/* * Copyright (C) 2012 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.security.keystore; import android.annotation.IntRange; import android.annotation.NonNull; import android.annotation.Nullable; import android.app.KeyguardManager; import android.hardware.fingerprint.FingerprintManager; import android.text.TextUtils; import java.math.BigInteger; import java.security.KeyPairGenerator; import java.security.Signature; import java.security.cert.Certificate; import java.security.spec.AlgorithmParameterSpec; import java.util.Date; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.Mac; import javax.security.auth.x500.X500Principal; /** * {@link AlgorithmParameterSpec} for initializing a {@link KeyPairGenerator} or a * {@link KeyGenerator} of the Android Keystore * system. The spec determines authorized uses of the key, such as whether user authentication * is required for using the key, what operations are authorized (e.g., signing, but not * decryption) and with what parameters (e.g., only with a particular padding scheme or digest), the * key's validity start and end dates. Key use authorizations expressed in the spec apply only to * secret keys and private keys -- public keys can be used for any supported operations. * *

To generate an asymmetric key pair or a symmetric key, create an instance of this class using * the {@link Builder}, initialize a {@code KeyPairGenerator} or a {@code KeyGenerator} of the * desired key type (e.g., {@code EC} or {@code AES} -- see * {@link KeyProperties}.{@code KEY_ALGORITHM} constants) from the {@code AndroidKeyStore} provider * with the {@code KeyGenParameterSpec} instance, and then generate a key or key pair using * {@link KeyGenerator#generateKey()} or {@link KeyPairGenerator#generateKeyPair()}. * *

The generated key pair or key will be returned by the generator and also stored in the Android * Keystore under the alias specified in this spec. To obtain the secret or private key from the * Android Keystore use {@link java.security.KeyStore#getKey(String, char[]) KeyStore.getKey(String, null)} * or {@link java.security.KeyStore#getEntry(String, java.security.KeyStore.ProtectionParameter) KeyStore.getEntry(String, null)}. * To obtain the public key from the Android Keystore use * {@link java.security.KeyStore#getCertificate(String)} and then * {@link Certificate#getPublicKey()}. * *

To help obtain algorithm-specific public parameters of key pairs stored in the Android * Keystore, generated private keys implement {@link java.security.interfaces.ECKey} or * {@link java.security.interfaces.RSAKey} interfaces whereas public keys implement * {@link java.security.interfaces.ECPublicKey} or {@link java.security.interfaces.RSAPublicKey} * interfaces. * *

For asymmetric key pairs, a self-signed X.509 certificate will be also generated and stored in * the Android Keystore. This is because the {@link java.security.KeyStore} abstraction does not * support storing key pairs without a certificate. The subject, serial number, and validity dates * of the certificate can be customized in this spec. The self-signed certificate may be replaced at * a later time by a certificate signed by a Certificate Authority (CA). * *

NOTE: If a private key is not authorized to sign the self-signed certificate, then the * certificate will be created with an invalid signature which will not verify. Such a certificate * is still useful because it provides access to the public key. To generate a valid signature for * the certificate the key needs to be authorized for all of the following: *

* *

NOTE: The key material of the generated symmetric and private keys is not accessible. The key * material of the public keys is accessible. * *

