| /* |
| * 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; |
| |
| import android.os.IBinder; |
| import android.security.keymaster.KeymasterArguments; |
| import android.security.keymaster.KeymasterDefs; |
| import android.security.keymaster.OperationResult; |
| |
| import java.security.AlgorithmParameters; |
| import java.security.InvalidAlgorithmParameterException; |
| import java.security.InvalidKeyException; |
| import java.security.Key; |
| import java.security.NoSuchAlgorithmException; |
| import java.security.SecureRandom; |
| import java.security.spec.AlgorithmParameterSpec; |
| import java.security.spec.InvalidParameterSpecException; |
| import java.util.Arrays; |
| |
| import javax.crypto.AEADBadTagException; |
| import javax.crypto.BadPaddingException; |
| import javax.crypto.Cipher; |
| import javax.crypto.CipherSpi; |
| import javax.crypto.IllegalBlockSizeException; |
| import javax.crypto.NoSuchPaddingException; |
| import javax.crypto.ShortBufferException; |
| import javax.crypto.spec.IvParameterSpec; |
| |
| /** |
| * Base class for {@link CipherSpi} providing Android KeyStore backed ciphers. |
| * |
| * @hide |
| */ |
| public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCryptoOperation { |
| |
| public abstract static class AES extends KeyStoreCipherSpi { |
| protected AES(int keymasterBlockMode, int keymasterPadding, boolean ivUsed) { |
| super(KeymasterDefs.KM_ALGORITHM_AES, |
| keymasterBlockMode, |
| keymasterPadding, |
| 16, |
| ivUsed); |
| } |
| |
| public abstract static class ECB extends AES { |
| protected ECB(int keymasterPadding) { |
| super(KeymasterDefs.KM_MODE_ECB, keymasterPadding, false); |
| } |
| |
| public static class NoPadding extends ECB { |
| public NoPadding() { |
| super(KeymasterDefs.KM_PAD_NONE); |
| } |
| } |
| |
| public static class PKCS7Padding extends ECB { |
| public PKCS7Padding() { |
| super(KeymasterDefs.KM_PAD_PKCS7); |
| } |
| } |
| } |
| |
| public abstract static class CBC extends AES { |
| protected CBC(int keymasterPadding) { |
| super(KeymasterDefs.KM_MODE_CBC, keymasterPadding, true); |
| } |
| |
| public static class NoPadding extends CBC { |
| public NoPadding() { |
| super(KeymasterDefs.KM_PAD_NONE); |
| } |
| } |
| |
| public static class PKCS7Padding extends CBC { |
| public PKCS7Padding() { |
| super(KeymasterDefs.KM_PAD_PKCS7); |
| } |
| } |
| } |
| |
| public abstract static class CTR extends AES { |
| protected CTR(int keymasterPadding) { |
| super(KeymasterDefs.KM_MODE_CTR, keymasterPadding, true); |
| } |
| |
| public static class NoPadding extends CTR { |
| public NoPadding() { |
| super(KeymasterDefs.KM_PAD_NONE); |
| } |
| } |
| } |
| } |
| |
| private final KeyStore mKeyStore; |
| private final int mKeymasterAlgorithm; |
| private final int mKeymasterBlockMode; |
| private final int mKeymasterPadding; |
| private final int mBlockSizeBytes; |
| |
| /** Whether this transformation requires an IV. */ |
| private final boolean mIvRequired; |
| |
| // Fields below are populated by Cipher.init and KeyStore.begin and should be preserved after |
| // doFinal finishes. |
| protected boolean mEncrypting; |
| private KeyStoreSecretKey mKey; |
| private SecureRandom mRng; |
| private boolean mFirstOperationInitiated; |
| private byte[] mIv; |
| /** Whether the current {@code #mIv} has been used by the underlying crypto operation. */ |
| private boolean mIvHasBeenUsed; |
| |
| // Fields below must be reset after doFinal |
| private byte[] mAdditionalEntropyForBegin; |
| |
| /** |
| * Token referencing this operation inside keystore service. It is initialized by |
| * {@code engineInit} and is invalidated when {@code engineDoFinal} succeeds and one some |
| * error conditions in between. |
| */ |
| private IBinder mOperationToken; |
| private Long mOperationHandle; |
| private KeyStoreCryptoOperationChunkedStreamer mMainDataStreamer; |
| |
| protected KeyStoreCipherSpi( |
| int keymasterAlgorithm, |
