| /* |
| * Copyright (C) 2020 The Android Open Source Project |
| * |
| * 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.android.server.locksettings; |
| |
| import java.io.ByteArrayInputStream; |
| import java.io.ByteArrayOutputStream; |
| import java.io.DataInputStream; |
| import java.io.DataOutputStream; |
| import java.io.IOException; |
| import java.security.InvalidAlgorithmParameterException; |
| import java.security.InvalidKeyException; |
| import java.security.NoSuchAlgorithmException; |
| import java.util.Objects; |
| |
| import javax.crypto.BadPaddingException; |
| import javax.crypto.Cipher; |
| import javax.crypto.IllegalBlockSizeException; |
| import javax.crypto.NoSuchPaddingException; |
| import javax.crypto.SecretKey; |
| import javax.crypto.spec.GCMParameterSpec; |
| |
| class AesEncryptionUtil { |
| /** The algorithm used for the encryption of the key blob. */ |
| private static final String CIPHER_ALGO = "AES/GCM/NoPadding"; |
| |
| private AesEncryptionUtil() {} |
| |
| static byte[] decrypt(SecretKey key, DataInputStream cipherStream) throws IOException { |
| Objects.requireNonNull(key); |
| Objects.requireNonNull(cipherStream); |
| |
| int ivSize = cipherStream.readInt(); |
| if (ivSize < 0 || ivSize > 32) { |
| throw new IOException("IV out of range: " + ivSize); |
| } |
| byte[] iv = new byte[ivSize]; |
| cipherStream.readFully(iv); |
| |
| int rawCipherTextSize = cipherStream.readInt(); |
| if (rawCipherTextSize < 0) { |
| throw new IOException("Invalid cipher text size: " + rawCipherTextSize); |
| } |
| |
| byte[] rawCipherText = new byte[rawCipherTextSize]; |
| cipherStream.readFully(rawCipherText); |
| |
| final byte[] plainText; |
| try { |
| Cipher c = Cipher.getInstance(CIPHER_ALGO); |
| c.init(Cipher.DECRYPT_MODE, key, new GCMParameterSpec(128, iv)); |
| plainText = c.doFinal(rawCipherText); |
| } catch (NoSuchAlgorithmException | InvalidKeyException | BadPaddingException |
| | IllegalBlockSizeException | NoSuchPaddingException |
| | InvalidAlgorithmParameterException e) { |
| throw new IOException("Could not decrypt cipher text", e); |
| } |
| |
| return plainText; |
| } |
| |
| static byte[] decrypt(SecretKey key, byte[] cipherText) throws IOException { |
| Objects.requireNonNull(key); |
| Objects.requireNonNull(cipherText); |
| |
| DataInputStream cipherStream = new DataInputStream(new ByteArrayInputStream(cipherText)); |
| return decrypt(key, cipherStream); |
| } |
| |
| static byte[] encrypt(SecretKey key, byte[] plainText) throws IOException { |
| Objects.requireNonNull(key); |
| Objects.requireNonNull(plainText); |
| |
| ByteArrayOutputStream bos = new ByteArrayOutputStream(); |
| DataOutputStream dos = new DataOutputStream(bos); |
| |
| final byte[] cipherText; |
| final byte[] iv; |
| try { |
| Cipher cipher = Cipher.getInstance(CIPHER_ALGO); |
| cipher.init(Cipher.ENCRYPT_MODE, key); |
| cipherText = cipher.doFinal(plainText); |
| iv = cipher.getIV(); |
| } catch (NoSuchAlgorithmException | BadPaddingException | IllegalBlockSizeException |
| | NoSuchPaddingException | InvalidKeyException e) { |
| throw new IOException("Could not encrypt input data", e); |
| } |
| |
| dos.writeInt(iv.length); |
| dos.write(iv); |
| dos.writeInt(cipherText.length); |
| dos.write(cipherText); |
| |
| return bos.toByteArray(); |
| } |
| } |