| /* |
| * Copyright (C) 2015 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 java.security.Key; |
| import java.security.Signature; |
| import java.security.KeyStore.ProtectionParameter; |
| import java.security.cert.Certificate; |
| import java.util.Date; |
| |
| import javax.crypto.Cipher; |
| import javax.crypto.Mac; |
| |
| /** |
| * Specification of how a key or key pair is secured when imported into the |
| * <a href="{@docRoot}training/articles/keystore.html">Android Keystore system</a>. This class |
| * specifies authorized uses of the imported key, such as whether user authentication is required |
| * for using the key, what operations the key is authorized for (e.g., decryption, but not signing) |
| * with what parameters (e.g., only with a particular padding scheme or digest), and the key's |
| * validity start and end dates. Key use authorizations expressed in this class apply only to secret |
| * keys and private keys -- public keys can be used for any supported operations. |
| * |
| * <p>To import a key or key pair into the Android Keystore, create an instance of this class using |
| * the {@link Builder} and pass the instance into {@link java.security.KeyStore#setEntry(String, java.security.KeyStore.Entry, ProtectionParameter) KeyStore.setEntry} |
| * with the key or key pair being imported. |
| * |
| * <p>To obtain the secret/symmetric 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()}. |
| * |
| * <p>To help obtain algorithm-specific public parameters of key pairs stored in the Android |
| * Keystore, its private keys implement {@link java.security.interfaces.ECKey} or |
| * {@link java.security.interfaces.RSAKey} interfaces whereas its public keys implement |
| * {@link java.security.interfaces.ECPublicKey} or {@link java.security.interfaces.RSAPublicKey} |
| * interfaces. |
| * |
| * <p>NOTE: The key material of keys stored in the Android Keystore is not accessible. |
| * |
| * <p>Instances of this class are immutable. |
| * |
| * <p><h3>Known issues</h3> |
| * A known bug in Android 6.0 (API Level 23) causes user authentication-related authorizations to be |
| * enforced even for public keys. To work around this issue extract the public key material to use |
| * outside of Android Keystore. For example: |
| * <pre> {@code |
| * PublicKey unrestrictedPublicKey = |
| * KeyFactory.getInstance(publicKey.getAlgorithm()).generatePublic( |
| * new X509EncodedKeySpec(publicKey.getEncoded())); |
| * }</pre> |
| * |
| * <p><h3>Example: AES key for encryption/decryption in GCM mode</h3> |
| * This example illustrates how to import an AES key into the Android KeyStore under alias |
| * {@code key1} authorized to be used only for encryption/decryption in GCM mode with no padding. |
| * The key must export its key material via {@link Key#getEncoded()} in {@code RAW} format. |
| * <pre> {@code |
| * SecretKey key = ...; // AES key |
| * |
| * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore"); |
| * keyStore.load(null); |
| * keyStore.setEntry( |
| * "key1", |
| * new KeyStore.SecretKeyEntry(key), |
| * new KeyProtection.Builder(KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT) |
| * .setBlockMode(KeyProperties.BLOCK_MODE_GCM) |
| * .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE) |
| * .build()); |
| * // Key imported, obtain a reference to it. |
| * SecretKey keyStoreKey = (SecretKey) keyStore.getKey("key1", null); |
| * // The original key can now be discarded. |
| * |
| * Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding"); |
| * cipher.init(Cipher.ENCRYPT_MODE, keyStoreKey); |
| * ... |
| * }</pre> |
| * |
| * <p><h3>Example: HMAC key for generating MACs using SHA-512</h3> |
| * This example illustrates how to import an HMAC key into the Android KeyStore under alias |
| * {@code key1} authorized to be used only for generating MACs using SHA-512 digest. The key must |
| * export its key material via {@link Key#getEncoded()} in {@code RAW} format. |
| * <pre> {@code |
| * SecretKey key = ...; // HMAC key of algorithm "HmacSHA512". |
| * |
| * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore"); |
