                     mKeyValidityForConsumptionEnd,
                     mPurposes,
-                    mDigest,
-                    mPadding,
-                    mBlockMode,
-                    mMinSecondsBetweenOperations,
-                    mMaxUsesPerBoot,
+                    mDigests,
+                    mPaddings,
+                    mBlockModes,
                     mUserAuthenticators,
                     mUserAuthenticationValidityDurationSeconds);
         }
diff --git a/keystore/java/android/security/KeyStoreKeyConstraints.java b/keystore/java/android/security/KeyStoreKeyConstraints.java
index c27ccb1..bd7aacf 100644
--- a/keystore/java/android/security/KeyStoreKeyConstraints.java
+++ b/keystore/java/android/security/KeyStoreKeyConstraints.java
@@ -21,12 +21,8 @@ import android.security.keymaster.KeymasterDefs;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
-import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
-import java.util.HashSet;
 import java.util.Locale;
-import java.util.Set;
 
 /**
  * Constraints for {@code AndroidKeyStore} keys.
@@ -37,7 +33,8 @@ public abstract class KeyStoreKeyConstraints {
     private KeyStoreKeyConstraints() {}
 
     @Retention(RetentionPolicy.SOURCE)
-    @IntDef(flag=true, value={Purpose.ENCRYPT, Purpose.DECRYPT, Purpose.SIGN, Purpose.VERIFY})
+    @IntDef(flag = true,
+            value = {Purpose.ENCRYPT, Purpose.DECRYPT, Purpose.SIGN, Purpose.VERIFY})
     public @interface PurposeEnum {}
 
     /**
@@ -67,11 +64,6 @@ public abstract class KeyStoreKeyConstraints {
         public static final int VERIFY = 1 << 3;
 
         /**
-         * Number of flags defined above. Needs to be kept in sync with the flags above.
-         */
-        private static final int VALUE_COUNT = 4;
-
-        /**
          * @hide
          */
         public static int toKeymaster(@PurposeEnum int purpose) {
@@ -110,22 +102,12 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * @hide
          */
-        public static int[] allToKeymaster(int purposes) {
-            int[] result = new int[VALUE_COUNT];
-            int resultCount = 0;
-            int purpose = 1;
-            for (int i = 0; i < 32; i++) {
-                if ((purposes & 1) != 0) {
-                    result[resultCount] = toKeymaster(purpose);
-                    resultCount++;
-                }
-                purposes >>>= 1;
-                purpose <<= 1;
-                if (purposes == 0) {
-                    break;
-                }
+        public static int[] allToKeymaster(@PurposeEnum int purposes) {
+            int[] result = getSetFlags(purposes);
+            for (int i = 0; i < result.length; i++) {
+                result[i] = toKeymaster(result[i]);
             }
-            return Arrays.copyOf(result, resultCount);
+            return result;
         }
 
         /**
@@ -244,7 +226,8 @@ public abstract class KeyStoreKeyConstraints {
     }
 
     @Retention(RetentionPolicy.SOURCE)
-    @IntDef({Padding.NONE, Padding.ZERO, Padding.PKCS7})
+    @IntDef(flag = true,
+            value = {Padding.NONE, Padding.PKCS7})
     public @interface PaddingEnum {}
 
     /**
@@ -256,17 +239,12 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * No padding.
          */
-        public static final int NONE = 0;
-
-        /**
-         * Pad with zeros.
-         */
-        public static final int ZERO = 1;
+        public static final int NONE = 1 << 0;
 
         /**
          * PKCS#7 padding.
          */
-        public static final int PKCS7 = 2;
+        public static final int PKCS7 = 1 << 1;
 
         /**
          * @hide
@@ -275,8 +253,6 @@ public abstract class KeyStoreKeyConstraints {
             switch (padding) {
                 case NONE:
                     return KeymasterDefs.KM_PAD_NONE;
-                case ZERO:
-                    return KeymasterDefs.KM_PAD_ZERO;
                 case PKCS7:
                     return KeymasterDefs.KM_PAD_PKCS7;
                 default:
@@ -291,8 +267,6 @@ public abstract class KeyStoreKeyConstraints {
             switch (padding) {
                 case KeymasterDefs.KM_PAD_NONE:
                     return NONE;
-                case KeymasterDefs.KM_PAD_ZERO:
-                    return ZERO;
                 case KeymasterDefs.KM_PAD_PKCS7:
                     return PKCS7;
                 default:
@@ -307,8 +281,6 @@ public abstract class KeyStoreKeyConstraints {
             switch (padding) {
                 case NONE:
                     return "NONE";
-                case ZERO:
-                    return "ZERO";
                 case PKCS7:
                     return "PKCS#7";
                 default:
@@ -329,10 +301,33 @@ public abstract class KeyStoreKeyConstraints {
                 throw new IllegalArgumentException("Unknown padding: " + padding);
             }
         }
+
+        /**
+         * @hide
+         */
+        public static int[] allToKeymaster(@PaddingEnum int paddings) {
+            int[] result = getSetFlags(paddings);
+            for (int i = 0; i < result.length; i++) {
+                result[i] = toKeymaster(result[i]);
+            }
+            return result;
+        }
+
+        /**
+         * @hide
+         */
+        public static @PaddingEnum int allFromKeymaster(Collection<Integer> paddings) {
+            @PaddingEnum int result = 0;
+            for (int keymasterPadding : paddings) {
+                result |= fromKeymaster(keymasterPadding);
+            }
+            return result;
+        }
     }
 
     @Retention(RetentionPolicy.SOURCE)
-    @IntDef({Digest.NONE, Digest.SHA256})
+    @IntDef(flag = true,
+            value = {Digest.NONE, Digest.SHA256})
     public @interface DigestEnum {}
 
     /**
@@ -345,12 +340,12 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * No digest: sign/authenticate the raw message.
          */
-        public static final int NONE = 0;
+        public static final int NONE = 1 << 0;
 
         /**
          * SHA-256 digest.
          */
-        public static final int SHA256 = 1;
+        public static final int SHA256 = 1 << 1;
 