| int keymasterBlockMode, |
| int keymasterPadding, |
| int blockSizeBytes, |
| boolean ivUsed) { |
| mKeyStore = KeyStore.getInstance(); |
| mKeymasterAlgorithm = keymasterAlgorithm; |
| mKeymasterBlockMode = keymasterBlockMode; |
| mKeymasterPadding = keymasterPadding; |
| mBlockSizeBytes = blockSizeBytes; |
| mIvRequired = ivUsed; |
| } |
| |
| @Override |
| protected void engineInit(int opmode, Key key, SecureRandom random) throws InvalidKeyException { |
| resetAll(); |
| |
| boolean success = false; |
| try { |
| init(opmode, key, random); |
| initAlgorithmSpecificParameters(); |
| ensureKeystoreOperationInitialized(); |
| success = true; |
| } finally { |
| if (!success) { |
| resetAll(); |
| } |
| } |
| } |
| |
| @Override |
| protected void engineInit(int opmode, Key key, AlgorithmParameters params, SecureRandom random) |
| throws InvalidKeyException, InvalidAlgorithmParameterException { |
| resetAll(); |
| |
| boolean success = false; |
| try { |
| init(opmode, key, random); |
| initAlgorithmSpecificParameters(params); |
| ensureKeystoreOperationInitialized(); |
| success = true; |
| } finally { |
| if (!success) { |
| resetAll(); |
| } |
| } |
| } |
| |
| @Override |
| protected void engineInit(int opmode, Key key, AlgorithmParameterSpec params, |
| SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException { |
| resetAll(); |
| |
| boolean success = false; |
| try { |
| init(opmode, key, random); |
| initAlgorithmSpecificParameters(params); |
| ensureKeystoreOperationInitialized(); |
| success = true; |
| } finally { |
| if (!success) { |
| resetAll(); |
| } |
| } |
| } |
| |
| private void init(int opmode, Key key, SecureRandom random) throws InvalidKeyException { |
| if (!(key instanceof KeyStoreSecretKey)) { |
| throw new InvalidKeyException( |
| "Unsupported key: " + ((key != null) ? key.getClass().getName() : "null")); |
| } |
| mKey = (KeyStoreSecretKey) key; |
| mRng = random; |
| mIv = null; |
| mFirstOperationInitiated = false; |
| |
| if ((opmode != Cipher.ENCRYPT_MODE) && (opmode != Cipher.DECRYPT_MODE)) { |
| throw new UnsupportedOperationException( |
| "Only ENCRYPT and DECRYPT modes supported. Mode: " + opmode); |
| } |
| mEncrypting = opmode == Cipher.ENCRYPT_MODE; |
| } |
| |
| private void resetAll() { |
| IBinder operationToken = mOperationToken; |
| if (operationToken != null) { |
| mOperationToken = null; |
| mKeyStore.abort(operationToken); |
| } |
| mEncrypting = false; |
| mKey = null; |
| mRng = null; |
| mFirstOperationInitiated = false; |
| mIv = null; |
| mIvHasBeenUsed = false; |
| mAdditionalEntropyForBegin = null; |
| mOperationToken = null; |
| mOperationHandle = null; |
| mMainDataStreamer = null; |
| } |
| |
| private void resetWhilePreservingInitState() { |
| IBinder operationToken = mOperationToken; |
| if (operationToken != null) { |
| mOperationToken = null; |
| mKeyStore.abort(operationToken); |
| } |
| mOperationHandle = null; |
| mMainDataStreamer = null; |
| mAdditionalEntropyForBegin = null; |
| } |
| |
| private void ensureKeystoreOperationInitialized() { |
| if (mMainDataStreamer != null) { |
| return; |
| } |
| if (mKey == null) { |
| throw new IllegalStateException("Not initialized"); |
| } |
| if ((mEncrypting) && (mIvRequired) && (mIvHasBeenUsed)) { |
| // IV is being reused for encryption: this violates security best practices. |
| throw new IllegalStateException( |
| "IV has already been used. Reusing IV in encryption mode violates security best" |
| + " practices."); |
| } |
| |
| KeymasterArguments keymasterInputArgs = new KeymasterArguments(); |
| keymasterInputArgs.addInt(KeymasterDefs.KM_TAG_ALGORITHM, mKeymasterAlgorithm); |
| keymasterInputArgs.addInt(KeymasterDefs.KM_TAG_BLOCK_MODE, mKeymasterBlockMode); |
| keymasterInputArgs.addInt(KeymasterDefs.KM_TAG_PADDING, mKeymasterPadding); |
| addAlgorithmSpecificParametersToBegin(keymasterInputArgs); |
| |
| KeymasterArguments keymasterOutputArgs = new KeymasterArguments(); |