| * keyStore.load(null); |
| * keyStore.setEntry( |
| * "key1", |
| * new KeyStore.SecretKeyEntry(key), |
| * new KeyProtection.Builder(KeyProperties.PURPOSE_SIGN).build()); |
| * // Key imported, obtain a reference to it. |
| * SecretKey keyStoreKey = (SecretKey) keyStore.getKey("key1", null); |
| * // The original key can now be discarded. |
| * |
| * Mac mac = Mac.getInstance("HmacSHA512"); |
| * mac.init(keyStoreKey); |
| * ... |
| * }</pre> |
| * |
| * <p><h3>Example: EC key pair for signing/verification using ECDSA</h3> |
| * This example illustrates how to import an EC key pair into the Android KeyStore under alias |
| * {@code key2} with the private key authorized to be used only for signing with SHA-256 or SHA-512 |
| * digests. The use of the public key is unrestricted. Both the private and the public key must |
| * export their key material via {@link Key#getEncoded()} in {@code PKCS#8} and {@code X.509} format |
| * respectively. |
| * <pre> {@code |
| * PrivateKey privateKey = ...; // EC private key |
| * Certificate[] certChain = ...; // Certificate chain with the first certificate |
| * // containing the corresponding EC public key. |
| * |
| * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore"); |
| * keyStore.load(null); |
| * keyStore.setEntry( |
| * "key2", |
| * new KeyStore.PrivateKeyEntry(privateKey, certChain), |
| * new KeyProtection.Builder(KeyProperties.PURPOSE_SIGN) |
| * .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512) |
| * .build()); |
| * // Key pair imported, obtain a reference to it. |
| * PrivateKey keyStorePrivateKey = (PrivateKey) keyStore.getKey("key2", null); |
| * PublicKey publicKey = keyStore.getCertificate("key2").getPublicKey(); |
| * // The original private key can now be discarded. |
| * |
| * Signature signature = Signature.getInstance("SHA256withECDSA"); |
| * signature.initSign(keyStorePrivateKey); |
| * ... |
| * }</pre> |
| * |
| * <p><h3>Example: RSA key pair for signing/verification using PKCS#1 padding</h3> |
| * This example illustrates how to import an RSA key pair into the Android KeyStore under alias |
| * {@code key2} with the private key authorized to be used only for signing using the PKCS#1 |
| * signature padding scheme with SHA-256 digest and only if the user has been authenticated within |
| * the last ten minutes. The use of the public key is unrestricted (see Known Issues). Both the |
| * private and the public key must export their key material via {@link Key#getEncoded()} in |
| * {@code PKCS#8} and {@code X.509} format respectively. |
| * <pre> {@code |
| * PrivateKey privateKey = ...; // RSA private key |
| * Certificate[] certChain = ...; // Certificate chain with the first certificate |
| * // containing the corresponding RSA public key. |
| * |
| * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore"); |
| * keyStore.load(null); |
| * keyStore.setEntry( |
| * "key2", |
| * new KeyStore.PrivateKeyEntry(privateKey, certChain), |
| * new KeyProtection.Builder(KeyProperties.PURPOSE_SIGN) |
| * .setDigests(KeyProperties.DIGEST_SHA256) |
| * .setSignaturePaddings(KeyProperties.SIGNATURE_PADDING_RSA_PKCS1) |
| * // Only permit this key to be used if the user |
| * // authenticated within the last ten minutes. |
| * .setUserAuthenticationRequired(true) |
| * .setUserAuthenticationValidityDurationSeconds(10 * 60) |
| * .build()); |
| * // Key pair imported, obtain a reference to it. |
| * PrivateKey keyStorePrivateKey = (PrivateKey) keyStore.getKey("key2", null); |
| * PublicKey publicKey = keyStore.getCertificate("key2").getPublicKey(); |
| * // The original private key can now be discarded. |
| * |
| * Signature signature = Signature.getInstance("SHA256withRSA"); |
| * signature.initSign(keyStorePrivateKey); |
| * ... |
| * }</pre> |
| * |
| * <p><h3>Example: RSA key pair for encryption/decryption using PKCS#1 padding</h3> |
| * This example illustrates how to import an RSA key pair into the Android KeyStore under alias |
| * {@code key2} with the private key authorized to be used only for decryption using the PKCS#1 |
| * encryption padding scheme. The use of public key is unrestricted, thus permitting encryption |
