| /* |
| * 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 <a href="{@docRoot}training/articles/keystore.html">Android Keystore |
| * system</a>. The spec determines whether user authentication is required for using the key, what |
| * uses the key is authorized for (e.g., only for signing -- decryption not permitted), the key's |
| * validity start and end dates. |
| * |
| * <p>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 KeyPairGeneratorSpec} instance, and then generate a key or key pair using |
| * {@link KeyPairGenerator#generateKeyPair()}. |
| * |
| * <p>The generated key pair or key will be returned by the generator and also stored in the Android |
| * Keystore system 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 system use |
| * {@link java.security.KeyStore#getCertificate(String)} and then |
| * {@link Certificate#getPublicKey()}. |
| * |
| * <p>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). |
| * |
| * <p>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: |
| * <ul> |
| * <li>{@link KeyProperties#PURPOSE_SIGN},</li> |
| * <li>operation without requiring the user to be authenticated (see |
| * {@link Builder#setUserAuthenticationRequired(boolean)}),</li> |
| * <li>signing/origination at this moment in time (see {@link Builder#setKeyValidityStart(Date)} |
| * and {@link Builder#setKeyValidityForOriginationEnd(Date)}),</li> |
| * <li>suitable digest or {@link KeyProperties#DIGEST_NONE},</li> |
| * <li>(RSA keys only) padding scheme {@link KeyProperties#SIGNATURE_PADDING_RSA_PKCS1} or |
| * {@link KeyProperties#ENCRYPTION_PADDING_NONE}.</li> |
| * </ul> |
| * |
| * <p>NOTE: The key material of the generated symmetric and private keys is not accessible. The key |
| * material of the public keys is accessible. |
| * |
| * <p>Instances of this class are immutable. |
| * |
| * <p><h3>Example: Asymmetric key pair</h3> |
| * The following example illustrates how to generate an EC key pair in the Android KeyStore system |
| * under alias {@code key1} 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. |
| * <pre> {@code |
| * KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance( |
| * KeyProperties.KEY_ALGORITHM_EC, |
| * "AndroidKeyStore"); |
| * keyPairGenerator.initialize( |
| * new KeyGenParameterSpec.Builder( |
| * "key1", |
| * KeyProperties.PURPOSE_SIGN | KeyProperties.PURPOSE_VERIFY) |
| * .setDigests(KeyProperties.DIGEST_SHA256, |
| * KeyProperties.DIGEST_SHA384, |
| * KeyProperties.DIGEST_SHA512) |
| * // Only permit this key to be used if the user authenticated |
| * // within the last five minutes. |
| * .setUserAuthenticationRequired(true) |
| * .setUserAuthenticationValidityDurationSeconds(5 * 60) |
| * .build()); |
| * KeyPair keyPair = keyPairGenerator.generateKeyPair(); |
| * |
| * // 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(); |
| * }</pre> |
| * |
| * <p><h3>Example: Symmetric key</h3> |
| * 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. |
| * <pre> {@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(); |
| * |
| * // 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); |
| * }</pre> |
| */ |
| 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. |
| * |
| * <p>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. |
| * |
| * <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() |
| */ |
| @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. |
| * |
| * <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 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; |
| } |
| |
| /** |
| * 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. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <p>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}. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <p>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. |
| * |
| * <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 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. |
| * |
| * <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 associated with the key algorithm (e.g., |
| * {@code SHA-256} for key algorithm {@code HmacSHA256}). |
| * |
| * <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 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. |
| * |
| * <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}). 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 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>encryption/decryption transformation which do not offer {@code IND-CPA}, such as |
| * {@code ECB} with a symmetric encryption algorithm, or RSA encryption/decryption without |
| * padding, are prohibited;</li> |
| * <li>in block modes which use an IV, such as {@code GCM}, {@code CBC}, and {@code CTR}, |
| * caller-provided IVs are rejected when encrypting, to ensure that only random IVs are |
| * used.</li> |
| * </ul> |
| * |
| * <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 encryption |
| * 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 generated 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. 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; |
| } |
| |
| /** |
| * 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); |
| } |
| } |
| } |