         /**
          * @hide
@@ -369,6 +364,18 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * @hide
          */
+        public static String[] allToString(@DigestEnum int digests) {
+            int[] values = getSetFlags(digests);
+            String[] result = new String[values.length];
+            for (int i = 0; i < values.length; i++) {
+                result[i] = toString(values[i]);
+            }
+            return result;
+        }
+
+        /**
+         * @hide
+         */
         public static int toKeymaster(@DigestEnum int digest) {
             switch (digest) {
                 case NONE:
@@ -397,6 +404,28 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * @hide
          */
+        public static int[] allToKeymaster(@DigestEnum int digests) {
+            int[] result = getSetFlags(digests);
+            for (int i = 0; i < result.length; i++) {
+                result[i] = toKeymaster(result[i]);
+            }
+            return result;
+        }
+
+        /**
+         * @hide
+         */
+        public static @DigestEnum int allFromKeymaster(Collection<Integer> digests) {
+            @DigestEnum int result = 0;
+            for (int keymasterDigest : digests) {
+                result |= fromKeymaster(keymasterDigest);
+            }
+            return result;
+        }
+
+        /**
+         * @hide
+         */
         public static @DigestEnum Integer fromJCASecretKeyAlgorithm(String algorithm) {
             String algorithmLower = algorithm.toLowerCase(Locale.US);
             if (algorithmLower.startsWith("hmac")) {
@@ -441,7 +470,8 @@ public abstract class KeyStoreKeyConstraints {
     }
 
     @Retention(RetentionPolicy.SOURCE)
-    @IntDef({BlockMode.ECB, BlockMode.CBC, BlockMode.CTR})
+    @IntDef(flag = true,
+            value = {BlockMode.ECB, BlockMode.CBC, BlockMode.CTR})
     public @interface BlockModeEnum {}
 
     /**
@@ -451,13 +481,13 @@ public abstract class KeyStoreKeyConstraints {
         private BlockMode() {}
 
         /** Electronic Codebook (ECB) block mode. */
-        public static final int ECB = 0;
+        public static final int ECB = 1 << 0;
 
         /** Cipher Block Chaining (CBC) block mode. */
-        public static final int CBC = 1;
+        public static final int CBC = 1 << 1;
 
         /** Counter (CTR) block mode. */
-        public static final int CTR = 2;
+        public static final int CTR = 1 << 2;
 
         /**
          * @hide
@@ -494,6 +524,28 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * @hide
          */
+        public static int[] allToKeymaster(@BlockModeEnum int modes) {
+            int[] result = getSetFlags(modes);
+            for (int i = 0; i < result.length; i++) {
+                result[i] = toKeymaster(result[i]);
+            }
+            return result;
+        }
+
+        /**
+         * @hide
+         */
+        public static @BlockModeEnum int allFromKeymaster(Collection<Integer> modes) {
+            @BlockModeEnum int result = 0;
+            for (int keymasterMode : modes) {
+                result |= fromKeymaster(keymasterMode);
+            }
+            return result;
+        }
+
+        /**
+         * @hide
+         */
         public static String toString(@BlockModeEnum int mode) {
             switch (mode) {
                 case ECB:
@@ -525,7 +577,8 @@ public abstract class KeyStoreKeyConstraints {
     }
 
     @Retention(RetentionPolicy.SOURCE)
-    @IntDef({UserAuthenticator.LOCK_SCREEN})
+    @IntDef(flag = true,
+            value = {UserAuthenticator.LOCK_SCREEN})
     public @interface UserAuthenticatorEnum {}
 
     /**
@@ -535,7 +588,7 @@ public abstract class KeyStoreKeyConstraints {
         private UserAuthenticator() {}
 
         /** Lock screen. */
-        public static final int LOCK_SCREEN = 1;
+        public static final int LOCK_SCREEN = 1 << 0;
 
         /**
          * @hide
@@ -543,7 +596,7 @@ public abstract class KeyStoreKeyConstraints {
         public static int toKeymaster(@UserAuthenticatorEnum int userAuthenticator) {
             switch (userAuthenticator) {
                 case LOCK_SCREEN:
-                    return LOCK_SCREEN;
+                    return KeymasterDefs.HW_AUTH_PASSWORD;
                 default:
                     throw new IllegalArgumentException(
                             "Unknown user authenticator: " + userAuthenticator);
@@ -555,7 +608,7 @@ public abstract class KeyStoreKeyConstraints {
          */
         public static @UserAuthenticatorEnum int fromKeymaster(int userAuthenticator) {
             switch (userAuthenticator) {
-                case LOCK_SCREEN:
+                case KeymasterDefs.HW_AUTH_PASSWORD:
                     return LOCK_SCREEN;
                 default:
                     throw new IllegalArgumentException(
@@ -566,10 +619,15 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * @hide
          */
-        public static int allToKeymaster(Set<Integer> userAuthenticators) {
+        public static int allToKeymaster(@UserAuthenticatorEnum int userAuthenticators) {
             int result = 0;
-            for (@UserAuthenticatorEnum int userAuthenticator : userAuthenticators) {
-                result |= toKeymaster(userAuthenticator);
+            int userAuthenticator = 1;
+            while (userAuthenticators != 0) {
+                if ((userAuthenticators & 1) != 0) {
+                    result |= toKeymaster(userAuthenticator);
+                }
+                userAuthenticators >>>= 1;
+                userAuthenticator <<= 1;
             }
             return result;
         }
@@ -577,20 +635,17 @@ public abstract class KeyStoreKeyConstraints {
         /**
          * @hide
          */
-        public static Set<Integer> allFromKeymaster(int userAuthenticators) {
+        public static @UserAuthenticatorEnum int allFromKeymaster(int userAuthenticators) {
+            @UserAuthenticatorEnum int result = 0;
             int userAuthenticator = 1;
-            Set<Integer> result = null;
             while (userAuthenticators != 0) {
                 if ((userAuthenticators & 1) != 0) {
-                    if (result == null) {
-                        result = new HashSet<Integer>();
-                    }
-                    result.add(fromKeymaster(userAuthenticator));
+                    result |= fromKeymaster(userAuthenticator);
                 }
                 userAuthenticators >>>= 1;
                 userAuthenticator <<= 1;
             }
-            return (result != null) ? result : Collections.<Integer>emptySet();
+            return result;
         }
 
