Merge "Add SecretKeyFactory backed by AndroidKeyStore."

6 files changed, 445 insertions, 1 deletions

diff --git a/keystore/java/android/security/AndroidKeyStoreProvider.java b/keystore/java/android/security/AndroidKeyStoreProvider.java
index 6cf9b7a..39f9d9c 100644
--- a/keystore/java/android/security/AndroidKeyStoreProvider.java
+++ b/keystore/java/android/security/AndroidKeyStoreProvider.java
@@ -40,6 +40,10 @@ public class AndroidKeyStoreProvider extends Provider {
         put("KeyGenerator.AES", KeyStoreKeyGeneratorSpi.AES.class.getName());
         put("KeyGenerator.HmacSHA256", KeyStoreKeyGeneratorSpi.HmacSHA256.class.getName());
 
+        // java.security.SecretKeyFactory
+        put("SecretKeyFactory.AES", KeyStoreSecretKeyFactorySpi.class.getName());
+        put("SecretKeyFactory.HmacSHA256", KeyStoreSecretKeyFactorySpi.class.getName());
+
         // javax.crypto.Mac
         putMacImpl("HmacSHA256", KeyStoreHmacSpi.HmacSHA256.class.getName());
 
diff --git a/keystore/java/android/security/KeyGeneratorSpec.java b/keystore/java/android/security/KeyGeneratorSpec.java
index 6274b70..61573f2 100644
--- a/keystore/java/android/security/KeyGeneratorSpec.java
+++ b/keystore/java/android/security/KeyGeneratorSpec.java
@@ -146,7 +146,7 @@ public class KeyGeneratorSpec implements AlgorithmParameterSpec {
     }
 
