3f8d4d8408
This CL addresses the comments from API Council about Android KeyStore KeyPairGeneratorSpec, KeyGeneratorSpec and KeyStoreParameter: 1. These abstractions should not take or hold references to Context. 2. The Builders of these abstractions should take all mandatory parameters in their constructors rather than expose them as setters -- only optional paratemers should be exposed via setters. These comments cannot be addressed without deprecation in the already launched KeyPairGeneratorSpec and KeyStoreParameter. Instead of deprecating just the getContext methods and Builder constructors, this CL goes for the nuclear option of deprecating KeyPairGeneratorSpec and KeyStoreParameter as a whole and exposing all of the AndroidKeyStore API in the new package android.security.keystore. This enables this CL to correct all of the accrued design issues with KeyPairGeneratorSpec (e.g., naming of certificate-related methods) and KeyStoreParameter. This also makes the transition to API Level M more clear for existing users of the AndroidKeyStore API. These users will only have to deal with the new always-mandatory parameters (e.g., purposes) and sometimes-mandatory (e.g., digests, block modes, paddings) if they switch to the new API. Prior to this CL they would've had to deal with this if they invoked any of the new methods of KeyPairGeneratorSpec or KeyStoreParameter introduced in API Level M. This CL rips out all the new API introduced into KeyPairGeneratorSpec and KeyStoreParameter classes for Android M, thus reverting these classes to the API launched in L MR1. This is because the new API is now in android.security.keystore.KeyGenParameterSpec and KeyProtection respectively. Bug: 21039983 Change-Id: I59672b3c6ef7bc25c40aa85f1c47d9d8a05d627c
395 lines
16 KiB
Java
395 lines
16 KiB
Java
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.security;
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import android.annotation.NonNull;
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import android.security.keystore.KeyGenParameterSpec;
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import android.security.keystore.KeyProperties;
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import com.android.org.bouncycastle.x509.X509V3CertificateGenerator;
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import com.android.org.conscrypt.NativeConstants;
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import com.android.org.conscrypt.OpenSSLEngine;
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import java.security.InvalidAlgorithmParameterException;
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import java.security.InvalidKeyException;
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import java.security.KeyFactory;
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import java.security.KeyPair;
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import java.security.KeyPairGenerator;
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import java.security.KeyPairGeneratorSpi;
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import java.security.NoSuchAlgorithmException;
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import java.security.PrivateKey;
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import java.security.PublicKey;
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import java.security.SecureRandom;
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import java.security.cert.CertificateEncodingException;
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import java.security.cert.X509Certificate;
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import java.security.spec.AlgorithmParameterSpec;
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import java.security.spec.InvalidKeySpecException;
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import java.security.spec.RSAKeyGenParameterSpec;
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import java.security.spec.X509EncodedKeySpec;
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import java.util.Locale;
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/**
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* Provides a way to create instances of a KeyPair which will be placed in the
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* Android keystore service usable only by the application that called it. This
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* can be used in conjunction with
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* {@link java.security.KeyStore#getInstance(String)} using the
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* {@code "AndroidKeyStore"} type.
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* <p>
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* This class can not be directly instantiated and must instead be used via the
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* {@link KeyPairGenerator#getInstance(String)
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* KeyPairGenerator.getInstance("AndroidKeyPairGenerator")} API.
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*
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* {@hide}
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*/
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public abstract class AndroidKeyPairGenerator extends KeyPairGeneratorSpi {
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public static class RSA extends AndroidKeyPairGenerator {
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public RSA() {
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super(KeyProperties.KEY_ALGORITHM_RSA);
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}
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}
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public static class EC extends AndroidKeyPairGenerator {
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public EC() {
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super(KeyProperties.KEY_ALGORITHM_EC);
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}
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}
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/*
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* These must be kept in sync with system/security/keystore/defaults.h
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*/
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/* EC */
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private static final int EC_DEFAULT_KEY_SIZE = 256;
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private static final int EC_MIN_KEY_SIZE = 192;
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private static final int EC_MAX_KEY_SIZE = 521;
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/* RSA */
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private static final int RSA_DEFAULT_KEY_SIZE = 2048;
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private static final int RSA_MIN_KEY_SIZE = 512;
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private static final int RSA_MAX_KEY_SIZE = 8192;
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private final String mAlgorithm;
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private KeyStore mKeyStore;
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private KeyGenParameterSpec mSpec;
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private @KeyProperties.KeyAlgorithmEnum String mKeyAlgorithm;
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private int mKeyType;
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private int mKeySize;
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protected AndroidKeyPairGenerator(@KeyProperties.KeyAlgorithmEnum String algorithm) {
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mAlgorithm = algorithm;
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}
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@KeyProperties.KeyAlgorithmEnum String getAlgorithm() {
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return mAlgorithm;
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}
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/**
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* Generate a KeyPair which is backed by the Android keystore service. You
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* must call {@link KeyPairGenerator#initialize(AlgorithmParameterSpec)}
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* with an {@link KeyPairGeneratorSpec} as the {@code params}
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* argument before calling this otherwise an {@code IllegalStateException}
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* will be thrown.