         /**
@@ -606,4 +661,38 @@ public abstract class KeyStoreKeyConstraints {
             }
         }
     }
+
+    private static final int[] EMPTY_INT_ARRAY = new int[0];
+
+    private static int[] getSetFlags(int flags) {
+        if (flags == 0) {
+            return EMPTY_INT_ARRAY;
+        }
+        int result[] = new int[getSetBitCount(flags)];
+        int resultOffset = 0;
+        int flag = 1;
+        while (flags != 0) {
+            if ((flags & 1) != 0) {
+                result[resultOffset] = flag;
+                resultOffset++;
+            }
+            flags >>>= 1;
+            flag <<= 1;
+        }
+        return result;
+    }
+
+    private static int getSetBitCount(int value) {
+        if (value == 0) {
+            return 0;
+        }
+        int result = 0;
+        while (value != 0) {
+            if ((value & 1) != 0) {
+                result++;
+            }
+            value >>>= 1;
+        }
+        return result;
+    }
 }
diff --git a/keystore/java/android/security/KeyStoreKeyGeneratorSpi.java b/keystore/java/android/security/KeyStoreKeyGeneratorSpi.java
index c9c9bd8..09499d0 100644
--- a/keystore/java/android/security/KeyStoreKeyGeneratorSpi.java
+++ b/keystore/java/android/security/KeyStoreKeyGeneratorSpi.java
@@ -109,39 +109,27 @@ public abstract class KeyStoreKeyGeneratorSpi extends KeyGeneratorSpi {
         }
         int keySizeBits = (spec.getKeySize() != null) ? spec.getKeySize() : mDefaultKeySizeBits;
         args.addInt(KeymasterDefs.KM_TAG_KEY_SIZE, keySizeBits);
-        @KeyStoreKeyConstraints.PurposeEnum int purposes = (spec.getPurposes() != null)
-                ? spec.getPurposes()
-                : (KeyStoreKeyConstraints.Purpose.ENCRYPT
-                        | KeyStoreKeyConstraints.Purpose.DECRYPT
-                        | KeyStoreKeyConstraints.Purpose.SIGN
-                        | KeyStoreKeyConstraints.Purpose.VERIFY);
+        int purposes = spec.getPurposes();
         for (int keymasterPurpose :
             KeyStoreKeyConstraints.Purpose.allToKeymaster(purposes)) {
             args.addInt(KeymasterDefs.KM_TAG_PURPOSE, keymasterPurpose);
         }
-        if (spec.getBlockMode() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_BLOCK_MODE,
-                    KeyStoreKeyConstraints.BlockMode.toKeymaster(spec.getBlockMode()));
+        for (int keymasterBlockMode :
+            KeyStoreKeyConstraints.BlockMode.allToKeymaster(spec.getBlockModes())) {
+            args.addInt(KeymasterDefs.KM_TAG_BLOCK_MODE, keymasterBlockMode);
         }
-        if (spec.getPadding() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_PADDING,
-                    KeyStoreKeyConstraints.Padding.toKeymaster(spec.getPadding()));
+        for (int keymasterPadding :
+            KeyStoreKeyConstraints.Padding.allToKeymaster(spec.getPaddings())) {
+            args.addInt(KeymasterDefs.KM_TAG_PADDING, keymasterPadding);
         }
-        if (spec.getMaxUsesPerBoot() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_MAX_USES_PER_BOOT, spec.getMaxUsesPerBoot());
-        }
-        if (spec.getMinSecondsBetweenOperations() != null) {
-            args.addInt(KeymasterDefs.KM_TAG_MIN_SECONDS_BETWEEN_OPS,
-                    spec.getMinSecondsBetweenOperations());
-        }
-        if (spec.getUserAuthenticators().isEmpty()) {
+        if (spec.getUserAuthenticators() == 0) {
             args.addBoolean(KeymasterDefs.KM_TAG_NO_AUTH_REQUIRED);
         } else {
             args.addInt(KeymasterDefs.KM_TAG_USER_AUTH_TYPE,
                     KeyStoreKeyConstraints.UserAuthenticator.allToKeymaster(
                             spec.getUserAuthenticators()));
         }
-        if (spec.getUserAuthenticationValidityDurationSeconds() != null) {
+        if (spec.getUserAuthenticationValidityDurationSeconds() != -1) {
             args.addInt(KeymasterDefs.KM_TAG_AUTH_TIMEOUT,
                     spec.getUserAuthenticationValidityDurationSeconds());
         }
diff --git a/keystore/java/android/security/KeyStoreKeySpec.java b/keystore/java/android/security/KeyStoreKeySpec.java
index ddeefbd..df4c958 100644
--- a/keystore/java/android/security/KeyStoreKeySpec.java
+++ b/keystore/java/android/security/KeyStoreKeySpec.java
@@ -17,10 +17,7 @@
 package android.security;
 
 import java.security.spec.KeySpec;
-import java.util.Collections;
 import java.util.Date;
-import java.util.HashSet;
-import java.util.Set;
 
 /**
  * Information about a key from the <a href="{@docRoot}training/articles/keystore.html">Android
@@ -37,14 +34,12 @@ public class KeyStoreKeySpec implements KeySpec {
     private final Date mKeyValidityForConsumptionEnd;
     private final @KeyStoreKeyConstraints.PurposeEnum int mPurposes;
     private final @KeyStoreKeyConstraints.AlgorithmEnum int mAlgorithm;
-    private final @KeyStoreKeyConstraints.PaddingEnum Integer mPadding;
-    private final @KeyStoreKeyConstraints.DigestEnum Integer mDigest;
-    private final @KeyStoreKeyConstraints.BlockModeEnum Integer mBlockMode;
-    private final Integer mMinSecondsBetweenOperations;
-    private final Integer mMaxUsesPerBoot;
-    private final Set<Integer> mUserAuthenticators;
-    private final Set<Integer> mTeeBackedUserAuthenticators;
-    private final Integer mUserAuthenticationValidityDurationSeconds;
+    private final @KeyStoreKeyConstraints.PaddingEnum int mPaddings;
+    private final @KeyStoreKeyConstraints.DigestEnum int mDigests;
+    private final @KeyStoreKeyConstraints.BlockModeEnum int mBlockModes;
+    private final @KeyStoreKeyConstraints.UserAuthenticatorEnum int mUserAuthenticators;
+    private final @KeyStoreKeyConstraints.UserAuthenticatorEnum int mTeeEnforcedUserAuthenticators;
+    private final int mUserAuthenticationValidityDurationSeconds;
 