| OperationResult opResult = mKeyStore.begin( |
| mKey.getAlias(), |
| mEncrypting ? KeymasterDefs.KM_PURPOSE_ENCRYPT : KeymasterDefs.KM_PURPOSE_DECRYPT, |
| true, // permit aborting this operation if keystore runs out of resources |
| keymasterInputArgs, |
| mAdditionalEntropyForBegin, |
| keymasterOutputArgs); |
| mAdditionalEntropyForBegin = null; |
| if (opResult == null) { |
| throw new KeyStoreConnectException(); |
| } else if (opResult.resultCode != KeyStore.NO_ERROR) { |
| throw KeyStore.getCryptoOperationException(opResult.resultCode); |
| } |
| |
| if (opResult.token == null) { |
| throw new CryptoOperationException("Keystore returned null operation token"); |
| } |
| mOperationToken = opResult.token; |
| mOperationHandle = opResult.operationHandle; |
| loadAlgorithmSpecificParametersFromBeginResult(keymasterOutputArgs); |
| mFirstOperationInitiated = true; |
| mIvHasBeenUsed = true; |
| mMainDataStreamer = new KeyStoreCryptoOperationChunkedStreamer( |
| new KeyStoreCryptoOperationChunkedStreamer.MainDataStream( |
| mKeyStore, opResult.token)); |
| } |
| |
| @Override |
| protected byte[] engineUpdate(byte[] input, int inputOffset, int inputLen) { |
| ensureKeystoreOperationInitialized(); |
| |
| if (inputLen == 0) { |
| return null; |
| } |
| |
| byte[] output; |
| try { |
| output = mMainDataStreamer.update(input, inputOffset, inputLen); |
| } catch (KeyStoreException e) { |
| throw KeyStore.getCryptoOperationException(e); |
| } |
| |
| if (output.length == 0) { |
| return null; |
| } |
| |
| return output; |
| } |
| |
| @Override |
| protected int engineUpdate(byte[] input, int inputOffset, int inputLen, byte[] output, |
| int outputOffset) throws ShortBufferException { |
| byte[] outputCopy = engineUpdate(input, inputOffset, inputLen); |
| if (outputCopy == null) { |
| return 0; |
| } |
| int outputAvailable = output.length - outputOffset; |
| if (outputCopy.length > outputAvailable) { |
| throw new ShortBufferException("Output buffer too short. Produced: " |
| + outputCopy.length + ", available: " + outputAvailable); |
| } |
| System.arraycopy(outputCopy, 0, output, outputOffset, outputCopy.length); |
| return outputCopy.length; |
| } |
| |
| @Override |
| protected byte[] engineDoFinal(byte[] input, int inputOffset, int inputLen) |
| throws IllegalBlockSizeException, BadPaddingException { |
| ensureKeystoreOperationInitialized(); |
| |
| byte[] output; |
| try { |
| output = mMainDataStreamer.doFinal(input, inputOffset, inputLen); |
| } catch (KeyStoreException e) { |
| switch (e.getErrorCode()) { |
| case KeymasterDefs.KM_ERROR_INVALID_INPUT_LENGTH: |
| throw new IllegalBlockSizeException(); |
| case KeymasterDefs.KM_ERROR_INVALID_ARGUMENT: |
| throw new BadPaddingException(); |
| case KeymasterDefs.KM_ERROR_VERIFICATION_FAILED: |
| throw new AEADBadTagException(); |
| default: |
| throw KeyStore.getCryptoOperationException(e); |
| } |
| } |
| |
| resetWhilePreservingInitState(); |
| return output; |
| } |
| |
| @Override |
| protected int engineDoFinal(byte[] input, int inputOffset, int inputLen, byte[] output, |
| int outputOffset) throws ShortBufferException, IllegalBlockSizeException, |
| BadPaddingException { |
| byte[] outputCopy = engineDoFinal(input, inputOffset, inputLen); |
| if (outputCopy == null) { |
| return 0; |
| } |
| int outputAvailable = output.length - outputOffset; |
| if (outputCopy.length > outputAvailable) { |
| throw new ShortBufferException("Output buffer too short. Produced: " |
| + outputCopy.length + ", available: " + outputAvailable); |
| } |
| System.arraycopy(outputCopy, 0, output, outputOffset, outputCopy.length); |
| return outputCopy.length; |
| } |
| |
| @Override |
| protected int engineGetBlockSize() { |
| return mBlockSizeBytes; |
| } |
| |
| @Override |
| protected byte[] engineGetIV() { |
| return (mIv != null) ? mIv.clone() : null; |
| } |
| |
| @Override |
| protected int engineGetOutputSize(int inputLen) { |
