mike-jumper commented on a change in pull request #576: URL: https://github.com/apache/guacamole-client/pull/576#discussion_r532286765
########## File path: extensions/guacamole-auth-json/src/main/java/org/apache/guacamole/auth/json/CryptoService.java ########## @@ -0,0 +1,215 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 org.apache.guacamole.auth.json; + +import java.security.InvalidAlgorithmParameterException; +import java.security.InvalidKeyException; +import java.security.Key; +import java.security.NoSuchAlgorithmException; +import javax.crypto.BadPaddingException; +import javax.crypto.Cipher; +import javax.crypto.IllegalBlockSizeException; +import javax.crypto.Mac; +import javax.crypto.NoSuchPaddingException; +import javax.crypto.SecretKey; +import javax.crypto.spec.IvParameterSpec; +import javax.crypto.spec.SecretKeySpec; +import org.apache.guacamole.GuacamoleException; +import org.apache.guacamole.GuacamoleServerException; + +/** + * Service for handling cryptography-related operations, such as decrypting + * encrypted data. + */ +public class CryptoService { + + /** + * The length of all signatures, in bytes. + */ + public static final int SIGNATURE_LENGTH = 32; + + /** + * The name of the key generation algorithm used for decryption. + */ + private static final String DECRYPTION_KEY_GENERATION_ALGORITHM_NAME = "AES"; + + /** + * The name of the cipher transformation that should be used to decrypt any + * String provided to decrypt(). + */ + private static final String DECRYPTION_CIPHER_NAME = "AES/CBC/PKCS5Padding"; + + /** + * The name of the key generation algorithm used for verifying signatures. + */ + private static final String SIGNATURE_KEY_GENERATION_ALGORITHM_NAME = "HmacSHA256"; + + /** + * The name of the MAC algorithm used for verifying signatures. + */ + private static final String SIGNATURE_MAC_ALGORITHM_NAME = "HmacSHA256"; + + /** + * IV which is all null bytes (all binary zeroes). Usually, using a null IV + * is a horrible idea. As our plaintext will always be prepended with the + * HMAC signature of the rest of the message, we are effectively using the + * HMAC signature itself as the IV. For our purposes, where the encrypted + * value becomes an authentication token, this is OK. + */ + private static final IvParameterSpec NULL_IV = new IvParameterSpec(new byte[] { + 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0 + }); + + /** + * Creates a new key suitable for decryption using the provided raw key + * bytes. The algorithm used to generate this key is dictated by + * DECRYPTION_KEY_GENERATION_ALGORITHM_NAME and must match the algorithm + * used by decrypt(). + * + * @param keyBytes + * The raw bytes from which the encryption/decryption key should be + * generated. + * + * @return + * A new key suitable for encryption or decryption, generated from the + * given bytes. + */ + public SecretKey createEncryptionKey(byte[] keyBytes) { + return new SecretKeySpec(keyBytes, DECRYPTION_KEY_GENERATION_ALGORITHM_NAME); + } + + /** + * Creates a new key suitable for signature verification using the provided + * raw key bytes. The algorithm used to generate this key is dictated by + * SIGNATURE_KEY_GENERATION_ALGORITHM_NAME and must match the algorithm + * used by sign(). + * + * @param keyBytes + * The raw bytes from which the signature verification key should be + * generated. + * + * @return + * A new key suitable for signature verification, generated from the + * given bytes. + */ + public SecretKey createSignatureKey(byte[] keyBytes) { + return new SecretKeySpec(keyBytes, SIGNATURE_KEY_GENERATION_ALGORITHM_NAME); + } + + /** + * Decrypts the given ciphertext using the provided key, returning the + * resulting plaintext. If any error occurs during decryption at all, a + * GuacamoleException is thrown. The IV used for the decryption process is + * a null IV (all binary zeroes). + * + * @param key + * The key to use to decrypt the provided ciphertext. + * + * @param cipherText + * The ciphertext to decrypt. + * + * @return + * The plaintext which results from decrypting the ciphertext with the + * provided key. + * + * @throws GuacamoleException + * If any error at all occurs during decryption. + */ + public byte[] decrypt(Key key, byte[] cipherText) throws GuacamoleException { + + try { + + // Init cipher for descryption using secret key + Cipher cipher = Cipher.getInstance(DECRYPTION_CIPHER_NAME); + cipher.init(Cipher.DECRYPT_MODE, key, NULL_IV); + + // Perform decryption + return cipher.doFinal(cipherText); + + } + + // Rethrow all decryption failures identically + catch (InvalidAlgorithmParameterException e) { + throw new GuacamoleServerException(e); + } + catch (NoSuchAlgorithmException e) { + throw new GuacamoleServerException(e); + } + catch (NoSuchPaddingException e) { + throw new GuacamoleServerException(e); + } + catch (InvalidKeyException e) { + throw new GuacamoleServerException(e); + } + catch (IllegalBlockSizeException e) { + throw new GuacamoleServerException(e); + } + catch (BadPaddingException e) { + throw new GuacamoleServerException(e); + } Review comment: Sure - I'll switch instances of this over to multi-catch. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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