1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.security; 18 19 import com.android.org.bouncycastle.x509.X509V3CertificateGenerator; 20 21 import com.android.org.conscrypt.NativeCrypto; 22 import com.android.org.conscrypt.OpenSSLEngine; 23 24 import java.security.InvalidAlgorithmParameterException; 25 import java.security.InvalidKeyException; 26 import java.security.KeyFactory; 27 import java.security.KeyPair; 28 import java.security.KeyPairGenerator; 29 import java.security.KeyPairGeneratorSpi; 30 import java.security.NoSuchAlgorithmException; 31 import java.security.PrivateKey; 32 import java.security.PublicKey; 33 import java.security.SecureRandom; 34 import java.security.cert.CertificateEncodingException; 35 import java.security.cert.X509Certificate; 36 import java.security.spec.AlgorithmParameterSpec; 37 import java.security.spec.DSAParameterSpec; 38 import java.security.spec.InvalidKeySpecException; 39 import java.security.spec.RSAKeyGenParameterSpec; 40 import java.security.spec.X509EncodedKeySpec; 41 42 /** 43 * Provides a way to create instances of a KeyPair which will be placed in the 44 * Android keystore service usable only by the application that called it. This 45 * can be used in conjunction with 46 * {@link java.security.KeyStore#getInstance(String)} using the 47 * {@code "AndroidKeyStore"} type. 48 * <p> 49 * This class can not be directly instantiated and must instead be used via the 50 * {@link KeyPairGenerator#getInstance(String) 51 * KeyPairGenerator.getInstance("AndroidKeyPairGenerator")} API. 52 * 53 * {@hide} 54 */ 55 public class AndroidKeyPairGenerator extends KeyPairGeneratorSpi { 56 private android.security.KeyStore mKeyStore; 57 58 private KeyPairGeneratorSpec mSpec; 59 60 /** 61 * Generate a KeyPair which is backed by the Android keystore service. You 62 * must call {@link KeyPairGenerator#initialize(AlgorithmParameterSpec)} 63 * with an {@link KeyPairGeneratorSpec} as the {@code params} 64 * argument before calling this otherwise an {@code IllegalStateException} 65 * will be thrown. 66 * <p> 67 * This will create an entry in the Android keystore service with a 68 * self-signed certificate using the {@code params} specified in the 69 * {@code initialize(params)} call. 70 * 71 * @throws IllegalStateException when called before calling 72 * {@link KeyPairGenerator#initialize(AlgorithmParameterSpec)} 73 * @see java.security.KeyPairGeneratorSpi#generateKeyPair() 74 */ 75 @Override 76 public KeyPair generateKeyPair() { 77 if (mKeyStore == null || mSpec == null) { 78 throw new IllegalStateException( 79 "Must call initialize with an android.security.KeyPairGeneratorSpec first"); 80 } 81 82 if (((mSpec.getFlags() & KeyStore.FLAG_ENCRYPTED) != 0) 83 && (mKeyStore.state() != KeyStore.State.UNLOCKED)) { 84 throw new IllegalStateException( 85 "Android keystore must be in initialized and unlocked state " 86 + "if encryption is required"); 87 } 88 89 final String alias = mSpec.getKeystoreAlias(); 90 91 Credentials.deleteAllTypesForAlias(mKeyStore, alias); 92 93 final int keyType = KeyStore.getKeyTypeForAlgorithm(mSpec.getKeyType()); 94 byte[][] args = getArgsForKeyType(keyType, mSpec.getAlgorithmParameterSpec()); 95 96 final String privateKeyAlias = Credentials.USER_PRIVATE_KEY + alias; 97 if (!mKeyStore.generate(privateKeyAlias, KeyStore.UID_SELF, keyType, 98 mSpec.getKeySize(), mSpec.getFlags(), args)) { 99 throw new IllegalStateException("could not generate key in keystore"); 100 } 101 102 final PrivateKey privKey; 103 final OpenSSLEngine engine = OpenSSLEngine.getInstance("keystore"); 104 try { 105 privKey = engine.getPrivateKeyById(privateKeyAlias); 106 } catch (InvalidKeyException e) { 107 throw new RuntimeException("Can't