| return inputLen + 3 * engineGetBlockSize(); |
| } |
| |
| @Override |
| protected void engineSetMode(String mode) throws NoSuchAlgorithmException { |
| // This should never be invoked because all algorithms registered with the AndroidKeyStore |
| // provide explicitly specify block mode. |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| protected void engineSetPadding(String arg0) throws NoSuchPaddingException { |
| // This should never be invoked because all algorithms registered with the AndroidKeyStore |
| // provide explicitly specify padding mode. |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public void finalize() throws Throwable { |
| try { |
| IBinder operationToken = mOperationToken; |
| if (operationToken != null) { |
| mKeyStore.abort(operationToken); |
| } |
| } finally { |
| super.finalize(); |
| } |
| } |
| |
| @Override |
| public Long getOperationHandle() { |
| return mOperationHandle; |
| } |
| |
| // The methods below may need to be overridden by subclasses that use algorithm-specific |
| // parameters. |
| |
| /** |
| * Returns algorithm-specific parameters used by this {@code CipherSpi} instance or {@code null} |
| * if no algorithm-specific parameters are used. |
| * |
| * <p>This implementation only handles the IV parameter. |
| */ |
| @Override |
| protected AlgorithmParameters engineGetParameters() { |
| if (!mIvRequired) { |
| return null; |
| } |
| if ((mIv != null) && (mIv.length > 0)) { |
| try { |
| AlgorithmParameters params = AlgorithmParameters.getInstance("AES"); |
| params.init(new IvParameterSpec(mIv)); |
| return params; |
| } catch (NoSuchAlgorithmException e) { |
| throw new RuntimeException("Failed to obtain AES AlgorithmParameters", e); |
| } catch (InvalidParameterSpecException e) { |
| throw new RuntimeException( |
| "Failed to initialize AES AlgorithmParameters with an IV", e); |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Invoked by {@code engineInit} to initialize algorithm-specific parameters. These parameters |
| * may need to be stored to be reused after {@code doFinal}. |
| * |
| * <p>The default implementation only handles the IV parameters. |
| * |
| * @param params algorithm parameters. |
| * |
| * @throws InvalidAlgorithmParameterException if some/all of the parameters cannot be |
| * automatically configured and thus {@code Cipher.init} needs to be invoked with |
| * explicitly provided parameters. |
| */ |
| protected void initAlgorithmSpecificParameters(AlgorithmParameterSpec params) |
| throws InvalidAlgorithmParameterException { |
| if (!mIvRequired) { |
| if (params != null) { |
| throw new InvalidAlgorithmParameterException("Unsupported parameters: " + params); |
| } |
| return; |
| } |
| |
| // IV is used |
| if (params == null) { |
| if (!mEncrypting) { |
| // IV must be provided by the caller |
| throw new InvalidAlgorithmParameterException( |
| "IvParameterSpec must be provided when decrypting"); |
| } |
| return; |
| } |
| if (!(params instanceof IvParameterSpec)) { |
| throw new InvalidAlgorithmParameterException("Only IvParameterSpec supported"); |
| } |
| mIv = ((IvParameterSpec) params).getIV(); |
| if (mIv == null) { |
| throw new InvalidAlgorithmParameterException("Null IV in IvParameterSpec"); |
| } |
| } |
| |
| /** |
| * Invoked by {@code engineInit} to initialize algorithm-specific parameters. These parameters |
| * may need to be stored to be reused after {@code doFinal}. |
| * |
| * <p>The default implementation only handles the IV parameters. |
| * |
| * @param params algorithm parameters. |
| * |
| * @throws InvalidAlgorithmParameterException if some/all of the parameters cannot be |
| * automatically configured and thus {@code Cipher.init} needs to be invoked with |
| * explicitly provided parameters. |
| */ |
| protected void initAlgorithmSpecificParameters(AlgorithmParameters params) |
| throws InvalidAlgorithmParameterException { |
| if (!mIvRequired) { |
| if (params != null) { |