Instances of this class are immutable. * *

Example: NIST P-256 EC key pair for signing/verification using ECDSA

* This example illustrates how to generate a NIST P-256 (aka secp256r1 aka prime256v1) EC key pair * in the Android KeyStore system under alias {@code key1} where the private key is authorized to be * used only for signing using SHA-256, SHA-384, or SHA-512 digest and only if the user has been * authenticated within the last five minutes. The use of public key is unrestricted, thus * permitting signature verification using any padding schemes and digests, and without user * authentication. *
 {@code
 * KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(
 *         KeyProperties.KEY_ALGORITHM_EC, "AndroidKeyStore");
 * keyPairGenerator.initialize(
 *         new KeyGenParameterSpec.Builder(
 *                 "key1",
 *                 KeyProperties.PURPOSE_SIGN)
 *                 .setAlgorithmParameterSpec(new ECGenParameterSpec("secp256r1"))
 *                 .setDigests(KeyProperties.DIGEST_SHA256,
 *                         KeyProperties.DIGEST_SHA384,
 *                         KeyProperties.DIGEST_SHA512)
 *                 // Only permit the private key to be used if the user authenticated
 *                 // within the last five minutes.
 *                 .setUserAuthenticationRequired(true)
 *                 .setUserAuthenticationValidityDurationSeconds(5 * 60)
 *                 .build());
 * KeyPair keyPair = keyPairGenerator.generateKeyPair();
 * Signature signature = Signature.getInstance("SHA256withECDSA");
 * signature.initSign(keyPair.getPrivate());
 * ...
 *
 * // The key pair can also be obtained from the Android Keystore any time as follows:
 * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
 * keyStore.load(null);
 * PrivateKey privateKey = (PrivateKey) keyStore.getKey("key1", null);
 * PublicKey publicKey = keyStore.getCertificate("key1").getPublicKey();
 * }
* *

Example: RSA key pair for signing/verification using RSA-PSS

* This example illustrates how to generate an RSA key pair in the Android KeyStore system under * alias {@code key1} authorized to be used only for signing using the RSA-PSS signature padding * scheme with SHA-256 or SHA-512 digests. The use of public key is unrestricted, thus permitting * signature verification using any padding schemes and digests. *
 {@code
 * KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(
 *         KeyProperties.KEY_ALGORITHM_RSA, "AndroidKeyStore");
 * keyPairGenerator.initialize(
 *         new KeyGenParameterSpec.Builder(
 *                 "key1",
 *                 KeyProperties.PURPOSE_SIGN)
 *                 .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512)
 *                 .setSignaturePaddings(KeyProperties.SIGNATURE_PADDING_RSA_PSS)
 *                 .build());
 * KeyPair keyPair = keyPairGenerator.generateKeyPair();
 * Signature signature = Signature.getInstance("SHA256withRSA/PSS");
 * signature.initSign(keyPair.getPrivate());
 * ...
 *
 * // The key pair can also be obtained from the Android Keystore any time as follows:
 * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
 * keyStore.load(null);
 * PrivateKey privateKey = (PrivateKey) keyStore.getKey("key1", null);
 * PublicKey publicKey = keyStore.getCertificate("key1").getPublicKey();
 * }
* *

Example: RSA key pair for encryption/decryption using RSA OAEP

* This example illustrates how to generate an RSA key pair in the Android KeyStore system under * alias {@code key1} where the private key is authorized to be used only for decryption using RSA * OAEP encryption padding scheme with SHA-256 or SHA-512 digests. The use of public key is * unrestricted, thus permitting encryption using any padding schemes and digests. *
 {@code
 * KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(
 *         KeyProperties.KEY_ALGORITHM_RSA, "AndroidKeyStore");
 * keyPairGenerator.initialize(
 *         new KeyGenParameterSpec.Builder(
 *                 "key1",
 *                 KeyProperties.PURPOSE_DECRYPT)
 *                 .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512)
 *                 .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_RSA_OAEP)
 *                 .build());
 * KeyPair keyPair = keyPairGenerator.generateKeyPair();
 * Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
 * cipher.init(Cipher.DECRYPT_MODE, keyPair.getPrivate());
 * ...
 *
 * // The key pair can also be obtained from the Android Keystore any time as follows:
 * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
 * keyStore.load(null);
 * PrivateKey privateKey = (PrivateKey) keyStore.getKey("key1", null);
 * PublicKey publicKey = keyStore.getCertificate("key1").getPublicKey();
 * }
* *

Example: AES key for encryption/decryption in GCM mode

* The following example illustrates how to generate an AES key in the Android KeyStore system under * alias {@code key2} authorized to be used only for encryption/decryption in GCM mode with no * padding. *
 {@code
 * KeyGenerator keyGenerator = KeyGenerator.getInstance(
 *         KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
 * keyGenerator.initialize(
 *         new KeyGenParameterSpec.Builder("key2",
 *                 KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
 *                 .setBlockModes(KeyProperties.BLOCK_MODE_GCM)
 *                 .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
 *                 .build());
 * SecretKey key = keyGenerator.generateKey();
 *
 * Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 * cipher.init(Cipher.ENCRYPT_MODE, key);
 * ...
 *
 * // The key can also be obtained from the Android Keystore any time as follows:
 * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
 * keyStore.load(null);
 * key = (SecretKey) keyStore.getKey("key2", null);
 * }
* *