 
     /**
@@ -52,18 +47,18 @@ public class KeyStoreKeySpec implements KeySpec {
      */
     KeyStoreKeySpec(String keystoreKeyAlias,
             @KeyStoreKeyCharacteristics.OriginEnum int origin,
-            int keySize, Date keyValidityStart, Date keyValidityForOriginationEnd,
+            int keySize,
+            Date keyValidityStart,
+            Date keyValidityForOriginationEnd,
             Date keyValidityForConsumptionEnd,
             @KeyStoreKeyConstraints.PurposeEnum int purposes,
             @KeyStoreKeyConstraints.AlgorithmEnum int algorithm,
-            @KeyStoreKeyConstraints.PaddingEnum Integer padding,
-            @KeyStoreKeyConstraints.DigestEnum Integer digest,
-            @KeyStoreKeyConstraints.BlockModeEnum Integer blockMode,
-            Integer minSecondsBetweenOperations,
-            Integer maxUsesPerBoot,
-            Set<Integer> userAuthenticators,
-            Set<Integer> teeBackedUserAuthenticators,
-            Integer userAuthenticationValidityDurationSeconds) {
+            @KeyStoreKeyConstraints.PaddingEnum int paddings,
+            @KeyStoreKeyConstraints.DigestEnum int digests,
+            @KeyStoreKeyConstraints.BlockModeEnum int blockModes,
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators,
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum int teeEnforcedUserAuthenticators,
+            int userAuthenticationValidityDurationSeconds) {
         mKeystoreAlias = keystoreKeyAlias;
         mOrigin = origin;
         mKeySize = keySize;
@@ -72,17 +67,11 @@ public class KeyStoreKeySpec implements KeySpec {
         mKeyValidityForConsumptionEnd = keyValidityForConsumptionEnd;
         mPurposes = purposes;
         mAlgorithm = algorithm;
-        mPadding = padding;
-        mDigest = digest;
-        mBlockMode = blockMode;
-        mMinSecondsBetweenOperations = minSecondsBetweenOperations;
-        mMaxUsesPerBoot = maxUsesPerBoot;
-        mUserAuthenticators = (userAuthenticators != null)
-                ? new HashSet<Integer>(userAuthenticators)
-                : Collections.<Integer>emptySet();
-        mTeeBackedUserAuthenticators = (teeBackedUserAuthenticators != null)
-                ? new HashSet<Integer>(teeBackedUserAuthenticators)
-                : Collections.<Integer>emptySet();
+        mPaddings = paddings;
+        mDigests = digests;
+        mBlockModes = blockModes;
+        mUserAuthenticators = userAuthenticators;
+        mTeeEnforcedUserAuthenticators = teeEnforcedUserAuthenticators;
         mUserAuthenticationValidityDurationSeconds = userAuthenticationValidityDurationSeconds;
     }
 
@@ -101,7 +90,7 @@ public class KeyStoreKeySpec implements KeySpec {
     }
 
     /**
-     * Gets the key's size in bits.
+     * Gets the size of the key in bits.
      */
     public int getKeySize() {
         return mKeySize;
@@ -149,78 +138,53 @@ public class KeyStoreKeySpec implements KeySpec {
     }
 
     /**
-     * Gets the only block mode with which the key can be used.
-     *
-     * @return block mode or {@code null} if the block mode is not restricted.
+     * Gets the set of block modes with which the key can be used.
      */
-    public @KeyStoreKeyConstraints.BlockModeEnum Integer getBlockMode() {
-        return mBlockMode;
+    public @KeyStoreKeyConstraints.BlockModeEnum int getBlockModes() {
+        return mBlockModes;
     }
 
     /**
-     * Gets the only padding mode with which the key can be used.
-     *
-     * @return padding mode or {@code null} if the padding mode is not restricted.
-     */
-    public @KeyStoreKeyConstraints.PaddingEnum Integer getPadding() {
-        return mPadding;
-    }
-
-    /**
-     * Gets the only digest algorithm with which the key can be used.
-     *
-     * @return digest algorithm or {@code null} if the digest algorithm is not restricted.
+     * Gets the set of padding modes with which the key can be used.
      */
-    public @KeyStoreKeyConstraints.DigestEnum Integer getDigest() {
-        return mDigest;
+    public @KeyStoreKeyConstraints.PaddingEnum int getPaddings() {
+        return mPaddings;
     }
 
     /**
-     * Gets the minimum number of seconds that must expire since the most recent use of the key
-     * before it can be used again.
-     *
-     * @return number of seconds or {@code null} if there is no restriction on how frequently a key
-     *         can be used.
-     */
-    public Integer getMinSecondsBetweenOperations() {
-        return mMinSecondsBetweenOperations;
-    }
-
-    /**
-     * Gets the number of times the key can be used without rebooting the device.
-     *
-     * @return maximum number of times or {@code null} if there is no restriction.
+     * Gets the set of digest algorithms with which the key can be used.
      */
-    public Integer getMaxUsesPerBoot() {
-        return mMaxUsesPerBoot;
+    public @KeyStoreKeyConstraints.DigestEnum int getDigests() {
+        return mDigests;
     }
 
     /**
-     * Gets the user authenticators which protect access to the key. The key can only be used iff
-     * the user has authenticated to at least one of these user authenticators.
+     * Gets the set of user authenticators which protect access to the key. The key can only be used
+     * iff the user has authenticated to at least one of these user authenticators.
      *
-     * @return user authenticators or empty set if the key can be used without user authentication.
+     * @return user authenticators or {@code 0} if the key can be used without user authentication.
      */
-    public Set<Integer> getUserAuthenticators() {
-        return new HashSet<Integer>(mUserAuthenticators);
+    public @KeyStoreKeyConstraints.UserAuthenticatorEnum int getUserAuthenticators() {
+        return mUserAuthenticators;
     }
 
