| // Copyright 2017 Google Inc. |
| // |
| // 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 com.google.crypto.tink.streamingaead; |
| |
| import com.google.crypto.tink.KeyTemplate; |
| import com.google.crypto.tink.KeyTypeManager; |
| import com.google.crypto.tink.Registry; |
| import com.google.crypto.tink.StreamingAead; |
| import com.google.crypto.tink.proto.AesGcmHkdfStreamingKey; |
| import com.google.crypto.tink.proto.AesGcmHkdfStreamingKeyFormat; |
| import com.google.crypto.tink.proto.AesGcmHkdfStreamingParams; |
| import com.google.crypto.tink.proto.HashType; |
| import com.google.crypto.tink.proto.KeyData.KeyMaterialType; |
| import com.google.crypto.tink.subtle.AesGcmHkdfStreaming; |
| import com.google.crypto.tink.subtle.Random; |
| import com.google.crypto.tink.subtle.Validators; |
| import com.google.protobuf.ByteString; |
| import com.google.protobuf.ExtensionRegistryLite; |
| import com.google.protobuf.InvalidProtocolBufferException; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.security.GeneralSecurityException; |
| |
| /** |
| * This key manager generates new {@code AesGcmHkdfStreamingKey} keys and produces new instances of |
| * {@code AesGcmHkdfStreaming}. |
| */ |
| public final class AesGcmHkdfStreamingKeyManager extends KeyTypeManager<AesGcmHkdfStreamingKey> { |
| AesGcmHkdfStreamingKeyManager() { |
| super( |
| AesGcmHkdfStreamingKey.class, |
| new PrimitiveFactory<StreamingAead, AesGcmHkdfStreamingKey>(StreamingAead.class) { |
| @Override |
| public StreamingAead getPrimitive(AesGcmHkdfStreamingKey key) |
| throws GeneralSecurityException { |
| return new AesGcmHkdfStreaming( |
| key.getKeyValue().toByteArray(), |
| StreamingAeadUtil.toHmacAlgo(key.getParams().getHkdfHashType()), |
| key.getParams().getDerivedKeySize(), |
| key.getParams().getCiphertextSegmentSize(), |
| /* firstSegmentOffset= */ 0); |
| } |
| }); |
| } |
| |
| private static final int NONCE_PREFIX_IN_BYTES = 7; |
| private static final int TAG_SIZE_IN_BYTES = 16; |
| |
| @Override |
| public String getKeyType() { |
| return "type.googleapis.com/google.crypto.tink.AesGcmHkdfStreamingKey"; |
| } |
| |
| @Override |
| public int getVersion() { |
| return 0; |
| } |
| |
| @Override |
| public KeyMaterialType keyMaterialType() { |
| return KeyMaterialType.SYMMETRIC; |
| } |
| |
| @Override |
| public void validateKey(AesGcmHkdfStreamingKey key) throws GeneralSecurityException { |
| Validators.validateVersion(key.getVersion(), getVersion()); |
| validateParams(key.getParams()); |
| } |
| |
| @Override |
| public AesGcmHkdfStreamingKey parseKey(ByteString byteString) |
| throws InvalidProtocolBufferException { |
| return AesGcmHkdfStreamingKey.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry()); |
| } |
| |
| @Override |
| public KeyFactory<AesGcmHkdfStreamingKeyFormat, AesGcmHkdfStreamingKey> keyFactory() { |
| return new KeyFactory<AesGcmHkdfStreamingKeyFormat, AesGcmHkdfStreamingKey>( |
| AesGcmHkdfStreamingKeyFormat.class) { |
| @Override |
| public void validateKeyFormat(AesGcmHkdfStreamingKeyFormat format) |
| throws GeneralSecurityException { |
| if (format.getKeySize() < 16) { |
| throw new GeneralSecurityException("key_size must be at least 16 bytes"); |
| } |
| validateParams(format.getParams()); |
| } |
| |
| @Override |
| public AesGcmHkdfStreamingKeyFormat parseKeyFormat(ByteString byteString) |
| throws InvalidProtocolBufferException { |
| return AesGcmHkdfStreamingKeyFormat.parseFrom( |
| byteString, ExtensionRegistryLite.getEmptyRegistry()); |
| } |
| |
| @Override |
| public AesGcmHkdfStreamingKey createKey(AesGcmHkdfStreamingKeyFormat format) |
| throws GeneralSecurityException { |
| return AesGcmHkdfStreamingKey.newBuilder() |
| .setKeyValue(ByteString.copyFrom(Random.randBytes(format.getKeySize()))) |
| .setParams(format.getParams()) |
| .setVersion(getVersion()) |
| .build(); |
| } |
| |
| @Override |
| public AesGcmHkdfStreamingKey deriveKey( |
| AesGcmHkdfStreamingKeyFormat format, InputStream inputStream) |
| throws GeneralSecurityException { |
| Validators.validateVersion(format.getVersion(), getVersion()); |