| * using any padding schemes and digests. Both the private and the public key must export their key |
| * material via {@link Key#getEncoded()} in {@code PKCS#8} and {@code X.509} format respectively. |
| * <pre> {@code |
| * PrivateKey privateKey = ...; // RSA private key |
| * Certificate[] certChain = ...; // Certificate chain with the first certificate |
| * // containing the corresponding RSA public key. |
| * |
| * KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore"); |
| * keyStore.load(null); |
| * keyStore.setEntry( |
| * "key2", |
| * new KeyStore.PrivateKeyEntry(privateKey, certChain), |
| * new KeyProtection.Builder(KeyProperties.PURPOSE_DECRYPT) |
| * .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_RSA_PKCS1) |
| * .build()); |
| * // Key pair imported, obtain a reference to it. |
| * PrivateKey keyStorePrivateKey = (PrivateKey) keyStore.getKey("key2", null); |
| * PublicKey publicKey = keyStore.getCertificate("key2").getPublicKey(); |
| * // The original private key can now be discarded. |
| * |
| * Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding"); |
| * cipher.init(Cipher.DECRYPT_MODE, keyStorePrivateKey); |
| * ... |
| * }</pre> |
| */ |
| public final class KeyProtection implements ProtectionParameter { |
| private final Date mKeyValidityStart; |
| private final Date mKeyValidityForOriginationEnd; |
| private final Date mKeyValidityForConsumptionEnd; |
| private final @KeyProperties.PurposeEnum int mPurposes; |
| private final @KeyProperties.EncryptionPaddingEnum String[] mEncryptionPaddings; |
| private final @KeyProperties.SignaturePaddingEnum String[] mSignaturePaddings; |
| private final @KeyProperties.DigestEnum String[] mDigests; |
| private final @KeyProperties.BlockModeEnum String[] mBlockModes; |
| private final boolean mRandomizedEncryptionRequired; |
| private final boolean mUserAuthenticationRequired; |
| private final int mUserAuthenticationValidityDurationSeconds; |
| private final boolean mUserAuthenticationValidWhileOnBody; |
| private final boolean mInvalidatedByBiometricEnrollment; |
| |
| private KeyProtection( |
| Date keyValidityStart, |
| Date keyValidityForOriginationEnd, |
| Date keyValidityForConsumptionEnd, |
| @KeyProperties.PurposeEnum int purposes, |
| @KeyProperties.EncryptionPaddingEnum String[] encryptionPaddings, |
| @KeyProperties.SignaturePaddingEnum String[] signaturePaddings, |
| @KeyProperties.DigestEnum String[] digests, |
| @KeyProperties.BlockModeEnum String[] blockModes, |
| boolean randomizedEncryptionRequired, |
| boolean userAuthenticationRequired, |
| int userAuthenticationValidityDurationSeconds, |
| boolean userAuthenticationValidWhileOnBody, |
| boolean invalidatedByBiometricEnrollment) { |
| mKeyValidityStart = Utils.cloneIfNotNull(keyValidityStart); |
| mKeyValidityForOriginationEnd = Utils.cloneIfNotNull(keyValidityForOriginationEnd); |
| mKeyValidityForConsumptionEnd = Utils.cloneIfNotNull(keyValidityForConsumptionEnd); |
| mPurposes = purposes; |
| mEncryptionPaddings = |
| ArrayUtils.cloneIfNotEmpty(ArrayUtils.nullToEmpty(encryptionPaddings)); |
| mSignaturePaddings = |
| ArrayUtils.cloneIfNotEmpty(ArrayUtils.nullToEmpty(signaturePaddings)); |
| mDigests = ArrayUtils.cloneIfNotEmpty(digests); |
| mBlockModes = ArrayUtils.cloneIfNotEmpty(ArrayUtils.nullToEmpty(blockModes)); |
| mRandomizedEncryptionRequired = randomizedEncryptionRequired; |
| mUserAuthenticationRequired = userAuthenticationRequired; |
| mUserAuthenticationValidityDurationSeconds = userAuthenticationValidityDurationSeconds; |
| mUserAuthenticationValidWhileOnBody = userAuthenticationValidWhileOnBody; |
| mInvalidatedByBiometricEnrollment = invalidatedByBiometricEnrollment; |
| } |
| |
| /** |
| * Gets the time instant before which the key is not yet valid. |
| * |
| * @return instant or {@code null} if not restricted. |
| */ |
| @Nullable |
| public Date getKeyValidityStart() { |
| return Utils.cloneIfNotNull(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. |
| */ |
| @Nullable |
| public Date getKeyValidityForConsumptionEnd() { |
