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// 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.aead;
import com.google.crypto.tink.Aead;
import com.google.crypto.tink.KeyTemplate;
import com.google.crypto.tink.Registry;
import com.google.crypto.tink.config.internal.TinkFipsUtil;
import com.google.crypto.tink.internal.KeyTypeManager;
import com.google.crypto.tink.internal.PrimitiveFactory;
import com.google.crypto.tink.proto.AesGcmKey;
import com.google.crypto.tink.proto.AesGcmKeyFormat;
import com.google.crypto.tink.proto.KeyData.KeyMaterialType;
import com.google.crypto.tink.subtle.AesGcmJce;
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;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* This key manager generates new {@code AesGcmKey} keys and produces new instances of {@code
* AesGcmJce}.
*/
public final class AesGcmKeyManager extends KeyTypeManager<AesGcmKey> {
AesGcmKeyManager() {
super(
AesGcmKey.class,
new PrimitiveFactory<Aead, AesGcmKey>(Aead.class) {
@Override
public Aead getPrimitive(AesGcmKey key) throws GeneralSecurityException {
return new AesGcmJce(key.getKeyValue().toByteArray());
}
});
}
@Override
public String getKeyType() {
return "type.googleapis.com/google.crypto.tink.AesGcmKey";
}
@Override
public int getVersion() {
return 0;
}
@Override
public KeyMaterialType keyMaterialType() {
return KeyMaterialType.SYMMETRIC;
}
@Override
public void validateKey(AesGcmKey key) throws GeneralSecurityException {
Validators.validateVersion(key.getVersion(), getVersion());
Validators.validateAesKeySize(key.getKeyValue().size());
}
@Override
public AesGcmKey parseKey(ByteString byteString) throws InvalidProtocolBufferException {
return AesGcmKey.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry());
}
@Override
public KeyFactory<AesGcmKeyFormat, AesGcmKey> keyFactory() {
return new KeyFactory<AesGcmKeyFormat, AesGcmKey>(AesGcmKeyFormat.class) {
@Override
public void validateKeyFormat(AesGcmKeyFormat format) throws GeneralSecurityException {
Validators.validateAesKeySize(format.getKeySize());
}
@Override
public AesGcmKeyFormat parseKeyFormat(ByteString byteString)
throws InvalidProtocolBufferException {
return AesGcmKeyFormat.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry());
}
@Override
public AesGcmKey createKey(AesGcmKeyFormat format) throws GeneralSecurityException {
return AesGcmKey.newBuilder()
.setKeyValue(ByteString.copyFrom(Random.randBytes(format.getKeySize())))
.setVersion(getVersion())
.build();
}
@Override
public AesGcmKey deriveKey(AesGcmKeyFormat format, InputStream inputStream)
throws GeneralSecurityException {
Validators.validateVersion(format.getVersion(), getVersion());
byte[] pseudorandomness = new byte[format.getKeySize()];
try {
readFully(inputStream, pseudorandomness);
return AesGcmKey.newBuilder()
.setKeyValue(ByteString.copyFrom(pseudorandomness))
.setVersion(getVersion())
.build();
} catch (IOException e) {
throw new GeneralSecurityException("Reading pseudorandomness failed", e);
}
}
@Override
public Map<String, KeyFactory.KeyFormat<AesGcmKeyFormat>> keyFormats()
throws GeneralSecurityException {
Map<String, KeyFactory.KeyFormat<AesGcmKeyFormat>> result = new HashMap<>();
result.put("AES128_GCM", createKeyFormat(16, KeyTemplate.OutputPrefixType.TINK));
result.put("AES128_GCM_RAW", createKeyFormat(16, KeyTemplate.OutputPrefixType.RAW));
result.put("AES256_GCM", createKeyFormat(32, KeyTemplate.OutputPrefixType.TINK));
result.put("AES256_GCM_RAW", createKeyFormat(32, KeyTemplate.OutputPrefixType.RAW));
return Collections.unmodifiableMap(result);
}
};
}
public static void register(boolean newKeyAllowed) throws GeneralSecurityException {
Registry.registerKeyManager(new AesGcmKeyManager(), newKeyAllowed);
AesGcmProtoSerialization.register();
}
/**
* @return a {@link KeyTemplate} that generates new instances of AES-GCM with the following
* parameters:
* <ul>
* <li>Key size: 16 bytes
* <li>Prefix type: {@link KeyTemplate.OutputPrefixType#TINK}
* </ul>
* <p>On Android KitKat (API level 19), the {@link com.google.crypto.tink.Aead} instance
* generated by this key template does not support associated data. It might not work at all
* in older versions.