| byte[] pseudorandomness = new byte[format.getKeySize()]; |
| try { |
| int read = inputStream.read(pseudorandomness); |
| if (read != format.getKeySize()) { |
| throw new GeneralSecurityException("Not enough pseudorandomness given"); |
| } |
| return AesGcmHkdfStreamingKey.newBuilder() |
| .setKeyValue(ByteString.copyFrom(pseudorandomness)) |
| .setParams(format.getParams()) |
| .setVersion(getVersion()) |
| .build(); |
| } catch (IOException e) { |
| throw new GeneralSecurityException("Reading pseudorandomness failed", e); |
| } |
| } |
| }; |
| } |
| |
| private static void validateParams(AesGcmHkdfStreamingParams params) |
| throws GeneralSecurityException { |
| Validators.validateAesKeySize(params.getDerivedKeySize()); |
| if (params.getHkdfHashType() == HashType.UNKNOWN_HASH) { |
| throw new GeneralSecurityException("unknown HKDF hash type"); |
| } |
| if (params.getCiphertextSegmentSize() |
| < params.getDerivedKeySize() + NONCE_PREFIX_IN_BYTES + TAG_SIZE_IN_BYTES + 2) { |
| throw new GeneralSecurityException( |
| "ciphertext_segment_size must be at least (derived_key_size + NONCE_PREFIX_IN_BYTES + " |
| + "TAG_SIZE_IN_BYTES + 2)"); |
| } |
| } |
| |
| public static void register(boolean newKeyAllowed) throws GeneralSecurityException { |
| Registry.registerKeyManager(new AesGcmHkdfStreamingKeyManager(), newKeyAllowed); |
| } |
| |
| /** |
| * @return a {@link KeyTemplate} that generates new instances of AesGcmHkdfStreaming keys with the |
| * following parameters: |
| * <ul> |
| * <li>Size of the main key: 16 bytes |
| * <li>HKDF algo: HMAC-SHA256 |
| * <li>Size of AES-GCM derived keys: 16 bytes |
| * <li>Ciphertext segment size: 4096 bytes |
| * </ul> |
| */ |
| public static final KeyTemplate aes128GcmHkdf4KBTemplate() { |
| return createKeyTemplate(16, HashType.SHA256, 16, 4096); |
| } |
| |
| /** |
| * @return a {@link KeyTemplate} that generates new instances of AesGcmHkdfStreaming keys with the |
| * following parameters: |
| * <ul> |
| * <li>Size of the main key: 16 bytes |
| * <li>HKDF algo: HMAC-SHA256 |
| * <li>Size of AES-GCM derived keys: 16 bytes |
| * <li>Ciphertext segment size: 1MB |
| * </ul> |
| */ |
| public static final KeyTemplate aes128GcmHkdf1MBTemplate() { |
| return createKeyTemplate(16, HashType.SHA256, 16, 1 << 20); |
| } |
| |
| /** |
| * @return a {@link KeyTemplate} that generates new instances of AesGcmHkdfStreaming keys with the |
| * following parameters: |
| * <ul> |
| * <li>Size of the main key: 32 bytes |
| * <li>HKDF algo: HMAC-SHA256 |
| * <li>Size of AES-GCM derived keys: 32 bytes |
| * <li>Ciphertext segment size: 4096 bytes |
| * </ul> |
| */ |
| public static final KeyTemplate aes256GcmHkdf4KBTemplate() { |
| return createKeyTemplate(32, HashType.SHA256, 32, 4096); |
| } |
| |
| /** |
| * @return a {@link KeyTemplate} that generates new instances of AesGcmHkdfStreaming keys with the |
| * following parameters: |
| * <ul> |
| * <li>Size of the main key: 32 bytes |
| * <li>HKDF algo: HMAC-SHA256 |
| * <li>Size of AES-GCM derived keys: 32 bytes |
| * <li>Ciphertext segment size: 1MB |
| * </ul> |
| */ |
| public static final KeyTemplate aes256GcmHkdf1MBTemplate() { |
| return createKeyTemplate(32, HashType.SHA256, 32, 1 << 20); |
| } |
| |
| /** |
| * @return a {@code KeyTemplate} containing a {@code AesGcmHkdfStreamingKeyFormat} with some |
| * specified parameters. |
| */ |
| private static KeyTemplate createKeyTemplate( |
| int mainKeySize, HashType hkdfHashType, int derivedKeySize, int ciphertextSegmentSize) { |
| AesGcmHkdfStreamingParams keyParams = |
| AesGcmHkdfStreamingParams.newBuilder() |
| .setCiphertextSegmentSize(ciphertextSegmentSize) |
| .setDerivedKeySize(derivedKeySize) |
| .setHkdfHashType(hkdfHashType) |
| .build(); |
| AesGcmHkdfStreamingKeyFormat format = |
| AesGcmHkdfStreamingKeyFormat.newBuilder() |
| .setKeySize(mainKeySize) |
| .setParams(keyParams) |
| .build(); |
| return KeyTemplate.create( |
| new AesGcmHkdfStreamingKeyManager().getKeyType(), |
| format.toByteArray(), |
| KeyTemplate.OutputPrefixType.RAW); |
| } |
| } |