| return Utils.cloneIfNotNull(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. |
| */ |
| @Nullable |
| public Date getKeyValidityForOriginationEnd() { |
| return Utils.cloneIfNotNull(mKeyValidityForOriginationEnd); |
| } |
| |
| /** |
| * Gets 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. |
| * |
| * <p>See {@link KeyProperties}.{@code PURPOSE} flags. |
| */ |
| public @KeyProperties.PurposeEnum int getPurposes() { |
| return mPurposes; |
| } |
| |
| /** |
| * Gets the set of padding schemes (e.g., {@code PKCS7Padding}, {@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. |
| * |
| * <p>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. |
| * |
| * <p>See {@link KeyProperties}.{@code SIGNATURE_PADDING} constants. |
| */ |
| @NonNull |
| public @KeyProperties.SignaturePaddingEnum String[] getSignaturePaddings() { |
| return ArrayUtils.cloneIfNotEmpty(mSignaturePaddings); |
| } |
| |
| /** |
| * Gets the set of digest algorithms (e.g., {@code SHA-256}, {@code SHA-384}) with which the key |
| * can be used. |
| * |
| * <p>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() |
| */ |
| public boolean isDigestsSpecified() { |
| return mDigests != null; |
| } |
| |
| /** |
| * 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. |
| * |
| * <p>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 <em>indistinguishability under chosen-plaintext attack ({@code |
| * IND-CPA})</em>. 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. |
| * |
| * <p>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()}). |
| * |
| * <p>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; |
| } |
| |
| /** |
| * Returns {@code true} if the key will be de-authorized when the device is removed from the |
| * user's body. This option has no effect on keys that don't have an authentication validity |
| * duration, and has no effect if the device lacks an on-body sensor. |
| * |
| * <p>Authorization applies only to secret key and private key operations. Public key operations |
| * are not restricted. |
| * |
| * @see #isUserAuthenticationRequired() |
| * @see #getUserAuthenticationValidityDurationSeconds() |
| * @see Builder#setUserAuthenticationValidWhileOnBody(boolean) |
| */ |
| public boolean isUserAuthenticationValidWhileOnBody() { |
| return mUserAuthenticationValidWhileOnBody; |
| } |
| |
| /** |
| * Returns {@code true} if the key is irreversibly invalidated when a new fingerprint is |
| * enrolled or all enrolled fingerprints are removed. This has effect only for keys that |
| * require fingerprint user authentication for every use. |
| * |
| * @see #isUserAuthenticationRequired() |
| * @see #getUserAuthenticationValidityDurationSeconds() |
| * @see Builder#setInvalidatedByBiometricEnrollment(boolean) |
| */ |
| public boolean isInvalidatedByBiometricEnrollment() { |
| return mInvalidatedByBiometricEnrollment; |
| } |
| |
| /** |
| * Builder of {@link KeyProtection} instances. |
| */ |
| public final static class Builder { |
| private @KeyProperties.PurposeEnum int mPurposes; |
| |
| private Date mKeyValidityStart; |
| private Date mKeyValidityForOriginationEnd; |
| private Date mKeyValidityForConsumptionEnd; |
| private @KeyProperties.EncryptionPaddingEnum String[] mEncryptionPaddings; |
| private @KeyProperties.SignaturePaddingEnum String[] mSignaturePaddings; |
| private @KeyProperties.DigestEnum String[] mDigests; |
| private @KeyProperties.BlockModeEnum String[] mBlockModes; |
| private boolean mRandomizedEncryptionRequired = true; |
| private boolean mUserAuthenticationRequired; |
| private int mUserAuthenticationValidityDurationSeconds = -1; |
| private boolean mUserAuthenticationValidWhileOnBody; |
| private boolean mInvalidatedByBiometricEnrollment = true; |
| |
| /** |
| * Creates a new instance of the {@code Builder}. |
| * |
| * @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. |
| * |
| * <p>See {@link KeyProperties}.{@code PURPOSE} flags. |
| */ |
| public Builder(@KeyProperties.PurposeEnum int purposes) { |
| mPurposes = purposes; |
| } |
| |
| /** |