*/
public static final KeyTemplate aes128GcmTemplate() {
return createKeyTemplate(16, KeyTemplate.OutputPrefixType.TINK);
}
/**
* @return a {@link KeyTemplate} that generates new instances of AES-GCM with the following
* parameters:
* <ul>
* <li>Key size: 16 bytes
* <li>Prefix type: {@link KeyTemplate.OutputPrefixType#RAW} (no prefix)
* </ul>
* <p>Keys generated from this template should create ciphertexts compatible with other
* libraries.
* <p>On Android KitKat (API level 19), the {@link com.google.crypto.tink.Aead} instance
* generated by this key template does not support associated data. It might not work at all
* in older versions.
*/
public static final KeyTemplate rawAes128GcmTemplate() {
return createKeyTemplate(16, KeyTemplate.OutputPrefixType.RAW);
}
/**
* @return a {@link KeyTemplate} that generates new instances of AES-GCM with the following
* parameters:
* <ul>
* <li>Key size: 32 bytes
* <li>Prefix type: {@link KeyTemplate.OutputPrefixType#TINK}
* </ul>
* <p>On Android KitKat (API level 19), the {@link com.google.crypto.tink.Aead} instance
* generated by this key template does not support associated data. It might not work at all
* in older versions.
*/
public static final KeyTemplate aes256GcmTemplate() {
return createKeyTemplate(32, KeyTemplate.OutputPrefixType.TINK);
}
/**
* @return a {@link KeyTemplate} that generates new instances of AES-GCM with the following
* parameters:
* <ul>
* <li>Key size: 32 bytes
* <li>Prefix type: {@link KeyTemplate.OutputPrefixType#RAW} (no prefix)
* </ul>
* <p>Keys generated from this template should create ciphertexts compatible with other
* libraries.
* <p>On Android KitKat (API level 19), the {@link com.google.crypto.tink.Aead} instance
* generated by this key template does not support associated data. It might not work at all
* in older versions.
*/
public static final KeyTemplate rawAes256GcmTemplate() {
return createKeyTemplate(32, KeyTemplate.OutputPrefixType.RAW);
}
/**
* @return a {@link KeyTemplate} containing a {@link AesGcmKeyFormat} with some specified
* parameters.
*/
private static KeyTemplate createKeyTemplate(
int keySize, KeyTemplate.OutputPrefixType prefixType) {
AesGcmKeyFormat format = AesGcmKeyFormat.newBuilder().setKeySize(keySize).build();
return KeyTemplate.create(
new AesGcmKeyManager().getKeyType(), format.toByteArray(), prefixType);
}
private static KeyFactory.KeyFormat<AesGcmKeyFormat> createKeyFormat(
int keySize, KeyTemplate.OutputPrefixType prefixType) {
AesGcmKeyFormat format = AesGcmKeyFormat.newBuilder().setKeySize(keySize).build();
return new KeyFactory.KeyFormat<>(format, prefixType);
}
@Override
public TinkFipsUtil.AlgorithmFipsCompatibility fipsStatus() {
return TinkFipsUtil.AlgorithmFipsCompatibility.ALGORITHM_REQUIRES_BORINGCRYPTO;
};
}
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