| throw new InvalidAlgorithmParameterException("Unsupported parameters: " + params); |
| } |
| return; |
| } |
| |
| // IV is used |
| if (params == null) { |
| if (!mEncrypting) { |
| // IV must be provided by the caller |
| throw new InvalidAlgorithmParameterException("IV required when decrypting" |
| + ". Use IvParameterSpec or AlgorithmParameters to provide it."); |
| } |
| return; |
| } |
| |
| IvParameterSpec ivSpec; |
| try { |
| ivSpec = params.getParameterSpec(IvParameterSpec.class); |
| } catch (InvalidParameterSpecException e) { |
| if (!mEncrypting) { |
| // IV must be provided by the caller |
| throw new InvalidAlgorithmParameterException("IV required when decrypting" |
| + ", but not found in parameters: " + params, e); |
| } |
| mIv = null; |
| return; |
| } |
| mIv = ivSpec.getIV(); |
| if (mIv == null) { |
| throw new InvalidAlgorithmParameterException("Null IV in AlgorithmParameters"); |
| } |
| } |
| |
| /** |
| * Invoked by {@code engineInit} to initialize algorithm-specific parameters. These parameters |
| * may need to be stored to be reused after {@code doFinal}. |
| * |
| * <p>The default implementation only handles the IV parameter. |
| * |
| * @throws InvalidKeyException if some/all of the parameters cannot be automatically configured |
| * and thus {@code Cipher.init} needs to be invoked with explicitly provided parameters. |
| */ |
| protected void initAlgorithmSpecificParameters() throws InvalidKeyException { |
| if (!mIvRequired) { |
| return; |
| } |
| |
| // IV is used |
| if (!mEncrypting) { |
| throw new InvalidKeyException("IV required when decrypting" |
| + ". Use IvParameterSpec or AlgorithmParameters to provide it."); |
| } |
| } |
| |
| /** |
| * Invoked to add algorithm-specific parameters for the KeyStore's {@code begin} operation. |
| * |
| * <p>The default implementation takes care of the IV. |
| * |
| * @param keymasterArgs keystore/keymaster arguments to be populated with algorithm-specific |
| * parameters. |
| */ |
| protected void addAlgorithmSpecificParametersToBegin(KeymasterArguments keymasterArgs) { |
| if (!mFirstOperationInitiated) { |
| // First begin operation -- see if we need to provide additional entropy for IV |
| // generation. |
| if (mIvRequired) { |
| // IV is needed |
| if ((mIv == null) && (mEncrypting)) { |
| // IV was not provided by the caller and thus will be generated by keymaster. |
| // Mix in some additional entropy from the provided SecureRandom. |
| if (mRng != null) { |
| mAdditionalEntropyForBegin = new byte[mBlockSizeBytes]; |
| mRng.nextBytes(mAdditionalEntropyForBegin); |
| } |
| } |
| } |
| } |
| |
| if ((mIvRequired) && (mIv != null)) { |
| keymasterArgs.addBlob(KeymasterDefs.KM_TAG_NONCE, mIv); |
| } |
| } |
| |
| /** |
| * Invoked by {@code engineInit} to obtain algorithm-specific parameters from the result of the |
| * Keymaster's {@code begin} operation. Some of these parameters may need to be reused after |
| * {@code doFinal} by {@link #addAlgorithmSpecificParametersToBegin(KeymasterArguments)}. |
| * |
| * <p>The default implementation only takes care of the IV. |
| * |
| * @param keymasterArgs keystore/keymaster arguments returned by KeyStore {@code begin} |
| * operation. |
| */ |
| protected void loadAlgorithmSpecificParametersFromBeginResult( |
| KeymasterArguments keymasterArgs) { |
| // NOTE: Keymaster doesn't always return an IV, even if it's used. |
| byte[] returnedIv = keymasterArgs.getBlob(KeymasterDefs.KM_TAG_NONCE, null); |
| if ((returnedIv != null) && (returnedIv.length == 0)) { |
| returnedIv = null; |
| } |
| |
| if (mIvRequired) { |
| if (mIv == null) { |
| mIv = returnedIv; |
| } else if ((returnedIv != null) && (!Arrays.equals(returnedIv, mIv))) { |
| throw new CryptoOperationException("IV in use differs from provided IV"); |
| } |
| } else { |
| if (returnedIv != null) { |
| throw new CryptoOperationException( |
| "IV in use despite IV not being used by this transformation"); |
| } |
| } |
| } |
| } |