| * Sets the time instant before which the key is not yet valid. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <p>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 padding schemes (e.g., {@code OAEPPadding}, {@code PKCS7Padding}, |
| * {@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. |
| * |
| * <p>This must be specified for keys which are used for encryption/decryption. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <p>This must be specified for RSA keys which are used for signing/verification. |
| * |
| * <p>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 digest 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. |
| * |
| * <p>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 specified in {@link Key#getAlgorithm()} (e.g., |
| * {@code SHA-256} for key algorithm {@code HmacSHA256}). HMAC keys cannot be authorized |
| * for more than one digest. |
| * |
| * <p>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. |
| * |
| * <p>See {@link KeyProperties}.{@code DIGEST} constants. |
| */ |
| @NonNull |
| public Builder setDigests(@KeyProperties.DigestEnum String... digests) { |
| mDigests = ArrayUtils.cloneIfNotEmpty(digests); |
| 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. |
| * |
| * <p>This must be specified for symmetric encryption/decryption keys. |
| * |
| * <p>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 <em>indistinguishability under chosen-plaintext attack |
| * ({@code IND-CPA})</em>. 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. |
| * |
| * <p>By default, {@code IND-CPA} is required. |
| * |
| * <p>When {@code IND-CPA} is required: |
| * <ul> |
| * <li>transformation which do not offer {@code IND-CPA}, such as symmetric ciphers using |
| * {@code ECB} mode or RSA encryption without padding, are prohibited;</li> |
| * <li>in transformations which use an IV, such as symmetric ciphers in {@code GCM}, |
| * {@code CBC}, and {@code CTR} block modes, caller-provided IVs are rejected when |
| * encrypting, to ensure that only random IVs are used.</li> |
| * |
| * <p>Before disabling this requirement, consider the following approaches instead: |
| * <ul> |
| * <li>If you are generating a random IV for encryption and then initializing a {@code} |
| * Cipher using the IV, the solution is to let the {@code Cipher} generate a random IV |
| * instead. This will occur if the {@code Cipher} is initialized for encryption without an |
| * IV. The IV can then be queried via {@link Cipher#getIV()}.</li> |
| * <li>If you are generating a non-random IV (e.g., an IV derived from something not fully |
| * random, such as the name of the file being encrypted, or transaction ID, or password, |
| * or a device identifier), consider changing your design to use a random IV which will then |
| * be provided in addition to the ciphertext to the entities which need to decrypt the |
| * ciphertext.</li> |
| * <li>If you are using RSA encryption without padding, consider switching to padding |
| * schemes which offer {@code IND-CPA}, such as PKCS#1 or OAEP.</li> |
| * </ul> |
| */ |
| @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. |
| * |
| * <p>By default, the key is authorized to be used regardless of whether the user has been |
| * authenticated. |
| * |
| * <p>When user authentication is required: |
| * <ul> |
| * <li>The key can only be import if secure lock screen is set up (see |
| * {@link KeyguardManager#isDeviceSecure()}). Additionally, if the key requires that user |
| * authentication takes place for every use of the key (see |
| * {@link #setUserAuthenticationValidityDurationSeconds(int)}), at least one fingerprint |
| * must be enrolled (see {@link FingerprintManager#hasEnrolledFingerprints()}).</li> |
| * <li>The use of the key must be authorized by the user by authenticating to this Android |
| * device using a subset of their secure lock screen credentials such as |
| * password/PIN/pattern or fingerprint. |
| * <a href="{@docRoot}training/articles/keystore.html#UserAuthentication">More |
| * information</a>. |
| * <li>The key will become <em>irreversibly invalidated</em> once the secure lock screen is |
| * disabled (reconfigured to None, Swipe or other mode which does not authenticate the user) |