     /**
-     * Gets the TEE-backed user authenticators which protect access to the key. This is a subset of
-     * the user authentications returned by {@link #getUserAuthenticators()}.
+     * Gets the set of user authenticators for which the TEE enforces access restrictions for this
+     * key. This is a subset of the user authentications returned by
+     * {@link #getUserAuthenticators()}.
      */
-    public Set<Integer> getTeeBackedUserAuthenticators() {
-        return new HashSet<Integer>(mTeeBackedUserAuthenticators);
+    public @KeyStoreKeyConstraints.UserAuthenticatorEnum int getTeeEnforcedUserAuthenticators() {
+        return mTeeEnforcedUserAuthenticators;
     }
 
     /**
      * Gets the duration of time (seconds) for which the key can be used after the user
      * successfully authenticates to one of the associated user authenticators.
      *
-     * @return duration in seconds or {@code null} if not restricted. {@code 0} means authentication
+     * @return duration in seconds or {@code -1} if not restricted. {@code 0} means authentication
      *         is required for every use of the key.
      */
-    public Integer getUserAuthenticationValidityDurationSeconds() {
+    public int getUserAuthenticationValidityDurationSeconds() {
         return mUserAuthenticationValidityDurationSeconds;
     }
 }
diff --git a/keystore/java/android/security/KeyStoreParameter.java b/keystore/java/android/security/KeyStoreParameter.java
index 998e1d9..4909467 100644
--- a/keystore/java/android/security/KeyStoreParameter.java
+++ b/keystore/java/android/security/KeyStoreParameter.java
@@ -18,12 +18,10 @@ package android.security;
 
 import android.content.Context;
 
+import java.security.Key;
 import java.security.KeyPairGenerator;
 import java.security.KeyStore.ProtectionParameter;
-import java.util.Collections;
 import java.util.Date;
-import java.util.HashSet;
-import java.util.Set;
 
 /**
  * This provides the optional parameters that can be specified for
@@ -50,31 +48,25 @@ public final class KeyStoreParameter implements ProtectionParameter {
     private final Date mKeyValidityStart;
     private final Date mKeyValidityForOriginationEnd;
     private final Date mKeyValidityForConsumptionEnd;
-    private final @KeyStoreKeyConstraints.PurposeEnum Integer mPurposes;
-    private final @KeyStoreKeyConstraints.AlgorithmEnum Integer mAlgorithm;
-    private final @KeyStoreKeyConstraints.PaddingEnum Integer mPadding;
-    private final @KeyStoreKeyConstraints.DigestEnum Integer mDigest;
-    private final @KeyStoreKeyConstraints.BlockModeEnum Integer mBlockMode;
-    private final Integer mMinSecondsBetweenOperations;
-    private final Integer mMaxUsesPerBoot;
-    private final Set<Integer> mUserAuthenticators;
-    private final Integer mUserAuthenticationValidityDurationSeconds;
+    private final @KeyStoreKeyConstraints.PurposeEnum int mPurposes;
+    private final @KeyStoreKeyConstraints.PaddingEnum int mPaddings;
+    private final @KeyStoreKeyConstraints.DigestEnum Integer mDigests;
+    private final @KeyStoreKeyConstraints.BlockModeEnum int mBlockModes;
+    private final @KeyStoreKeyConstraints.UserAuthenticatorEnum int mUserAuthenticators;
+    private final int mUserAuthenticationValidityDurationSeconds;
 
     private KeyStoreParameter(int flags,
             Date keyValidityStart,
             Date keyValidityForOriginationEnd,
             Date keyValidityForConsumptionEnd,
-            @KeyStoreKeyConstraints.PurposeEnum Integer purposes,
-            @KeyStoreKeyConstraints.AlgorithmEnum Integer algorithm,
-            @KeyStoreKeyConstraints.PaddingEnum Integer padding,
-            @KeyStoreKeyConstraints.DigestEnum Integer digest,
-            @KeyStoreKeyConstraints.BlockModeEnum Integer blockMode,
-            Integer minSecondsBetweenOperations,
-            Integer maxUsesPerBoot,
-            Set<Integer> userAuthenticators,
-            Integer userAuthenticationValidityDurationSeconds) {
-        if ((userAuthenticationValidityDurationSeconds != null)
-                && (userAuthenticationValidityDurationSeconds < 0)) {
+            @KeyStoreKeyConstraints.PurposeEnum int purposes,
+            @KeyStoreKeyConstraints.PaddingEnum int paddings,
+            @KeyStoreKeyConstraints.DigestEnum Integer digests,
+            @KeyStoreKeyConstraints.BlockModeEnum int blockModes,
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators,
+            int userAuthenticationValidityDurationSeconds) {
+        if ((userAuthenticationValidityDurationSeconds < 0)
+                && (userAuthenticationValidityDurationSeconds != -1)) {
             throw new IllegalArgumentException(
                     "userAuthenticationValidityDurationSeconds must not be negative");
         }
@@ -84,15 +76,10 @@ public final class KeyStoreParameter implements ProtectionParameter {
         mKeyValidityForOriginationEnd = keyValidityForOriginationEnd;
         mKeyValidityForConsumptionEnd = keyValidityForConsumptionEnd;
         mPurposes = purposes;
-        mAlgorithm = algorithm;
-        mPadding = padding;
-        mDigest = digest;
-        mBlockMode = blockMode;
-        mMinSecondsBetweenOperations = minSecondsBetweenOperations;
-        mMaxUsesPerBoot = maxUsesPerBoot;
-        mUserAuthenticators = (userAuthenticators != null)
-                ? new HashSet<Integer>(userAuthenticators)
-                : Collections.<Integer>emptySet();
+        mPaddings = paddings;
+        mDigests = digests;
+        mBlockModes = blockModes;
+        mUserAuthenticators = userAuthenticators;
         mUserAuthenticationValidityDurationSeconds = userAuthenticationValidityDurationSeconds;
     }
 
@@ -144,105 +131,81 @@ public final class KeyStoreParameter implements ProtectionParameter {
     }
 