     /**
-     * Gets the set of purposes for which the key can be used to the provided set of purposes.
+     * 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.
      */
diff --git a/keystore/java/android/security/KeyStoreKeyCharacteristics.java b/keystore/java/android/security/KeyStoreKeyCharacteristics.java
new file mode 100644
index 0000000..c06dc3b
--- /dev/null
+++ b/keystore/java/android/security/KeyStoreKeyCharacteristics.java
@@ -0,0 +1,52 @@
+package android.security;
+
+import android.annotation.IntDef;
+import android.security.keymaster.KeymasterDefs;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Characteristics of {@code AndroidKeyStore} keys.
+ *
+ * @hide
+ */
+public abstract class KeyStoreKeyCharacteristics {
+    private KeyStoreKeyCharacteristics() {}
+
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef({Origin.GENERATED_INSIDE_TEE, Origin.GENERATED_OUTSIDE_OF_TEE, Origin.IMPORTED})
+    public @interface OriginEnum {}
+
+    /**
+     * Origin of the key.
+     */
+    public static abstract class Origin {
+        private Origin() {}
+
+        /** Key was generated inside a TEE. */
+        public static final int GENERATED_INSIDE_TEE = 1;
+
+        /** Key was generated outside of a TEE. */
+        public static final int GENERATED_OUTSIDE_OF_TEE = 2;
+
+        /** Key was imported. */
+        public static final int IMPORTED = 0;
+
+        /**
+         * @hide
+         */
+        public static @OriginEnum int fromKeymaster(int origin) {
+            switch (origin) {
+                case KeymasterDefs.KM_ORIGIN_HARDWARE:
+                    return GENERATED_INSIDE_TEE;
+                case KeymasterDefs.KM_ORIGIN_SOFTWARE:
+                    return GENERATED_OUTSIDE_OF_TEE;
+                case KeymasterDefs.KM_ORIGIN_IMPORTED:
+                    return IMPORTED;
+                default:
+                    throw new IllegalArgumentException("Unknown origin: " + origin);
+            }
+        }
+    }
+}
diff --git a/keystore/java/android/security/KeyStoreKeySpec.java b/keystore/java/android/security/KeyStoreKeySpec.java
new file mode 100644
index 0000000..19fba68
--- /dev/null
+++ b/keystore/java/android/security/KeyStoreKeySpec.java
@@ -0,0 +1,210 @@
+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
+ * KeyStore</a>.
+ *
+ * @hide
+ */
+public class KeyStoreKeySpec implements KeySpec {
+    private final String mKeystoreAlias;
+    private final int mKeySize;
+    private final @KeyStoreKeyCharacteristics.OriginEnum int mOrigin;
+    private final Date mKeyValidityStart;
+    private final Date mKeyValidityForOriginationEnd;
+    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;
+
+
+    /**
+     * @hide
+     */
+    KeyStoreKeySpec(String keystoreKeyAlias,
+            @KeyStoreKeyCharacteristics.OriginEnum int origin,
+            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) {
+        mKeystoreAlias = keystoreKeyAlias;
+        mOrigin = origin;
+        mKeySize = keySize;
+        mKeyValidityStart = keyValidityStart;
+        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();
+        mTeeBackedUserAuthenticators = (teeBackedUserAuthenticators != null)
+                ? new HashSet<Integer>(teeBackedUserAuthenticators)
+                : Collections.<Integer>emptySet();
+        mUserAuthenticationValidityDurationSeconds = userAuthenticationValidityDurationSeconds;
+    }
+
+    /**
+     * Gets the entry alias under which the key is stored in the {@code AndroidKeyStore}.
+     */
+    public String getKeystoreAlias() {
+        return mKeystoreAlias;
+    }
+
+    /**
+     * Gets the origin of the key.
+     */
+    public @KeyStoreKeyCharacteristics.OriginEnum int getOrigin() {
+        return mOrigin;
+    }
+
+    /**
+     * Gets the key's size in bits.
+     */
+    public int getKeySize() {
+        return mKeySize;
+    }
+
+    /**
+     * Gets the time instant before which the key is not yet valid.
+     *
+     * @return instant or {@code null} if not restricted.
+     */
+    public Date getKeyValidityStart() {
+        return mKeyValidityStart;
+    }
+
+    /**
+     * Gets the time instant after which the key is no long valid for decryption and verification.
+     *
+     * @return instant or {@code null} if not restricted.
+     */
+    public Date getKeyValidityForConsumptionEnd() {
+        return mKeyValidityForConsumptionEnd;
+    }
+
+    /**
+     * Gets the time instant after which the key is no long valid for encryption and signing.
+     *
+     * @return instant or {@code null} if not restricted.
+     */
+    public Date getKeyValidityForOriginationEnd() {
+        return mKeyValidityForOriginationEnd;
+    }
+
+    /**
+     * Gets the set of purposes for which the key can be used.
+     */
+    public @KeyStoreKeyConstraints.PurposeEnum int getPurposes() {
+        return mPurposes;
+    }
+
+    /**
+     * Gets the algorithm of the key.
+     */
+    public @KeyStoreKeyConstraints.AlgorithmEnum int getAlgorithm() {
+        return mAlgorithm;
+    }
+
+    /**
+     * 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.
+     */
+    public @KeyStoreKeyConstraints.BlockModeEnum Integer getBlockMode() {
+        return mBlockMode;
+    }
+
+    /**
+     * 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.
+     */
+    public @KeyStoreKeyConstraints.DigestEnum Integer getDigest() {
+        return mDigest;
+    }
+
+    /**
+     * 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.
+     */
+    public Integer getMaxUsesPerBoot() {
+        return mMaxUsesPerBoot;
+    }
+
+    /**
+     * 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.
+     *
+     * @return user authenticators or empty set if the key can be used without user authentication.
+     */
+    public Set<Integer> getUserAuthenticators() {
+        return new HashSet<Integer>(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()}.
+     */
+    public Set<Integer> getTeeBackedUserAuthenticators() {
+        return new HashSet<Integer>(mTeeBackedUserAuthenticators);
+    }
+
+    /**
+     * 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
+     *         is required for every use of the key.
+     */
+    public Integer getUserAuthenticationValidityDurationSeconds() {