Example: HMAC key for generating a MAC using SHA-256

* This example illustrates how to generate an HMAC key in the Android KeyStore system under alias * {@code key2} authorized to be used only for generating an HMAC using SHA-256. *
 {@code
 * KeyGenerator keyGenerator = KeyGenerator.getInstance(
 *         KeyProperties.KEY_ALGORITHM_HMAC_SHA256, "AndroidKeyStore");
 * keyGenerator.initialize(
 *         new KeyGenParameterSpec.Builder("key2", KeyProperties.PURPOSE_SIGN).build());
 * SecretKey key = keyGenerator.generateKey();
 * Mac mac = Mac.getInstance("HmacSHA256");
 * mac.init(key);
 * ...
 *
 * // The key can also be obtained from the Android Keystore any time as follows:
 * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
 * keyStore.load(null);
 * key = (SecretKey) keyStore.getKey("key2", null);
 * }
*/ public final class KeyGenParameterSpec implements AlgorithmParameterSpec { private static final X500Principal DEFAULT_CERT_SUBJECT = new X500Principal("CN=fake"); private static final BigInteger DEFAULT_CERT_SERIAL_NUMBER = new BigInteger("1"); private static final Date DEFAULT_CERT_NOT_BEFORE = new Date(0L); // Jan 1 1970 private static final Date DEFAULT_CERT_NOT_AFTER = new Date(2461449600000L); // Jan 1 2048 private final String mKeystoreAlias; private final int mKeySize; private final AlgorithmParameterSpec mSpec; private final X500Principal mCertificateSubject; private final BigInteger mCertificateSerialNumber; private final Date mCertificateNotBefore; private final Date mCertificateNotAfter; private final Date mKeyValidityStart; private final Date mKeyValidityForOriginationEnd; private final Date mKeyValidityForConsumptionEnd; private final @KeyProperties.PurposeEnum int mPurposes; private final @KeyProperties.DigestEnum String[] mDigests; private final @KeyProperties.EncryptionPaddingEnum String[] mEncryptionPaddings; private final @KeyProperties.SignaturePaddingEnum String[] mSignaturePaddings; private final @KeyProperties.BlockModeEnum String[] mBlockModes; private final boolean mRandomizedEncryptionRequired; private final boolean mUserAuthenticationRequired; private final int mUserAuthenticationValidityDurationSeconds; /** * @hide should be built with Builder */ public KeyGenParameterSpec( String keyStoreAlias, int keySize, AlgorithmParameterSpec spec, X500Principal certificateSubject, BigInteger certificateSerialNumber, Date certificateNotBefore, Date certificateNotAfter, Date keyValidityStart, Date keyValidityForOriginationEnd, Date keyValidityForConsumptionEnd, @KeyProperties.PurposeEnum int purposes, @KeyProperties.DigestEnum String[] digests, @KeyProperties.EncryptionPaddingEnum String[] encryptionPaddings, @KeyProperties.SignaturePaddingEnum String[] signaturePaddings, @KeyProperties.BlockModeEnum String[] blockModes, boolean randomizedEncryptionRequired, boolean userAuthenticationRequired, int userAuthenticationValidityDurationSeconds) { if (TextUtils.isEmpty(keyStoreAlias)) { throw new IllegalArgumentException("keyStoreAlias must not be empty"); } if (certificateSubject == null) { certificateSubject = DEFAULT_CERT_SUBJECT; } if (certificateNotBefore == null) { certificateNotBefore = DEFAULT_CERT_NOT_BEFORE; } if (certificateNotAfter == null) { certificateNotAfter = DEFAULT_CERT_NOT_AFTER; } if (certificateSerialNumber == null) { certificateSerialNumber = DEFAULT_CERT_SERIAL_NUMBER; } if (certificateNotAfter.before(certificateNotBefore)) { throw new IllegalArgumentException("certificateNotAfter < certificateNotBefore"); } mKeystoreAlias = keyStoreAlias; mKeySize = keySize; mSpec = spec; mCertificateSubject = certificateSubject; mCertificateSerialNumber = certificateSerialNumber; mCertificateNotBefore = Utils.cloneIfNotNull(certificateNotBefore); mCertificateNotAfter = Utils.cloneIfNotNull(certificateNotAfter); mKeyValidityStart = Utils.cloneIfNotNull(keyValidityStart); mKeyValidityForOriginationEnd = Utils.cloneIfNotNull(keyValidityForOriginationEnd); mKeyValidityForConsumptionEnd = Utils.cloneIfNotNull(keyValidityForConsumptionEnd); mPurposes = purposes; mDigests = ArrayUtils.cloneIfNotEmpty(digests); mEncryptionPaddings = ArrayUtils.cloneIfNotEmpty(ArrayUtils.nullToEmpty(encryptionPaddings)); mSignaturePaddings = ArrayUtils.cloneIfNotEmpty(ArrayUtils.nullToEmpty(signaturePaddings)); mBlockModes = ArrayUtils.cloneIfNotEmpty(ArrayUtils.nullToEmpty(blockModes)); mRandomizedEncryptionRequired = randomizedEncryptionRequired; mUserAuthenticationRequired = userAuthenticationRequired; mUserAuthenticationValidityDurationSeconds = userAuthenticationValidityDurationSeconds; } /** * Returns the alias that will be used in the {@code java.security.KeyStore} * in conjunction with the {@code AndroidKeyStore}. */ @NonNull public String getKeystoreAlias() { return mKeystoreAlias; } /** * Returns the requested key size. If {@code -1}, the size should be looked up from * {@link #getAlgorithmParameterSpec()}, if provided, otherwise an algorithm-specific default * size should be used. */ public int getKeySize() { return mKeySize; } /** * Returns the key algorithm-specific {@link AlgorithmParameterSpec} that will be used for * creation of the key or {@code null} if algorithm-specific defaults should be used. */ @Nullable public AlgorithmParameterSpec getAlgorithmParameterSpec() { return mSpec; } /** * Returns the subject distinguished name to be used on the X.509 certificate that will be put * in the {@link java.security.KeyStore}. */ @NonNull public X500Principal getCertificateSubject() { return mCertificateSubject; } /** * Returns the serial number to be used on the X.509 certificate that will be put in the * {@link java.security.KeyStore}. */ @NonNull public BigInteger getCertificateSerialNumber() { return mCertificateSerialNumber; } /** * Returns the start date to be used on the X.509 certificate that will be put in the * {@link java.security.KeyStore}. */ @NonNull public Date getCertificateNotBefore() { return Utils.cloneIfNotNull(mCertificateNotBefore); } /** * Returns the end date to be used on the X.509 certificate that will be put in the * {@link java.security.KeyStore}. */ @NonNull public Date getCertificateNotAfter() { return Utils.cloneIfNotNull(mCertificateNotAfter); } /** * Returns the time instant before which the key is not yet valid or {@code null} if not * restricted. */ @Nullable public Date getKeyValidityStart() { return Utils.cloneIfNotNull(mKeyValidityStart); } /** * Returns the time instant after which the key is no longer valid for decryption and * verification or {@code null} if not restricted. */ @Nullable public Date getKeyValidityForConsumptionEnd() { return Utils.cloneIfNotNull(mKeyValidityForConsumptionEnd); } /** * Returns the time instant after which the key is no longer valid for encryption and signing * or {@code null} if not restricted. */ @Nullable public Date getKeyValidityForOriginationEnd() { return Utils.cloneIfNotNull(mKeyValidityForOriginationEnd); } /** * Returns the set of purposes (e.g., encrypt, decrypt, sign) for which the key can be used. * Attempts to use the key for any other purpose will be rejected. * *

See {@link KeyProperties}.{@code PURPOSE} flags. */ public @KeyProperties.PurposeEnum int getPurposes() { return mPurposes; } /** * Returns the set of digest algorithms (e.g., {@code SHA-256}, {@code SHA-384} with which the * key can be used or {@code null} if not specified. * *