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* <p>
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* This will create an entry in the Android keystore service with a
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* self-signed certificate using the {@code params} specified in the
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* {@code initialize(params)} call.
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*
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* @throws IllegalStateException when called before calling
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* {@link KeyPairGenerator#initialize(AlgorithmParameterSpec)}
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* @see java.security.KeyPairGeneratorSpi#generateKeyPair()
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*/
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@Override
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public KeyPair generateKeyPair() {
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if (mKeyStore == null || mSpec == null) {
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throw new IllegalStateException("Not initialized");
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}
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final int flags = mSpec.getFlags();
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if (((flags & KeyStore.FLAG_ENCRYPTED) != 0)
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&& (mKeyStore.state() != KeyStore.State.UNLOCKED)) {
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throw new IllegalStateException(
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"Encryption at rest using secure lock screen credential requested for key pair"
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+ ", but the user has not yet entered the credential");
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}
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final String alias = mSpec.getKeystoreAlias();
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Credentials.deleteAllTypesForAlias(mKeyStore, alias);
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byte[][] args = getArgsForKeyType(mKeyType, mSpec.getAlgorithmParameterSpec());
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final String privateKeyAlias = Credentials.USER_PRIVATE_KEY + alias;
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if (!mKeyStore.generate(privateKeyAlias, KeyStore.UID_SELF, mKeyType, mKeySize,
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flags, args)) {
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throw new IllegalStateException("could not generate key in keystore");
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}
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Credentials.deleteSecretKeyTypeForAlias(mKeyStore, alias);
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final PrivateKey privKey;
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final OpenSSLEngine engine = OpenSSLEngine.getInstance("keystore");
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try {
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privKey = engine.getPrivateKeyById(privateKeyAlias);
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} catch (InvalidKeyException e) {
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throw new RuntimeException("Can't get key", e);
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}
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final byte[] pubKeyBytes = mKeyStore.getPubkey(privateKeyAlias);
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final PublicKey pubKey;
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try {
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final KeyFactory keyFact = KeyFactory.getInstance(mKeyAlgorithm);
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pubKey = keyFact.generatePublic(new X509EncodedKeySpec(pubKeyBytes));
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} catch (NoSuchAlgorithmException e) {
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throw new IllegalStateException("Can't instantiate key generator", e);
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} catch (InvalidKeySpecException e) {
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throw new IllegalStateException("keystore returned invalid key encoding", e);
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}
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final X509Certificate cert;
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try {
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cert = generateCertificate(privKey, pubKey);
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} catch (Exception e) {
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Credentials.deleteAllTypesForAlias(mKeyStore, alias);
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throw new IllegalStateException("Can't generate certificate", e);
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}
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byte[] certBytes;
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try {
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certBytes = cert.getEncoded();
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} catch (CertificateEncodingException e) {
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Credentials.deleteAllTypesForAlias(mKeyStore, alias);
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throw new IllegalStateException("Can't get encoding of certificate", e);
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}
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if (!mKeyStore.put(Credentials.USER_CERTIFICATE + alias, certBytes, KeyStore.UID_SELF,
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flags)) {
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Credentials.deleteAllTypesForAlias(mKeyStore, alias);
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throw new IllegalStateException("Can't store certificate in AndroidKeyStore");
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}
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return new KeyPair(pubKey, privKey);
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}
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@SuppressWarnings("deprecation")
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private X509Certificate generateCertificate(PrivateKey privateKey, PublicKey publicKey)
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throws Exception {
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final X509V3CertificateGenerator certGen = new X509V3CertificateGenerator();
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certGen.setPublicKey(publicKey);
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certGen.setSerialNumber(mSpec.getCertificateSerialNumber());
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certGen.setSubjectDN(mSpec.getCertificateSubject());
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certGen.setIssuerDN(mSpec.getCertificateSubject());
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certGen.setNotBefore(mSpec.getCertificateNotBefore());
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certGen.setNotAfter(mSpec.getCertificateNotAfter());
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certGen.setSignatureAlgorithm(getDefaultSignatureAlgorithmForKeyAlgorithm(mKeyAlgorithm));
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return certGen.generate(privateKey);
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}
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@NonNull
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private @KeyProperties.KeyAlgorithmEnum String getKeyAlgorithm(KeyPairGeneratorSpec spec) {