| * or when the secure lock screen is forcibly reset (e.g., by a Device Administrator). |
| * Additionally, if the key requires that user authentication takes place for every use of |
| * the key, it is also irreversibly invalidated once a new fingerprint is enrolled or once\ |
| * no more fingerprints are enrolled, unless {@link |
| * #setInvalidatedByBiometricEnrollment(boolean)} is used to allow validity after |
| * enrollment. Attempts to initialize cryptographic operations using such keys will throw |
| * {@link KeyPermanentlyInvalidatedException}.</li> </ul> |
| * |
| * <p>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)}). |
| * |
| * <p>By default, if user authentication is required, it must take place for every use of |
| * the key. |
| * |
| * <p>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. |
| * |
| * <p>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; |
| } |
| |
| /** |
| * Sets whether the key will remain authorized only until the device is removed from the |
| * user's body up to the limit of the authentication validity period (see |
| * {@link #setUserAuthenticationValidityDurationSeconds} and |
| * {@link #setUserAuthenticationRequired}). Once the device has been removed from the |
| * user's body, the key will be considered unauthorized and the user will need to |
| * re-authenticate to use it. For keys without an authentication validity period this |
| * parameter has no effect. |
| * |
| * <p>Similarly, on devices that do not have an on-body sensor, this parameter will have no |
| * effect; the device will always be considered to be "on-body" and the key will therefore |
| * remain authorized until the validity period ends. |
| * |
| * @param remainsValid if {@code true}, and if the device supports on-body detection, key |
| * will be invalidated when the device is removed from the user's body or when the |
| * authentication validity expires, whichever occurs first. |
| */ |
| @NonNull |
| public Builder setUserAuthenticationValidWhileOnBody(boolean remainsValid) { |
| mUserAuthenticationValidWhileOnBody = remainsValid; |
| return this; |
| } |
| |
| /** |
| * Sets whether this key should be invalidated on fingerprint enrollment. This |
| * applies only to keys which require user authentication (see {@link |
| * #setUserAuthenticationRequired(boolean)}) and if no positive validity duration has been |
| * set (see {@link #setUserAuthenticationValidityDurationSeconds(int)}, meaning the key is |
| * valid for fingerprint authentication only. |
| * |
| * <p>By default, {@code invalidateKey} is {@code true}, so keys that are valid for |
| * fingerprint authentication only are <em>irreversibly invalidated</em> when a new |
| * fingerprint is enrolled, or when all existing fingerprints are deleted. That may be |
| * changed by calling this method with {@code invalidateKey} set to {@code false}. |
| * |
| * <p>Invalidating keys on enrollment of a new finger or unenrollment of all fingers |
| * improves security by ensuring that an unauthorized person who obtains the password can't |
| * gain the use of fingerprint-authenticated keys by enrolling their own finger. However, |
| * invalidating keys makes key-dependent operations impossible, requiring some fallback |
| * procedure to authenticate the user and set up a new key. |
| */ |
| @NonNull |
| public Builder setInvalidatedByBiometricEnrollment(boolean invalidateKey) { |
| mInvalidatedByBiometricEnrollment = invalidateKey; |
| return this; |
| } |
| |
| /** |
| * Builds an instance of {@link KeyProtection}. |
| * |
| * @throws IllegalArgumentException if a required field is missing |
| */ |
| @NonNull |
| public KeyProtection build() { |
| return new KeyProtection( |
| mKeyValidityStart, |
| mKeyValidityForOriginationEnd, |
| mKeyValidityForConsumptionEnd, |
| mPurposes, |
| mEncryptionPaddings, |
| mSignaturePaddings, |
| mDigests, |
| mBlockModes, |
| mRandomizedEncryptionRequired, |
| mUserAuthenticationRequired, |
| mUserAuthenticationValidityDurationSeconds, |
| mUserAuthenticationValidWhileOnBody, |
| mInvalidatedByBiometricEnrollment); |
| } |
| } |
| } |