See {@link KeyProperties}.{@code DIGEST} constants. * * @throws IllegalStateException if this set has not been specified. * * @see #isDigestsSpecified() */ @NonNull public @KeyProperties.DigestEnum String[] getDigests() { if (mDigests == null) { throw new IllegalStateException("Digests not specified"); } return ArrayUtils.cloneIfNotEmpty(mDigests); } /** * Returns {@code true} if the set of digest algorithms with which the key can be used has been * specified. * * @see #getDigests() */ @NonNull public boolean isDigestsSpecified() { return mDigests != null; } /** * Returns the set of padding schemes (e.g., {@code PKCS7Padding}, {@code OEAPPadding}, * {@code PKCS1Padding}, {@code NoPadding}) with which the key can be used when * encrypting/decrypting. Attempts to use the key with any other padding scheme will be * rejected. * *

See {@link KeyProperties}.{@code ENCRYPTION_PADDING} constants. */ @NonNull public @KeyProperties.EncryptionPaddingEnum String[] getEncryptionPaddings() { return ArrayUtils.cloneIfNotEmpty(mEncryptionPaddings); } /** * Gets the set of padding schemes (e.g., {@code PSS}, {@code PKCS#1}) with which the key * can be used when signing/verifying. Attempts to use the key with any other padding scheme * will be rejected. * *

See {@link KeyProperties}.{@code SIGNATURE_PADDING} constants. */ @NonNull public @KeyProperties.SignaturePaddingEnum String[] getSignaturePaddings() { return ArrayUtils.cloneIfNotEmpty(mSignaturePaddings); } /** * Gets the set of block modes (e.g., {@code GCM}, {@code CBC}) with which the key can be used * when encrypting/decrypting. Attempts to use the key with any other block modes will be * rejected. * *

See {@link KeyProperties}.{@code BLOCK_MODE} constants. */ @NonNull public @KeyProperties.BlockModeEnum String[] getBlockModes() { return ArrayUtils.cloneIfNotEmpty(mBlockModes); } /** * Returns {@code true} if encryption using this key must be sufficiently randomized to produce * different ciphertexts for the same plaintext every time. The formal cryptographic property * being required is indistinguishability under chosen-plaintext attack ({@code * IND-CPA}). This property is important because it mitigates several classes of * weaknesses due to which ciphertext may leak information about plaintext. For example, if a * given plaintext always produces the same ciphertext, an attacker may see the repeated * ciphertexts and be able to deduce something about the plaintext. */ public boolean isRandomizedEncryptionRequired() { return mRandomizedEncryptionRequired; } /** * Returns {@code true} if the key is authorized to be used only if the user has been * authenticated. * *

This authorization applies only to secret key and private key operations. Public key * operations are not restricted. * * @see #getUserAuthenticationValidityDurationSeconds() * @see Builder#setUserAuthenticationRequired(boolean) */ public boolean isUserAuthenticationRequired() { return mUserAuthenticationRequired; } /** * Gets the duration of time (seconds) for which this key is authorized to be used after the * user is successfully authenticated. This has effect only if user authentication is required * (see {@link #isUserAuthenticationRequired()}). * *

This authorization applies only to secret key and private key operations. Public key * operations are not restricted. * * @return duration in seconds or {@code -1} if authentication is required for every use of the * key. * * @see #isUserAuthenticationRequired() * @see Builder#setUserAuthenticationValidityDurationSeconds(int) */ public int getUserAuthenticationValidityDurationSeconds() { return mUserAuthenticationValidityDurationSeconds; } /** * Builder of {@link KeyGenParameterSpec} instances. */ public final static class Builder { private final String mKeystoreAlias; private @KeyProperties.PurposeEnum int mPurposes; private int mKeySize = -1; private AlgorithmParameterSpec mSpec; private X500Principal mCertificateSubject; private BigInteger mCertificateSerialNumber; private Date mCertificateNotBefore; private Date mCertificateNotAfter; private Date mKeyValidityStart; private Date mKeyValidityForOriginationEnd; private Date mKeyValidityForConsumptionEnd; private @KeyProperties.DigestEnum String[] mDigests; private @KeyProperties.EncryptionPaddingEnum String[] mEncryptionPaddings; private @KeyProperties.SignaturePaddingEnum String[] mSignaturePaddings; private @KeyProperties.BlockModeEnum String[] mBlockModes; private boolean mRandomizedEncryptionRequired = true; private boolean mUserAuthenticationRequired; private int mUserAuthenticationValidityDurationSeconds = -1; /** * Creates a new instance of the {@code Builder}. * * @param keystoreAlias alias of the entry in which the generated key will appear in * Android KeyStore. Must not be empty. * @param purposes set of purposes (e.g., encrypt, decrypt, sign) for which the key can be * used. Attempts to use the key for any other purpose will be rejected. * *