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String result = spec.getKeyType();
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if (result != null) {
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return result;
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}
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return getAlgorithm();
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}
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private static int getDefaultKeySize(int keyType) {
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if (keyType == NativeConstants.EVP_PKEY_EC) {
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return EC_DEFAULT_KEY_SIZE;
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} else if (keyType == NativeConstants.EVP_PKEY_RSA) {
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return RSA_DEFAULT_KEY_SIZE;
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}
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return -1;
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}
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private static void checkValidKeySize(String keyAlgorithm, int keyType, int keySize)
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throws InvalidAlgorithmParameterException {
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if (keyType == NativeConstants.EVP_PKEY_EC) {
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if (keySize < EC_MIN_KEY_SIZE || keySize > EC_MAX_KEY_SIZE) {
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throw new InvalidAlgorithmParameterException("EC keys must be >= "
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+ EC_MIN_KEY_SIZE + " and <= " + EC_MAX_KEY_SIZE);
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}
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} else if (keyType == NativeConstants.EVP_PKEY_RSA) {
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if (keySize < RSA_MIN_KEY_SIZE || keySize > RSA_MAX_KEY_SIZE) {
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throw new InvalidAlgorithmParameterException("RSA keys must be >= "
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+ RSA_MIN_KEY_SIZE + " and <= " + RSA_MAX_KEY_SIZE);
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}
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} else {
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throw new InvalidAlgorithmParameterException(
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"Unsupported key algorithm: " + keyAlgorithm);
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}
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}
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private static void checkCorrectParametersSpec(int keyType, int keySize,
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AlgorithmParameterSpec spec) throws InvalidAlgorithmParameterException {
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if (keyType == NativeConstants.EVP_PKEY_RSA && spec != null) {
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if (spec instanceof RSAKeyGenParameterSpec) {
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RSAKeyGenParameterSpec rsaSpec = (RSAKeyGenParameterSpec) spec;
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if (keySize != -1 && keySize != rsaSpec.getKeysize()) {
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throw new InvalidAlgorithmParameterException("RSA key size must match: "
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+ keySize + " vs " + rsaSpec.getKeysize());
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}
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} else {
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throw new InvalidAlgorithmParameterException(
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"RSA may only use RSAKeyGenParameterSpec");
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}
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}
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}
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private static String getDefaultSignatureAlgorithmForKeyAlgorithm(
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@KeyProperties.KeyAlgorithmEnum String algorithm) {
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if (KeyProperties.KEY_ALGORITHM_RSA.equalsIgnoreCase(algorithm)) {
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return "sha256WithRSA";
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} else if (KeyProperties.KEY_ALGORITHM_EC.equalsIgnoreCase(algorithm)) {
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return "sha256WithECDSA";
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} else {
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throw new IllegalArgumentException("Unsupported key type " + algorithm);
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}
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}
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private static byte[][] getArgsForKeyType(int keyType, AlgorithmParameterSpec spec) {
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switch (keyType) {
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case NativeConstants.EVP_PKEY_RSA:
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if (spec instanceof RSAKeyGenParameterSpec) {
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RSAKeyGenParameterSpec rsaSpec = (RSAKeyGenParameterSpec) spec;
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return new byte[][] { rsaSpec.getPublicExponent().toByteArray() };
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}
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break;
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}
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return null;
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}
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@Override
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public void initialize(int keysize, SecureRandom random) {
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throw new IllegalArgumentException("cannot specify keysize with AndroidKeyPairGenerator");
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}
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@Override
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public void initialize(AlgorithmParameterSpec params, SecureRandom random)
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throws InvalidAlgorithmParameterException {
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if (params == null) {
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throw new InvalidAlgorithmParameterException(
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"Must supply params of type " + KeyGenParameterSpec.class.getName()
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+ " or " + KeyPairGeneratorSpec.class.getName());
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}
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String keyAlgorithm;
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KeyGenParameterSpec spec;
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if (params instanceof KeyPairGeneratorSpec) {
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KeyPairGeneratorSpec legacySpec = (KeyPairGeneratorSpec) params;
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try {
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KeyGenParameterSpec.Builder specBuilder;
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keyAlgorithm = getKeyAlgorithm(legacySpec).toUpperCase(Locale.US);
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if (KeyProperties.KEY_ALGORITHM_EC.equalsIgnoreCase(keyAlgorithm)) {
