| // Copyright 2018 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.subtle; |
| |
| import com.google.crypto.tink.Aead; |
| import com.google.crypto.tink.aead.internal.InsecureNonceXChaCha20Poly1305; |
| import com.google.crypto.tink.aead.internal.Poly1305; |
| import java.nio.ByteBuffer; |
| import java.security.GeneralSecurityException; |
| import java.util.Arrays; |
| |
| /** |
| * XChaCha20Poly1305 AEAD construction, as described in |
| * https://tools.ietf.org/html/draft-arciszewski-xchacha-01. |
| */ |
| public final class XChaCha20Poly1305 implements Aead { |
| private final InsecureNonceXChaCha20Poly1305 cipher; |
| |
| public XChaCha20Poly1305(final byte[] key) throws GeneralSecurityException { |
| cipher = new InsecureNonceXChaCha20Poly1305(key); |
| } |
| |
| @Override |
| public byte[] encrypt(final byte[] plaintext, final byte[] associatedData) |
| throws GeneralSecurityException { |
| ByteBuffer output = |
| ByteBuffer.allocate( |
| XChaCha20.NONCE_LENGTH_IN_BYTES + plaintext.length + Poly1305.MAC_TAG_SIZE_IN_BYTES); |
| byte[] nonce = Random.randBytes(XChaCha20.NONCE_LENGTH_IN_BYTES); |
| output.put(nonce); // Prepend nonce to ciphertext output. |
| cipher.encrypt(output, nonce, plaintext, associatedData); |
| return output.array(); |
| } |
| |
| @Override |
| public byte[] decrypt(final byte[] ciphertext, final byte[] associatedData) |
| throws GeneralSecurityException { |
| if (ciphertext.length < XChaCha20.NONCE_LENGTH_IN_BYTES + Poly1305.MAC_TAG_SIZE_IN_BYTES) { |
| throw new GeneralSecurityException("ciphertext too short"); |
| } |
| byte[] nonce = Arrays.copyOf(ciphertext, XChaCha20.NONCE_LENGTH_IN_BYTES); |
| ByteBuffer rawCiphertext = |
| ByteBuffer.wrap( |
| ciphertext, |
| XChaCha20.NONCE_LENGTH_IN_BYTES, |
| ciphertext.length - XChaCha20.NONCE_LENGTH_IN_BYTES); |
| return cipher.decrypt(rawCiphertext, nonce, associatedData); |
| } |
| } |