     /**
-     * Gets the set of purposes for which the key can be used to the provided set of purposes.
-     *
-     * @return set of purposes or {@code null} if the key can be used for any purpose.
+     * Gets the set of purposes for which the key can be used.
      *
      * @hide
      */
-    public @KeyStoreKeyConstraints.PurposeEnum Integer getPurposes() {
+    public @KeyStoreKeyConstraints.PurposeEnum int getPurposes() {
         return mPurposes;
     }
 
     /**
-     * Gets the algorithm to which the key is restricted.
+     * Gets the set of padding schemes to which the key is restricted.
      *
-     * @return algorithm or {@code null} if it's not restricted.
      * @hide
      */
-    public @KeyStoreKeyConstraints.AlgorithmEnum Integer getAlgorithm() {
-        return mAlgorithm;
+    public @KeyStoreKeyConstraints.PaddingEnum int getPaddings() {
+        return mPaddings;
     }
 
     /**
-     * Gets the padding scheme to which the key is restricted.
+     * Gets the set of digests to which the key is restricted.
      *
-     * @return padding scheme or {@code null} if the padding scheme is not restricted.
+     * @throws IllegalStateException if this restriction has not been specified.
      *
-     * @hide
-     */
-    public @KeyStoreKeyConstraints.PaddingEnum Integer getPadding() {
-        return mPadding;
-    }
-
-    /**
-     * Gets the digest to which the key is restricted when generating signatures or Message
-     * Authentication Codes (MACs).
-     *
-     * @return digest or {@code null} if the digest is not restricted.
+     * @see #isDigestsSpecified()
      *
      * @hide
      */
-    public @KeyStoreKeyConstraints.DigestEnum Integer getDigest() {
-        return mDigest;
-    }
-
-    /**
-     * Gets the block mode to which the key is restricted when used for encryption or decryption.
-     *
-     * @return block more or {@code null} if block mode is not restricted.
-     *
-     * @hide
-     */
-    public @KeyStoreKeyConstraints.BlockModeEnum Integer getBlockMode() {
-        return mBlockMode;
+    public @KeyStoreKeyConstraints.DigestEnum int getDigests() {
+        if (mDigests == null) {
+            throw new IllegalStateException("Digests not specified");
+        }
+        return mDigests;
     }
 
     /**
-     * Gets the minimum number of seconds that must expire since the most recent use of the key
-     * before it can be used again.
+     * Returns {@code true} if digest restrictions have been specified.
      *
-     * @return number of seconds or {@code null} if there is no restriction on how frequently a key
-     *         can be used.
+     * @see #getDigests()
      *
      * @hide
      */
-    public Integer getMinSecondsBetweenOperations() {
-        return mMinSecondsBetweenOperations;
+    public boolean isDigestsSpecified() {
+        return mDigests != null;
     }
 
     /**
-     * Gets the number of times the key can be used without rebooting the device.
+     * Gets the set of block modes to which the key is restricted.
      *
-     * @return maximum number of times or {@code null} if there is no restriction.
      * @hide
      */
-    public Integer getMaxUsesPerBoot() {
-        return mMaxUsesPerBoot;
+    public @KeyStoreKeyConstraints.BlockModeEnum int getBlockModes() {
+        return mBlockModes;
     }
 
     /**
-     * Gets the user authenticators which protect access to this key. The key can only be used iff
-     * the user has authenticated to at least one of these user authenticators.
+     * Gets the set of user authenticators which protect access to this key. The key can only be
+     * used iff the user has authenticated to at least one of these user authenticators.
      *
-     * @return user authenticators or empty set if the key can be used without user authentication.
+     * @return user authenticators or {@code 0} if the key can be used without user authentication.
      *
      * @hide
      */
-    public Set<Integer> getUserAuthenticators() {
-        return new HashSet<Integer>(mUserAuthenticators);
+    public @KeyStoreKeyConstraints.UserAuthenticatorEnum int getUserAuthenticators() {
+        return mUserAuthenticators;
     }
 
     /**
      * Gets the duration of time (seconds) for which this key can be used after the user
      * successfully authenticates to one of the associated user authenticators.
      *
-     * @return duration in seconds or {@code null} if not restricted. {@code 0} means authentication
+     * @return duration in seconds or {@code -1} if not restricted. {@code 0} means authentication
      *         is required for every use of the key.
      *
      * @hide
      */
-    public Integer getUserAuthenticationValidityDurationSeconds() {
+    public int getUserAuthenticationValidityDurationSeconds() {
         return mUserAuthenticationValidityDurationSeconds;
     }
 
@@ -268,15 +231,12 @@ public final class KeyStoreParameter implements ProtectionParameter {
         private Date mKeyValidityStart;
         private Date mKeyValidityForOriginationEnd;
         private Date mKeyValidityForConsumptionEnd;
-        private @KeyStoreKeyConstraints.PurposeEnum Integer mPurposes;
-        private @KeyStoreKeyConstraints.AlgorithmEnum Integer mAlgorithm;
-        private @KeyStoreKeyConstraints.PaddingEnum Integer mPadding;
-        private @KeyStoreKeyConstraints.DigestEnum Integer mDigest;
-        private @KeyStoreKeyConstraints.BlockModeEnum Integer mBlockMode;
-        private Integer mMinSecondsBetweenOperations;
-        private Integer mMaxUsesPerBoot;
-        private Set<Integer> mUserAuthenticators;
-        private Integer mUserAuthenticationValidityDurationSeconds;
+        private @KeyStoreKeyConstraints.PurposeEnum int mPurposes;
+        private @KeyStoreKeyConstraints.PaddingEnum int mPaddings;
+        private @KeyStoreKeyConstraints.DigestEnum Integer mDigests;
+        private @KeyStoreKeyConstraints.BlockModeEnum int mBlockModes;
+        private @KeyStoreKeyConstraints.UserAuthenticatorEnum int mUserAuthenticators;
+        private int mUserAuthenticationValidityDurationSeconds = -1;
 
         /**
          * Creates a new instance of the {@code Builder} with the given
@@ -368,9 +328,9 @@ public final class KeyStoreParameter implements ProtectionParameter {
         }
 
