| // 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.mac; |
| |
| import com.google.crypto.tink.KeyTemplate; |
| import com.google.crypto.tink.Mac; |
| 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.proto.AesCmacKey; |
| import com.google.crypto.tink.proto.AesCmacKeyFormat; |
| import com.google.crypto.tink.proto.AesCmacParams; |
| import com.google.crypto.tink.proto.KeyData.KeyMaterialType; |
| import com.google.crypto.tink.subtle.PrfAesCmac; |
| import com.google.crypto.tink.subtle.PrfMac; |
| 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.security.GeneralSecurityException; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| /** |
| * This key manager generates new {@code AesCmacKey} keys and produces new instances of {@code |
| * AesCmac}. |
| */ |
| public final class AesCmacKeyManager extends KeyTypeManager<AesCmacKey> { |
| AesCmacKeyManager() { |
| super( |
| AesCmacKey.class, |
| new PrimitiveFactory<Mac, AesCmacKey>(Mac.class) { |
| @Override |
| public Mac getPrimitive(AesCmacKey key) throws GeneralSecurityException { |
| return new PrfMac( |
| new PrfAesCmac(key.getKeyValue().toByteArray()), key.getParams().getTagSize()); |
| } |
| }); |
| } |
| |
| private static final int VERSION = 0; |
| private static final int KEY_SIZE_IN_BYTES = 32; |
| private static final int MIN_TAG_SIZE_IN_BYTES = 10; |
| private static final int MAX_TAG_SIZE_IN_BYTES = 16; |
| |
| @Override |
| public String getKeyType() { |
| return "type.googleapis.com/google.crypto.tink.AesCmacKey"; |
| } |
| |
| @Override |
| public int getVersion() { |
| return VERSION; |
| } |
| |
| @Override |
| public KeyMaterialType keyMaterialType() { |
| return KeyMaterialType.SYMMETRIC; |
| } |
| |
| @Override |
| public void validateKey(AesCmacKey key) throws GeneralSecurityException { |
| Validators.validateVersion(key.getVersion(), getVersion()); |
| validateSize(key.getKeyValue().size()); |
| validateParams(key.getParams()); |
| } |
| |
| @Override |
| public AesCmacKey parseKey(ByteString byteString) throws InvalidProtocolBufferException { |
| return AesCmacKey.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry()); |
| } |
| |
| private static void validateParams(AesCmacParams params) throws GeneralSecurityException { |
| if (params.getTagSize() < MIN_TAG_SIZE_IN_BYTES) { |
| throw new GeneralSecurityException("tag size too short"); |
| } |
| if (params.getTagSize() > MAX_TAG_SIZE_IN_BYTES) { |
| throw new GeneralSecurityException("tag size too long"); |
| } |
| } |
| |
| private static void validateSize(int size) throws GeneralSecurityException { |
| if (size != KEY_SIZE_IN_BYTES) { |
| throw new GeneralSecurityException("AesCmacKey size wrong, must be 32 bytes"); |
| } |
| } |
| |
| @Override |
| public KeyFactory<AesCmacKeyFormat, AesCmacKey> keyFactory() { |
| return new KeyFactory<AesCmacKeyFormat, AesCmacKey>(AesCmacKeyFormat.class) { |
| @Override |
| public void validateKeyFormat(AesCmacKeyFormat format) throws GeneralSecurityException { |
| validateParams(format.getParams()); |
| validateSize(format.getKeySize()); |
| } |
| |
| @Override |
| public AesCmacKeyFormat parseKeyFormat(ByteString byteString) |
| throws InvalidProtocolBufferException { |
| return AesCmacKeyFormat.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry()); |
| } |
| |
| @Override |
| public AesCmacKey createKey(AesCmacKeyFormat format) throws GeneralSecurityException { |
| return AesCmacKey.newBuilder() |
| .setVersion(VERSION) |
| .setKeyValue(ByteString.copyFrom(Random.randBytes(format.getKeySize()))) |
| .setParams(format.getParams()) |
| .build(); |
| } |
| |
| @Override |
| public Map<String, KeyFactory.KeyFormat<AesCmacKeyFormat>> keyFormats() |
| throws GeneralSecurityException { |
| Map<String, KeyFactory.KeyFormat<AesCmacKeyFormat>> result = new HashMap<>(); |
| result.put( |
| "AES_CMAC", // backward compatibility with MacKeyTemplates |
| new KeyFactory.KeyFormat<>( |
| AesCmacKeyFormat.newBuilder() |
| .setKeySize(32) |
| .setParams(AesCmacParams.newBuilder().setTagSize(16).build()) |
| .build(), |
| KeyTemplate.OutputPrefixType.TINK)); |
| result.put( |
| "AES256_CMAC", |
| new KeyFactory.KeyFormat<>( |
| AesCmacKeyFormat.newBuilder() |
| .setKeySize(32) |
| .setParams(AesCmacParams.newBuilder().setTagSize(16).build()) |
| .build(), |
| KeyTemplate.OutputPrefixType.TINK)); |
| result.put( |
| "AES256_CMAC_RAW", |
| new KeyFactory.KeyFormat<>( |
| AesCmacKeyFormat.newBuilder() |
| .setKeySize(32) |
| .setParams(AesCmacParams.newBuilder().setTagSize(16).build()) |
| .build(), |
| KeyTemplate.OutputPrefixType.RAW)); |
| return Collections.unmodifiableMap(result); |
| } |
| }; |
| } |
| |
| public static void register(boolean newKeyAllowed) throws GeneralSecurityException { |
| Registry.registerKeyManager(new AesCmacKeyManager(), newKeyAllowed); |
| AesCmacProtoSerialization.register(); |
| } |
| |
| /** |
| * @return A {@link KeyTemplate} that generates new instances of AES-CMAC keys with the following |
| * parameters: |
| * <ul> |
| * <li>Key size: 32 bytes |
| * <li>Tag size: 16 bytes |
| * <li>Prefix type: {@link KeyTemplate.OutputPrefixType#TINK} |
| * </ul> |
| * |
| * @deprecated use {@code KeyTemplates.get("AES256_CMAC")} |
| */ |
| @Deprecated |
| public static final KeyTemplate aes256CmacTemplate() { |
| AesCmacKeyFormat format = |
| AesCmacKeyFormat.newBuilder() |
| .setKeySize(32) |
| .setParams(AesCmacParams.newBuilder().setTagSize(16).build()) |
| .build(); |
| return KeyTemplate.create( |
| new AesCmacKeyManager().getKeyType(), |
| format.toByteArray(), |
| KeyTemplate.OutputPrefixType.TINK); |
| } |
| |
| /** |
| * @return A {@link KeyTemplate} that generates new instances of AES-CMAC keys with the following |
| * parameters: |
| * <ul> |
| * <li>Key size: 32 bytes |
| * <li>Tag size: 16 bytes |
| * <li>Prefix type: {@link KeyTemplate.OutputPrefixType#RAW} (no prefix) |
| * </ul> |
| * |
| * @deprecated use {@code KeyTemplates.get("AES256_CMAC_RAW")} |
| */ |
| @Deprecated |
| public static final KeyTemplate rawAes256CmacTemplate() { |
| AesCmacKeyFormat format = |
| AesCmacKeyFormat.newBuilder() |
| .setKeySize(32) |
| .setParams(AesCmacParams.newBuilder().setTagSize(16).build()) |
| .build(); |
| return KeyTemplate.create( |
| new AesCmacKeyManager().getKeyType(), |
| format.toByteArray(), |
| KeyTemplate.OutputPrefixType.RAW); |
| } |
| } |