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// Copyright 2021 Google LLC
//
// 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.hybrid.internal;
import com.google.crypto.tink.HybridDecrypt;
import com.google.crypto.tink.KeyTemplate;
import com.google.crypto.tink.Registry;
import com.google.crypto.tink.internal.KeyTypeManager;
import com.google.crypto.tink.internal.PrimitiveFactory;
import com.google.crypto.tink.internal.PrivateKeyTypeManager;
import com.google.crypto.tink.proto.HpkeAead;
import com.google.crypto.tink.proto.HpkeKdf;
import com.google.crypto.tink.proto.HpkeKem;
import com.google.crypto.tink.proto.HpkeKeyFormat;
import com.google.crypto.tink.proto.HpkeParams;
import com.google.crypto.tink.proto.HpkePrivateKey;
import com.google.crypto.tink.proto.HpkePublicKey;
import com.google.crypto.tink.proto.KeyData.KeyMaterialType;
import com.google.crypto.tink.subtle.EllipticCurves;
import com.google.crypto.tink.subtle.Validators;
import com.google.crypto.tink.subtle.X25519;
import com.google.protobuf.ByteString;
import com.google.protobuf.ExtensionRegistryLite;
import com.google.protobuf.InvalidProtocolBufferException;
import java.security.GeneralSecurityException;
import java.security.KeyPair;
import java.security.interfaces.ECPrivateKey;
import java.security.interfaces.ECPublicKey;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* Key manager that generates new {@link HpkePrivateKey} keys and produces new instances of {@link
* HpkeDecrypt} primitives.
*/
public final class HpkePrivateKeyManager
extends PrivateKeyTypeManager<HpkePrivateKey, HpkePublicKey> {
public HpkePrivateKeyManager() {
super(
HpkePrivateKey.class,
HpkePublicKey.class,
new PrimitiveFactory<HybridDecrypt, HpkePrivateKey>(HybridDecrypt.class) {
@Override
public HybridDecrypt getPrimitive(HpkePrivateKey recipientPrivateKey)
throws GeneralSecurityException {
return HpkeDecrypt.createHpkeDecrypt(recipientPrivateKey);
}
});
}
/**
* Registers an {@link HpkePrivateKeyManager} and an {@link HpkePublicKeyManager} with the
* registry, so that HpkePrivateKey and HpkePublicKey key types can be used with Tink.
*/
public static void registerPair(boolean newKeyAllowed) throws GeneralSecurityException {
Registry.registerAsymmetricKeyManagers(
new HpkePrivateKeyManager(), new HpkePublicKeyManager(), newKeyAllowed);
}
@Override
public String getKeyType() {
return "type.googleapis.com/google.crypto.tink.HpkePrivateKey";
}
@Override
public int getVersion() {
return 0;
}
@Override
public HpkePublicKey getPublicKey(HpkePrivateKey key) {
return key.getPublicKey();
}
@Override
public KeyMaterialType keyMaterialType() {
return KeyMaterialType.ASYMMETRIC_PRIVATE;
}
@Override
public HpkePrivateKey parseKey(ByteString byteString) throws InvalidProtocolBufferException {
return HpkePrivateKey.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry());
}
@Override
public void validateKey(HpkePrivateKey key) throws GeneralSecurityException {
if (key.getPrivateKey().isEmpty()) {
throw new GeneralSecurityException("Private key is empty.");
}
if (!key.hasPublicKey()) {
throw new GeneralSecurityException("Missing public key.");
}
Validators.validateVersion(key.getVersion(), getVersion());
HpkeUtil.validateParams(key.getPublicKey().getParams());
}
@Override
public KeyTypeManager.KeyFactory<HpkeKeyFormat, HpkePrivateKey> keyFactory() {
return new KeyTypeManager.KeyFactory<HpkeKeyFormat, HpkePrivateKey>(HpkeKeyFormat.class) {
@Override
public void validateKeyFormat(HpkeKeyFormat keyFormat) throws GeneralSecurityException {
HpkeUtil.validateParams(keyFormat.getParams());
}
@Override
public HpkeKeyFormat parseKeyFormat(ByteString byteString)
throws InvalidProtocolBufferException {
return HpkeKeyFormat.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry());
}
@Override
public HpkePrivateKey createKey(HpkeKeyFormat keyFormat) throws GeneralSecurityException {
byte[] privateKeyBytes;
byte[] publicKeyBytes;
switch (keyFormat.getParams().getKem()) {
case DHKEM_X25519_HKDF_SHA256:
privateKeyBytes = X25519.generatePrivateKey();
publicKeyBytes = X25519.publicFromPrivate(privateKeyBytes);
break;
case DHKEM_P256_HKDF_SHA256:
case DHKEM_P384_HKDF_SHA384:
case DHKEM_P521_HKDF_SHA512:
EllipticCurves.CurveType curveType =
HpkeUtil.nistHpkeKemToCurve(keyFormat.getParams().getKem());