         /**
-         * Restricts the purposes for which the key can be used to the provided set of purposes.
+         * Restricts the key to being used only for the provided set of purposes.
          *
-         * <p>By default, the key can be used for encryption, decryption, signing, and verification.
+         * <p>This restriction must be specified. There is no default.
          *
          * @hide
          */
@@ -380,84 +340,43 @@ public final class KeyStoreParameter implements ProtectionParameter {
         }
 
         /**
-         * Sets the algorithm of the key.
-         *
-         * <p>The algorithm of symmetric keys can be deduced from the key itself. Thus, explicitly
-         * specifying the algorithm of symmetric keys using this method is not necessary.
-         *
-         * @hide
-         */
-        public Builder setAlgorithm(@KeyStoreKeyConstraints.AlgorithmEnum int algorithm) {
-            mAlgorithm = algorithm;
-            return this;
-        }
-
-        /**
-         * Restricts the key to being used only with the provided padding scheme. Attempts to use
+         * Restricts the key to being used only with the provided padding schemes. Attempts to use
          * the key with any other padding will be rejected.
          *
          * <p>This restriction must be specified for keys which are used for encryption/decryption.
          *
          * @hide
          */
-        public Builder setPadding(@KeyStoreKeyConstraints.PaddingEnum int padding) {
-            mPadding = padding;
-            return this;
-        }
-
-        /**
-         * Restricts the key to being used only with the provided digest when generating signatures
-         * or Message Authentication Codes (MACs). Attempts to use the key with any other digest
-         * will be rejected.
-         *
-         * <p>For MAC keys, the default is to restrict to the digest specified in the key algorithm
-         * name. For asymmetric signing keys this constraint must be specified because there is no
-         * default.
-         *
-         * @see java.security.Key#getAlgorithm()
-         *
-         * @hide
-         */
-        public Builder setDigest(@KeyStoreKeyConstraints.DigestEnum int digest) {
-            mDigest = digest;
-            return this;
-        }
-
-        /**
-         * Restricts the key to being used only with the provided block mode when encrypting or
-         * decrypting. Attempts to use the key with any other block modes will be rejected.
-         *
-         * <p>This restriction must be specified for keys which are used for encryption/decryption.
-         *
-         * @hide
-         */
-        public Builder setBlockMode(@KeyStoreKeyConstraints.BlockModeEnum int blockMode) {
-            mBlockMode = blockMode;
+        public Builder setPaddings(@KeyStoreKeyConstraints.PaddingEnum int paddings) {
+            mPaddings = paddings;
             return this;
         }
 
         /**
-         * Sets the minimum number of seconds that must expire since the most recent use of the key
-         * before it can be used again.
+         * Restricts the key to being used only with the provided digests when generating signatures
+         * or HMACs. Attempts to use the key with any other digest will be rejected.
          *
-         * <p>By default, there is no restriction on how frequently a key can be used.
+         * <p>For HMAC keys, the default is to restrict to the digest specified in
+         * {@link Key#getAlgorithm()}. For asymmetric signing keys this constraint must be specified
+         * because there is no default.
          *
          * @hide
          */
-        public Builder setMinSecondsBetweenOperations(int seconds) {
-            mMinSecondsBetweenOperations = seconds;
+        public Builder setDigests(@KeyStoreKeyConstraints.DigestEnum int digests) {
+            mDigests = digests;
             return this;
         }
 
         /**
-         * Sets the maximum number of times a key can be used without rebooting the device.
+         * Restricts the key to being used only with the provided block modes. Attempts to use the
+         * key with any other block modes will be rejected.
          *
-         * <p>By default, the key can be used for an unlimited number of times.
+         * <p>This restriction must be specified for symmetric encryption/decryption keys.
          *
          * @hide
          */
-        public Builder setMaxUsesPerBoot(int count) {
-            mMaxUsesPerBoot = count;
+        public Builder setBlockModes(@KeyStoreKeyConstraints.BlockModeEnum int blockModes) {
+            mBlockModes = blockModes;
             return this;
         }
 
@@ -467,16 +386,16 @@ public final class KeyStoreParameter implements ProtectionParameter {
          *
          * <p>By default, the key can be used without user authentication.
          *
-         * @param userAuthenticators user authenticators or empty list if this key can be accessed
+         * @param userAuthenticators user authenticators or {@code 0} if this key can be accessed
          *        without user authentication.
          *
          * @see #setUserAuthenticationValidityDurationSeconds(int)
          *
          * @hide
          */
-        public Builder setUserAuthenticators(Set<Integer> userAuthenticators) {
-            mUserAuthenticators =
-                    (userAuthenticators != null) ? new HashSet<Integer>(userAuthenticators) : null;
+        public Builder setUserAuthenticators(
+                @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators) {
+            mUserAuthenticators = userAuthenticators;
             return this;
         }
 
@@ -489,7 +408,7 @@ public final class KeyStoreParameter implements ProtectionParameter {
          * @param seconds duration in seconds or {@code 0} if the user needs to authenticate for
          *        every use of the key.
          *
-         * @see #setUserAuthenticators(Set)
+         * @see #setUserAuthenticators(int)
          *
          * @hide
          */
@@ -510,12 +429,9 @@ public final class KeyStoreParameter implements ProtectionParameter {
                     mKeyValidityForOriginationEnd,
                     mKeyValidityForConsumptionEnd,
                     mPurposes,
-                    mAlgorithm,
-                    mPadding,
-                    mDigest,
-                    mBlockMode,
-                    mMinSecondsBetweenOperations,
-                    mMaxUsesPerBoot,
+                    mPaddings,
+                    mDigests,
+                    mBlockModes,
                     mUserAuthenticators,
                     mUserAuthenticationValidityDurationSeconds);
         }
diff --git a/keystore/java/android/security/KeyStoreSecretKeyFactorySpi.java b/keystore/java/android/security/KeyStoreSecretKeyFactorySpi.java
index f552759..09f0b00 100644
--- a/keystore/java/android/security/KeyStoreSecretKeyFactorySpi.java
+++ b/keystore/java/android/security/KeyStoreSecretKeyFactorySpi.java
@@ -23,7 +23,6 @@ import java.security.InvalidKeyException;
 import java.security.spec.InvalidKeySpecException;
 import java.security.spec.KeySpec;
 import java.util.Date;
-import java.util.Set;
 