+        return mUserAuthenticationValidityDurationSeconds;
+    }
+}
diff --git a/keystore/java/android/security/KeyStoreSecretKeyFactorySpi.java b/keystore/java/android/security/KeyStoreSecretKeyFactorySpi.java
new file mode 100644
index 0000000..70e643d
--- /dev/null
+++ b/keystore/java/android/security/KeyStoreSecretKeyFactorySpi.java
@@ -0,0 +1,140 @@
+package android.security;
+
+import android.security.keymaster.KeyCharacteristics;
+import android.security.keymaster.KeymasterDefs;
+
+import java.security.InvalidKeyException;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.KeySpec;
+import java.util.Collections;
+import java.util.Set;
+
+import javax.crypto.SecretKey;
+import javax.crypto.SecretKeyFactorySpi;
+import javax.crypto.spec.SecretKeySpec;
+
+/**
+ * {@link SecretKeyFactorySpi} backed by Android KeyStore.
+ *
+ * @hide
+ */
+public class KeyStoreSecretKeyFactorySpi extends SecretKeyFactorySpi {
+
+    private final KeyStore mKeyStore = KeyStore.getInstance();
+
+    @Override
+    protected KeySpec engineGetKeySpec(SecretKey key,
+            @SuppressWarnings("rawtypes") Class keySpecClass) throws InvalidKeySpecException {
+        if (keySpecClass == null) {
+            throw new InvalidKeySpecException("keySpecClass == null");
+        }
+        if (!(key instanceof KeyStoreSecretKey)) {
+            throw new InvalidKeySpecException("Only Android KeyStore secret keys supported: " +
+                    ((key != null) ? key.getClass().getName() : "null"));
+        }
+        if (SecretKeySpec.class.isAssignableFrom(keySpecClass)) {
+            throw new InvalidKeySpecException(
+                    "Key material export of Android KeyStore keys is not supported");
+        }
+        if (!KeyStoreKeySpec.class.equals(keySpecClass)) {
+            throw new InvalidKeySpecException("Unsupported key spec: " + keySpecClass.getName());
+        }
+        String keyAliasInKeystore = ((KeyStoreSecretKey) key).getAlias();
+        String entryAlias;
+        if (keyAliasInKeystore.startsWith(Credentials.USER_SECRET_KEY)) {
+            entryAlias = keyAliasInKeystore.substring(Credentials.USER_SECRET_KEY.length());
+        } else {
+            throw new InvalidKeySpecException("Invalid key alias: " + keyAliasInKeystore);
+        }
+
+        KeyCharacteristics keyCharacteristics = new KeyCharacteristics();
+        int errorCode =
+                mKeyStore.getKeyCharacteristics(keyAliasInKeystore, null, null, keyCharacteristics);
+        if (errorCode != KeyStore.NO_ERROR) {
+            throw new InvalidKeySpecException("Failed to obtain information about key."
+                    + " Keystore error: " + errorCode);
+        }
+
+        @KeyStoreKeyCharacteristics.OriginEnum Integer origin;
+        int keySize;
+        @KeyStoreKeyConstraints.PurposeEnum int purposes;
+        @KeyStoreKeyConstraints.AlgorithmEnum int algorithm;
+        @KeyStoreKeyConstraints.PaddingEnum Integer padding;
+        @KeyStoreKeyConstraints.DigestEnum Integer digest;
+        @KeyStoreKeyConstraints.BlockModeEnum Integer blockMode;
+        try {
+            origin = KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_ORIGIN);
+            if (origin == null) {
+                throw new InvalidKeySpecException("Key origin not available");
+            }
+            origin = KeyStoreKeyCharacteristics.Origin.fromKeymaster(origin);
+            Integer keySizeInteger =
+                    KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_KEY_SIZE);
+            if (keySizeInteger == null) {
+                throw new InvalidKeySpecException("Key size not available");
+            }
+            keySize = keySizeInteger;
+            purposes = KeyStoreKeyConstraints.Purpose.allFromKeymaster(
+                    KeymasterUtils.getInts(keyCharacteristics, KeymasterDefs.KM_TAG_PURPOSE));
+            Integer alg = KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_ALGORITHM);
+            if (alg == null) {
+                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);
+            }
+        } catch (IllegalArgumentException e) {
+            throw new InvalidKeySpecException("Unsupported key characteristic", e);
+        }
+
+        // TODO: Read user authentication IDs once the Keymaster API has stabilized
+        Set<Integer> userAuthenticators = Collections.emptySet();
+        Set<Integer> teeBackedUserAuthenticators = Collections.emptySet();
+//        Set<Integer> userAuthenticators = new HashSet<Integer>(
+//                getInts(keyCharacteristics, KeymasterDefs.KM_TAG_USER_AUTH_ID));
+//        Set<Integer> teeBackedUserAuthenticators = new HashSet<Integer>(
+//                keyCharacteristics.hwEnforced.getInts(KeymasterDefs.KM_TAG_USER_AUTH_ID));
+
+        return new KeyStoreKeySpec(entryAlias,
+                origin,
+                keySize,
+                KeymasterUtils.getDate(keyCharacteristics, KeymasterDefs.KM_TAG_ACTIVE_DATETIME),
+                KeymasterUtils.getDate(keyCharacteristics,
+                        KeymasterDefs.KM_TAG_ORIGINATION_EXPIRE_DATETIME),
+                KeymasterUtils.getDate(keyCharacteristics,
+                        KeymasterDefs.KM_TAG_USAGE_EXPIRE_DATETIME),
+                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),
+                userAuthenticators,
+                teeBackedUserAuthenticators,
+                KeymasterUtils.getInt(keyCharacteristics, KeymasterDefs.KM_TAG_AUTH_TIMEOUT));
+    }
+
+    @Override
+    protected SecretKey engineGenerateSecret(KeySpec keySpec) throws InvalidKeySpecException {
+        throw new UnsupportedOperationException(
+                "Key import into Android KeyStore is not supported");
+    }
+
+    @Override
+    protected SecretKey engineTranslateKey(SecretKey key) throws InvalidKeyException {
+        throw new UnsupportedOperationException(
+                "Key import into Android KeyStore is not supported");
+    }
+}
diff --git a/keystore/java/android/security/KeymasterUtils.java b/keystore/java/android/security/KeymasterUtils.java
index 4f17586..e9ad69f 100644
--- a/keystore/java/android/security/KeymasterUtils.java
+++ b/keystore/java/android/security/KeymasterUtils.java
@@ -1,7 +1,12 @@
 package android.security;
 