KeyPair keyPair = EllipticCurves.generateKeyPair(curveType);
publicKeyBytes =
EllipticCurves.pointEncode(
curveType,
EllipticCurves.PointFormatType.UNCOMPRESSED,
((ECPublicKey) keyPair.getPublic()).getW());
privateKeyBytes = ((ECPrivateKey) keyPair.getPrivate()).getS().toByteArray();
break;
default:
throw new GeneralSecurityException("Invalid KEM");
}
HpkePublicKey publicKey =
HpkePublicKey.newBuilder()
.setVersion(getVersion())
.setParams(keyFormat.getParams())
.setPublicKey(ByteString.copyFrom(publicKeyBytes))
.build();
return HpkePrivateKey.newBuilder()
.setVersion(getVersion())
.setPublicKey(publicKey)
.setPrivateKey(ByteString.copyFrom(privateKeyBytes))
.build();
}
@Override
public Map<String, KeyFactory.KeyFormat<HpkeKeyFormat>> keyFormats() {
Map<String, KeyFactory.KeyFormat<HpkeKeyFormat>> result = new HashMap<>();
result.put(
"DHKEM_X25519_HKDF_SHA256_HKDF_SHA256_AES_128_GCM",
createKeyFormat(
HpkeKem.DHKEM_X25519_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_X25519_HKDF_SHA256_HKDF_SHA256_AES_128_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_X25519_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_X25519_HKDF_SHA256_HKDF_SHA256_AES_256_GCM",
createKeyFormat(
HpkeKem.DHKEM_X25519_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_X25519_HKDF_SHA256_HKDF_SHA256_AES_256_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_X25519_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_X25519_HKDF_SHA256_HKDF_SHA256_CHACHA20_POLY1305",
createKeyFormat(
HpkeKem.DHKEM_X25519_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.CHACHA20_POLY1305,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_X25519_HKDF_SHA256_HKDF_SHA256_CHACHA20_POLY1305_RAW",
createKeyFormat(
HpkeKem.DHKEM_X25519_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.CHACHA20_POLY1305,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_P256_HKDF_SHA256_HKDF_SHA256_AES_128_GCM",
createKeyFormat(
HpkeKem.DHKEM_P256_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_P256_HKDF_SHA256_HKDF_SHA256_AES_128_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_P256_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_P256_HKDF_SHA256_HKDF_SHA256_AES_256_GCM",
createKeyFormat(
HpkeKem.DHKEM_P256_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_P256_HKDF_SHA256_HKDF_SHA256_AES_256_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_P256_HKDF_SHA256,
HpkeKdf.HKDF_SHA256,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_P384_HKDF_SHA384_HKDF_SHA384_AES_128_GCM",
createKeyFormat(
HpkeKem.DHKEM_P384_HKDF_SHA384,
HpkeKdf.HKDF_SHA384,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_P384_HKDF_SHA384_HKDF_SHA384_AES_128_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_P384_HKDF_SHA384,
HpkeKdf.HKDF_SHA384,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_P384_HKDF_SHA384_HKDF_SHA384_AES_256_GCM",
createKeyFormat(
HpkeKem.DHKEM_P384_HKDF_SHA384,
HpkeKdf.HKDF_SHA384,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_P384_HKDF_SHA384_HKDF_SHA384_AES_256_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_P384_HKDF_SHA384,
HpkeKdf.HKDF_SHA384,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_P521_HKDF_SHA512_HKDF_SHA512_AES_128_GCM",
createKeyFormat(
HpkeKem.DHKEM_P521_HKDF_SHA512,
HpkeKdf.HKDF_SHA512,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_P521_HKDF_SHA512_HKDF_SHA512_AES_128_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_P521_HKDF_SHA512,
HpkeKdf.HKDF_SHA512,
HpkeAead.AES_128_GCM,
KeyTemplate.OutputPrefixType.RAW));
result.put(
"DHKEM_P521_HKDF_SHA512_HKDF_SHA512_AES_256_GCM",
createKeyFormat(
HpkeKem.DHKEM_P521_HKDF_SHA512,
HpkeKdf.HKDF_SHA512,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.TINK));
result.put(
"DHKEM_P521_HKDF_SHA512_HKDF_SHA512_AES_256_GCM_RAW",
createKeyFormat(
HpkeKem.DHKEM_P521_HKDF_SHA512,
HpkeKdf.HKDF_SHA512,
HpkeAead.AES_256_GCM,
KeyTemplate.OutputPrefixType.RAW));
return Collections.unmodifiableMap(result);
}
};
}
private static KeyFactory.KeyFormat<HpkeKeyFormat> createKeyFormat(
HpkeKem kem, HpkeKdf kdf, HpkeAead aead, KeyTemplate.OutputPrefixType prefixType) {
HpkeParams params = HpkeParams.newBuilder().setKem(kem).setKdf(kdf).setAead(aead).build();
return new KeyFactory.KeyFormat<>(
HpkeKeyFormat.newBuilder().setParams(params).build(), prefixType);
}
}
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