If the set of purposes for which the key can be used does not contain * {@link KeyProperties#PURPOSE_SIGN}, the self-signed certificate generated by * {@link KeyPairGenerator} of {@code AndroidKeyStore} provider will contain an * invalid signature. This is OK if the certificate is only used for obtaining the * public key from Android KeyStore. * *

See {@link KeyProperties}.{@code PURPOSE} flags. */ public Builder(@NonNull String keystoreAlias, @KeyProperties.PurposeEnum int purposes) { if (keystoreAlias == null) { throw new NullPointerException("keystoreAlias == null"); } else if (keystoreAlias.isEmpty()) { throw new IllegalArgumentException("keystoreAlias must not be empty"); } mKeystoreAlias = keystoreAlias; mPurposes = purposes; } /** * Sets the size (in bits) of the key to be generated. For instance, for RSA keys this sets * the modulus size, for EC keys this selects a curve with a matching field size, and for * symmetric keys this sets the size of the bitstring which is their key material. * *

The default key size is specific to each key algorithm. If key size is not set * via this method, it should be looked up from the algorithm-specific parameters (if any) * provided via * {@link #setAlgorithmParameterSpec(AlgorithmParameterSpec) setAlgorithmParameterSpec}. */ @NonNull public Builder setKeySize(int keySize) { if (keySize < 0) { throw new IllegalArgumentException("keySize < 0"); } mKeySize = keySize; return this; } /** * Sets the algorithm-specific key generation parameters. For example, for RSA keys this may * be an instance of {@link java.security.spec.RSAKeyGenParameterSpec} whereas for EC keys * this may be an instance of {@link java.security.spec.ECGenParameterSpec}. * *

These key generation parameters must match other explicitly set parameters (if any), * such as key size. */ public Builder setAlgorithmParameterSpec(@NonNull AlgorithmParameterSpec spec) { if (spec == null) { throw new NullPointerException("spec == null"); } mSpec = spec; return this; } /** * Sets the subject used for the self-signed certificate of the generated key pair. * *

By default, the subject is {@code CN=fake}. */ @NonNull public Builder setCertificateSubject(@NonNull X500Principal subject) { if (subject == null) { throw new NullPointerException("subject == null"); } mCertificateSubject = subject; return this; } /** * Sets the serial number used for the self-signed certificate of the generated key pair. * *

By default, the serial number is {@code 1}. */ @NonNull public Builder setCertificateSerialNumber(@NonNull BigInteger serialNumber) { if (serialNumber == null) { throw new NullPointerException("serialNumber == null"); } mCertificateSerialNumber = serialNumber; return this; } /** * Sets the start of the validity period for the self-signed certificate of the generated * key pair. * *

By default, this date is {@code Jan 1 1970}. */ @NonNull public Builder setCertificateNotBefore(@NonNull Date date) { if (date == null) { throw new NullPointerException("date == null"); } mCertificateNotBefore = Utils.cloneIfNotNull(date); return this; } /** * Sets the end of the validity period for the self-signed certificate of the generated key * pair. * *

By default, this date is {@code Jan 1 2048}. */ @NonNull public Builder setCertificateNotAfter(@NonNull Date date) { if (date == null) { throw new NullPointerException("date == null"); } mCertificateNotAfter = Utils.cloneIfNotNull(date); return this; } /** * Sets the time instant before which the key is not yet valid. * *