 import javax.crypto.SecretKey;
 import javax.crypto.SecretKeyFactorySpi;
@@ -75,9 +74,11 @@ public class KeyStoreSecretKeyFactorySpi extends SecretKeyFactorySpi {
         int keySize;
         @KeyStoreKeyConstraints.PurposeEnum int purposes;
         @KeyStoreKeyConstraints.AlgorithmEnum int algorithm;
-        @KeyStoreKeyConstraints.PaddingEnum Integer padding;
-        @KeyStoreKeyConstraints.DigestEnum Integer digest;
-        @KeyStoreKeyConstraints.BlockModeEnum Integer blockMode;
+        @KeyStoreKeyConstraints.PaddingEnum int paddings;
+        @KeyStoreKeyConstraints.DigestEnum int digests;
+        @KeyStoreKeyConstraints.BlockModeEnum int blockModes;
+        @KeyStoreKeyConstraints.UserAuthenticatorEnum int userAuthenticators;
+        @KeyStoreKeyConstraints.UserAuthenticatorEnum int teeEnforcedUserAuthenticators;
         try {
             origin = KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_ORIGIN);
             if (origin == null) {
@@ -97,18 +98,27 @@ public class KeyStoreSecretKeyFactorySpi extends SecretKeyFactorySpi {
                 throw new InvalidKeySpecException("Key algorithm not available");
             }
             algorithm = KeyStoreKeyConstraints.Algorithm.fromKeymaster(alg);
-            padding = KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_PADDING);
-            if (padding != null) {
-                padding = KeyStoreKeyConstraints.Padding.fromKeymaster(padding);
-            }
-            digest = KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_DIGEST);
-            if (digest != null) {
-                digest = KeyStoreKeyConstraints.Digest.fromKeymaster(digest);
-            }
-            blockMode = KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_BLOCK_MODE);
-            if (blockMode != null) {
-                blockMode = KeyStoreKeyConstraints.BlockMode.fromKeymaster(blockMode);
-            }
+            paddings = KeyStoreKeyConstraints.Padding.allFromKeymaster(
+                    KeymasterUtils.getInts(keyCharacteristics, KeymasterDefs.KM_TAG_PADDING));
+            digests = KeyStoreKeyConstraints.Digest.allFromKeymaster(
+                    KeymasterUtils.getInts(keyCharacteristics, KeymasterDefs.KM_TAG_DIGEST));
+            blockModes = KeyStoreKeyConstraints.BlockMode.allFromKeymaster(
+                    KeymasterUtils.getInts(keyCharacteristics, KeymasterDefs.KM_TAG_BLOCK_MODE));
+
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum
+            int swEnforcedKeymasterUserAuthenticators =
+                    keyCharacteristics.swEnforced.getInt(KeymasterDefs.KM_TAG_USER_AUTH_TYPE, 0);
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum
+            int hwEnforcedKeymasterUserAuthenticators =
+                    keyCharacteristics.hwEnforced.getInt(KeymasterDefs.KM_TAG_USER_AUTH_TYPE, 0);
+            @KeyStoreKeyConstraints.UserAuthenticatorEnum
+            int keymasterUserAuthenticators =
+                    swEnforcedKeymasterUserAuthenticators | hwEnforcedKeymasterUserAuthenticators;
+            userAuthenticators = KeyStoreKeyConstraints.UserAuthenticator.allFromKeymaster(
+                    keymasterUserAuthenticators);
+            teeEnforcedUserAuthenticators =
+                    KeyStoreKeyConstraints.UserAuthenticator.allFromKeymaster(
+                            hwEnforcedKeymasterUserAuthenticators);
         } catch (IllegalArgumentException e) {
             throw new InvalidKeySpecException("Unsupported key characteristic", e);
         }
@@ -130,17 +140,8 @@ public class KeyStoreSecretKeyFactorySpi extends SecretKeyFactorySpi {
                 && (keyValidityForConsumptionEnd.getTime() == Long.MAX_VALUE)) {
             keyValidityForConsumptionEnd = null;
         }
-
-        int swEnforcedUserAuthenticatorIds =
-                keyCharacteristics.swEnforced.getInt(KeymasterDefs.KM_TAG_USER_AUTH_TYPE, 0);
-        int hwEnforcedUserAuthenticatorIds =
-                keyCharacteristics.hwEnforced.getInt(KeymasterDefs.KM_TAG_USER_AUTH_TYPE, 0);
-        int userAuthenticatorIds = swEnforcedUserAuthenticatorIds | hwEnforcedUserAuthenticatorIds;
-        Set<Integer> userAuthenticators =
-                KeyStoreKeyConstraints.UserAuthenticator.allFromKeymaster(userAuthenticatorIds);
-        Set<Integer> teeBackedUserAuthenticators =
-                KeyStoreKeyConstraints.UserAuthenticator.allFromKeymaster(
-                        hwEnforcedUserAuthenticatorIds);
+        Integer userAuthenticationValidityDurationSeconds =
+                KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_AUTH_TIMEOUT);
 
         return new KeyStoreKeySpec(entryAlias,
                 origin,
@@ -150,15 +151,13 @@ public class KeyStoreSecretKeyFactorySpi extends SecretKeyFactorySpi {
                 keyValidityForConsumptionEnd,
                 purposes,
                 algorithm,
-                padding,
-                digest,
-                blockMode,
-                KeymasterUtils.getInt(keyCharacteristics,
-                        KeymasterDefs.KM_TAG_MIN_SECONDS_BETWEEN_OPS),
-                KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_MAX_USES_PER_BOOT),
+                paddings,
+                digests,
+                blockModes,
                 userAuthenticators,
-                teeBackedUserAuthenticators,
-                KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_AUTH_TIMEOUT));
+                teeEnforcedUserAuthenticators,
+                ((userAuthenticationValidityDurationSeconds != null)
+                        ? userAuthenticationValidityDurationSeconds : -1));
     }
 
     @Override