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specBuilder = new KeyGenParameterSpec.Builder(
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legacySpec.getKeystoreAlias(),
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KeyProperties.PURPOSE_SIGN
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| KeyProperties.PURPOSE_VERIFY);
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specBuilder.setDigests(
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KeyProperties.DIGEST_NONE,
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KeyProperties.DIGEST_MD5,
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KeyProperties.DIGEST_SHA1,
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KeyProperties.DIGEST_SHA224,
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KeyProperties.DIGEST_SHA256,
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KeyProperties.DIGEST_SHA384,
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KeyProperties.DIGEST_SHA512);
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} else if (KeyProperties.KEY_ALGORITHM_RSA.equalsIgnoreCase(keyAlgorithm)) {
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specBuilder = new KeyGenParameterSpec.Builder(
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legacySpec.getKeystoreAlias(),
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KeyProperties.PURPOSE_ENCRYPT
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| KeyProperties.PURPOSE_DECRYPT
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| KeyProperties.PURPOSE_SIGN
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| KeyProperties.PURPOSE_VERIFY);
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specBuilder.setDigests(
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KeyProperties.DIGEST_NONE,
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KeyProperties.DIGEST_MD5,
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KeyProperties.DIGEST_SHA1,
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KeyProperties.DIGEST_SHA224,
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KeyProperties.DIGEST_SHA256,
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KeyProperties.DIGEST_SHA384,
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KeyProperties.DIGEST_SHA512);
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specBuilder.setSignaturePaddings(
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KeyProperties.SIGNATURE_PADDING_RSA_PKCS1);
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specBuilder.setBlockModes(KeyProperties.BLOCK_MODE_ECB);
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specBuilder.setEncryptionPaddings(
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KeyProperties.ENCRYPTION_PADDING_NONE,
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KeyProperties.ENCRYPTION_PADDING_RSA_PKCS1);
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// Disable randomized encryption requirement to support encryption padding NONE
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// above.
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specBuilder.setRandomizedEncryptionRequired(false);
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} else {
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throw new InvalidAlgorithmParameterException(
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"Unsupported key algorithm: " + keyAlgorithm);
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}
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if (legacySpec.getKeySize() != -1) {
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specBuilder.setKeySize(legacySpec.getKeySize());
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}
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if (legacySpec.getAlgorithmParameterSpec() != null) {
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specBuilder.setAlgorithmParameterSpec(legacySpec.getAlgorithmParameterSpec());
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}
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specBuilder.setCertificateSubject(legacySpec.getSubjectDN());
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specBuilder.setCertificateSerialNumber(legacySpec.getSerialNumber());
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specBuilder.setCertificateNotBefore(legacySpec.getStartDate());
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specBuilder.setCertificateNotAfter(legacySpec.getEndDate());
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specBuilder.setEncryptionAtRestRequired(legacySpec.isEncryptionRequired());
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specBuilder.setUserAuthenticationRequired(false);
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spec = specBuilder.build();
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} catch (NullPointerException | IllegalArgumentException e) {
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throw new InvalidAlgorithmParameterException(e);
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}
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} else if (params instanceof KeyGenParameterSpec) {
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spec = (KeyGenParameterSpec) params;
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keyAlgorithm = getAlgorithm();
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} else {
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throw new InvalidAlgorithmParameterException(
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"Unsupported params class: " + params.getClass().getName()
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+ ". Supported: " + KeyGenParameterSpec.class.getName()
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+ ", " + KeyPairGeneratorSpec.class);
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}
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int keyType = KeyStore.getKeyTypeForAlgorithm(keyAlgorithm);
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if (keyType == -1) {
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throw new InvalidAlgorithmParameterException(
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"Unsupported key algorithm: " + keyAlgorithm);
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}
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int keySize = spec.getKeySize();
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if (keySize == -1) {
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keySize = getDefaultKeySize(keyType);
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if (keySize == -1) {
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throw new InvalidAlgorithmParameterException(
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"Unsupported key algorithm: " + keyAlgorithm);
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}
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}
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checkCorrectParametersSpec(keyType, keySize, spec.getAlgorithmParameterSpec());
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checkValidKeySize(keyAlgorithm, keyType, keySize);
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mKeyAlgorithm = keyAlgorithm;
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mKeyType = keyType;
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mKeySize = keySize;
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mSpec = spec;
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mKeyStore = KeyStore.getInstance();
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}
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}
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