get key", e); 108 } 109 110 final byte[] pubKeyBytes = mKeyStore.getPubkey(privateKeyAlias); 111 112 final PublicKey pubKey; 113 try { 114 final KeyFactory keyFact = KeyFactory.getInstance(mSpec.getKeyType()); 115 pubKey = keyFact.generatePublic(new X509EncodedKeySpec(pubKeyBytes)); 116 } catch (NoSuchAlgorithmException e) { 117 throw new IllegalStateException("Can't instantiate key generator", e); 118 } catch (InvalidKeySpecException e) { 119 throw new IllegalStateException("keystore returned invalid key encoding", e); 120 } 121 122 final X509V3CertificateGenerator certGen = new X509V3CertificateGenerator(); 123 certGen.setPublicKey(pubKey); 124 certGen.setSerialNumber(mSpec.getSerialNumber()); 125 certGen.setSubjectDN(mSpec.getSubjectDN()); 126 certGen.setIssuerDN(mSpec.getSubjectDN()); 127 certGen.setNotBefore(mSpec.getStartDate()); 128 certGen.setNotAfter(mSpec.getEndDate()); 129 certGen.setSignatureAlgorithm(getDefaultSignatureAlgorithmForKeyType(mSpec.getKeyType())); 130 131 final X509Certificate cert; 132 try { 133 cert = certGen.generate(privKey); 134 } catch (Exception e) { 135 Credentials.deleteAllTypesForAlias(mKeyStore, alias); 136 throw new IllegalStateException("Can't generate certificate", e); 137 } 138 139 byte[] certBytes; 140 try { 141 certBytes = cert.getEncoded(); 142 } catch (CertificateEncodingException e) { 143 Credentials.deleteAllTypesForAlias(mKeyStore, alias); 144 throw new IllegalStateException("Can't get encoding of certificate", e); 145 } 146 147 if (!mKeyStore.put(Credentials.USER_CERTIFICATE + alias, certBytes, KeyStore.UID_SELF, 148 mSpec.getFlags())) { 149 Credentials.deleteAllTypesForAlias(mKeyStore, alias); 150 throw new IllegalStateException("Can't store certificate in AndroidKeyStore"); 151 } 152 153 return new KeyPair(pubKey, privKey); 154 } 155 156 private static String getDefaultSignatureAlgorithmForKeyType(String keyType) { 157 if ("RSA".equalsIgnoreCase(keyType)) { 158 return "sha256WithRSA"; 159 } else if ("DSA".equalsIgnoreCase(keyType)) { 160 return "sha1WithDSA"; 161 } else if ("EC".equalsIgnoreCase(keyType)) { 162 return "sha256WithECDSA"; 163 } else { 164 throw new IllegalArgumentException("Unsupported key type " + keyType); 165 } 166 } 167 168 private static byte[][] getArgsForKeyType(int keyType, AlgorithmParameterSpec spec) { 169 switch (keyType) { 170 case NativeCrypto.EVP_PKEY_RSA: 171 if (spec instanceof RSAKeyGenParameterSpec) { 172 RSAKeyGenParameterSpec rsaSpec = (RSAKeyGenParameterSpec) spec; 173 return new byte[][] { rsaSpec.getPublicExponent().toByteArray() }; 174 } 175 break; 176 case NativeCrypto.EVP_PKEY_DSA: 177 if (spec instanceof DSAParameterSpec) { 178 DSAParameterSpec dsaSpec = (DSAParameterSpec) spec; 179 return new byte[][] { dsaSpec.getG().toByteArray(), 180 dsaSpec.getP().toByteArray(), dsaSpec.getQ().toByteArray() }; 181 } 182 break; 183 } 184 return null; 185 } 186 187 @Override 188 public void initialize(int keysize, SecureRandom random) { 189 throw new IllegalArgumentException("cannot specify keysize with AndroidKeyPairGenerator"); 190 } 191 192 @Override 193 public void initialize(AlgorithmParameterSpec params, SecureRandom random) 194 throws InvalidAlgorithmParameterException { 195 if (params == null) { 196 throw new InvalidAlgorithmParameterException( 197 "must supply params of type android.security.KeyPairGeneratorSpec"); 198 } else if (!(params instanceof KeyPairGeneratorSpec)) { 199 throw new InvalidAlgorithmParameterException( 200 "params must be of type android.security.KeyPairGeneratorSpec"); 201 } 202 203 KeyPairGeneratorSpec spec = (KeyPairGeneratorSpec) params; 204 205 mSpec = spec; 206 mKeyStore = android.security.KeyStore.getInstance(); 207 } 208 } 209