+import android.security.keymaster.KeyCharacteristics;
 import android.security.keymaster.KeymasterDefs;
 
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+
 /**
  * @hide
  */
@@ -20,4 +25,37 @@ public abstract class KeymasterUtils {
                         KeymasterDefs.getErrorMessage(keymasterErrorCode));
         }
     }
+
+    public static Integer getInt(KeyCharacteristics keyCharacteristics, int tag) {
+        if (keyCharacteristics.hwEnforced.containsTag(tag)) {
+            return keyCharacteristics.hwEnforced.getInt(tag, -1);
+        } else if (keyCharacteristics.swEnforced.containsTag(tag)) {
+            return keyCharacteristics.swEnforced.getInt(tag, -1);
+        } else {
+            return null;
+        }
+    }
+
+    public static List<Integer> getInts(KeyCharacteristics keyCharacteristics, int tag) {
+        List<Integer> result = new ArrayList<Integer>();
+        result.addAll(keyCharacteristics.hwEnforced.getInts(tag));
+        result.addAll(keyCharacteristics.swEnforced.getInts(tag));
+        return result;
+    }
+
+    public static Date getDate(KeyCharacteristics keyCharacteristics, int tag) {
+        Date result = keyCharacteristics.hwEnforced.getDate(tag, null);
+        if (result == null) {
+            result = keyCharacteristics.swEnforced.getDate(tag, null);
+        }
+        return result;
+    }
+
+    public static boolean getBoolean(KeyCharacteristics keyCharacteristics, int tag) {
+        if (keyCharacteristics.hwEnforced.containsTag(tag)) {
+            return keyCharacteristics.hwEnforced.getBoolean(tag, false);
+        } else {
+            return keyCharacteristics.swEnforced.getBoolean(tag, false);
+        }
+    }
 }