By default, the key is valid at any instant. * * @see #setKeyValidityEnd(Date) */ @NonNull public Builder setKeyValidityStart(Date startDate) { mKeyValidityStart = Utils.cloneIfNotNull(startDate); return this; } /** * Sets the time instant after which the key is no longer valid. * *

By default, the key is valid at any instant. * * @see #setKeyValidityStart(Date) * @see #setKeyValidityForConsumptionEnd(Date) * @see #setKeyValidityForOriginationEnd(Date) */ @NonNull public Builder setKeyValidityEnd(Date endDate) { setKeyValidityForOriginationEnd(endDate); setKeyValidityForConsumptionEnd(endDate); return this; } /** * Sets the time instant after which the key is no longer valid for encryption and signing. * *

By default, the key is valid at any instant. * * @see #setKeyValidityForConsumptionEnd(Date) */ @NonNull public Builder setKeyValidityForOriginationEnd(Date endDate) { mKeyValidityForOriginationEnd = Utils.cloneIfNotNull(endDate); return this; } /** * Sets the time instant after which the key is no longer valid for decryption and * verification. * *

By default, the key is valid at any instant. * * @see #setKeyValidityForOriginationEnd(Date) */ @NonNull public Builder setKeyValidityForConsumptionEnd(Date endDate) { mKeyValidityForConsumptionEnd = Utils.cloneIfNotNull(endDate); return this; } /** * Sets the set of digests algorithms (e.g., {@code SHA-256}, {@code SHA-384}) with which * the key can be used. Attempts to use the key with any other digest algorithm will be * rejected. * *

This must be specified for signing/verification keys and RSA encryption/decryption * keys used with RSA OAEP padding scheme because these operations involve a digest. For * HMAC keys, the default is the digest associated with the key algorithm (e.g., * {@code SHA-256} for key algorithm {@code HmacSHA256}). HMAC keys cannot be authorized * for more than one digest. * *

For private keys used for TLS/SSL client or server authentication it is usually * necessary to authorize the use of no digest ({@link KeyProperties#DIGEST_NONE}). This is * because TLS/SSL stacks typically generate the necessary digest(s) themselves and then use * a private key to sign it. * *

See {@link KeyProperties}.{@code DIGEST} constants. */ @NonNull public Builder setDigests(@KeyProperties.DigestEnum String... digests) { mDigests = ArrayUtils.cloneIfNotEmpty(digests); return this; } /** * Sets the set of padding schemes (e.g., {@code PKCS7Padding}, {@code OAEPPadding}, * {@code PKCS1Padding}, {@code NoPadding}) with which the key can be used when * encrypting/decrypting. Attempts to use the key with any other padding scheme will be * rejected. * *

This must be specified for keys which are used for encryption/decryption. * *

For RSA private keys used by TLS/SSL servers to authenticate themselves to clients it * is usually necessary to authorize the use of no/any padding * ({@link KeyProperties#ENCRYPTION_PADDING_NONE}) and/or PKCS#1 encryption padding * ({@link KeyProperties#ENCRYPTION_PADDING_RSA_PKCS1}). This is because RSA decryption is * required by some cipher suites, and some stacks request decryption using no padding * whereas others request PKCS#1 padding. * *

See {@link KeyProperties}.{@code ENCRYPTION_PADDING} constants. */ @NonNull public Builder setEncryptionPaddings( @KeyProperties.EncryptionPaddingEnum String... paddings) { mEncryptionPaddings = ArrayUtils.cloneIfNotEmpty(paddings); return this; } /** * Sets the set of padding schemes (e.g., {@code PSS}, {@code PKCS#1}) with which the key * can be used when signing/verifying. Attempts to use the key with any other padding scheme * will be rejected. * *

This must be specified for RSA keys which are used for signing/verification. * *

See {@link KeyProperties}.{@code SIGNATURE_PADDING} constants. */ @NonNull public Builder setSignaturePaddings( @KeyProperties.SignaturePaddingEnum String... paddings) { mSignaturePaddings = ArrayUtils.cloneIfNotEmpty(paddings); return this; } /** * Sets the set of block modes (e.g., {@code GCM}, {@code CBC}) with which the key can be * used when encrypting/decrypting. Attempts to use the key with any other block modes will * be rejected. * *

This must be specified for symmetric encryption/decryption keys. * *

See {@link KeyProperties}.{@code BLOCK_MODE} constants. */ @NonNull public Builder setBlockModes(@KeyProperties.BlockModeEnum String... blockModes) { mBlockModes = ArrayUtils.cloneIfNotEmpty(blockModes); return this; } /** * Sets whether encryption using this key must be sufficiently randomized to produce * different ciphertexts for the same plaintext every time. The formal cryptographic * property being required is indistinguishability under chosen-plaintext attack * ({@code IND-CPA}). This property is important because it mitigates several classes * of weaknesses due to which ciphertext may leak information about plaintext. For example, * if a given plaintext always produces the same ciphertext, an attacker may see the * repeated ciphertexts and be able to deduce something about the plaintext. * *

By default, {@code IND-CPA} is required. * *

When {@code IND-CPA} is required: *

* *

Before disabling this requirement, consider the following approaches instead: *

*/ @NonNull public Builder setRandomizedEncryptionRequired(boolean required) { mRandomizedEncryptionRequired = required; return this; } /** * Sets whether this key is authorized to be used only if the user has been authenticated. * *

By default, the key is authorized to be used regardless of whether the user has been * authenticated. * *

When user authentication is required: *

* *

This authorization applies only to secret key and private key operations. Public key * operations are not restricted. * * @see #setUserAuthenticationValidityDurationSeconds(int) * @see KeyguardManager#isDeviceSecure() * @see FingerprintManager#hasEnrolledFingerprints() */ @NonNull public Builder setUserAuthenticationRequired(boolean required) { mUserAuthenticationRequired = required; return this; } /** * Sets the duration of time (seconds) for which this key is authorized to be used after the * user is successfully authenticated. This has effect if the key requires user * authentication for its use (see {@link #setUserAuthenticationRequired(boolean)}). * *

By default, if user authentication is required, it must take place for every use of * the key. * *

Cryptographic operations involving keys which require user authentication to take * place for every operation can only use fingerprint authentication. This is achieved by * initializing a cryptographic operation ({@link Signature}, {@link Cipher}, {@link Mac}) * with the key, wrapping it into a {@link FingerprintManager.CryptoObject}, invoking * {@code FingerprintManager.authenticate} with {@code CryptoObject}, and proceeding with * the cryptographic operation only if the authentication flow succeeds. * *

Cryptographic operations involving keys which are authorized to be used for a duration * of time after a successful user authentication event can only use secure lock screen * authentication. These cryptographic operations will throw * {@link UserNotAuthenticatedException} during initialization if the user needs to be * authenticated to proceed. This situation can be resolved by the user unlocking the secure * lock screen of the Android or by going through the confirm credential flow initiated by * {@link KeyguardManager#createConfirmDeviceCredentialIntent(CharSequence, CharSequence)}. * Once resolved, initializing a new cryptographic operation using this key (or any other * key which is authorized to be used for a fixed duration of time after user * authentication) should succeed provided the user authentication flow completed * successfully. * * @param seconds duration in seconds or {@code -1} if user authentication must take place * for every use of the key. * * @see #setUserAuthenticationRequired(boolean) * @see FingerprintManager * @see FingerprintManager.CryptoObject * @see KeyguardManager */ @NonNull public Builder setUserAuthenticationValidityDurationSeconds( @IntRange(from = -1) int seconds) { if (seconds < -1) { throw new IllegalArgumentException("seconds must be -1 or larger"); } mUserAuthenticationValidityDurationSeconds = seconds; return this; } /** * Builds an instance of {@code KeyGenParameterSpec}. */ @NonNull public KeyGenParameterSpec build() { return new KeyGenParameterSpec( mKeystoreAlias, mKeySize, mSpec, mCertificateSubject, mCertificateSerialNumber, mCertificateNotBefore, mCertificateNotAfter, mKeyValidityStart, mKeyValidityForOriginationEnd, mKeyValidityForConsumptionEnd, mPurposes, mDigests, mEncryptionPaddings, mSignaturePaddings, mBlockModes, mRandomizedEncryptionRequired, mUserAuthenticationRequired, mUserAuthenticationValidityDurationSeconds); } } }