Mercurial > projects > dcrypt
view dcrypt/crypto/modes/CBC.d @ 8:23c62e28b3a4
Reworked symmetric cipher classes to have SymmetricCipher as their superclass, and follow the general interface of init(), process(), etc. Made sure everything still passed test vectors. Removed Cipher class. I'll worry about that shit when we support something other than symmetric ciphers.
author | Thomas Dixon <reikon@reikon.us> |
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date | Mon, 18 Aug 2008 01:14:37 -0400 |
parents | 0e08791a1418 |
children | 8c7f8fecdd75 |
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/** * This file is part of the dcrypt project. * * Copyright: Copyright (C) dcrypt contributors 2008. All rights reserved. * License: MIT * Authors: Thomas Dixon */ module dcrypt.crypto.modes.CBC; import dcrypt.crypto.BlockCipher; import dcrypt.crypto.params.ParametersWithIV; version (UnitTest) { import dcrypt.crypto.ciphers.XTEA; import dcrypt.misc.Util; } /** This class implements the cipher block chaining (CBC) block mode. */ class CBC : BlockCipher { private BlockCipher m_cipher; private ubyte[] iv, previousCiphertext, cbcOutput; private bool encrypt, initialized; /** * Params: * cipher = Block cipher to wrap. */ this (BlockCipher cipher) { m_cipher = cipher; } /** Returns: The underlying cipher we are wrapping. */ BlockCipher cipher() { return m_cipher; } char[] name() { return m_cipher.name~"/CBC"; } /** * Throws: dcrypt.crypto.errors.InvalidParameterError if params aren't * an instance of dcrypt.crypto.params.ParametersWithIV. */ void init(bool encrypt, CipherParameters params) { ParametersWithIV ivParams = cast(ParametersWithIV)params; if (!ivParams) throw new InvalidParameterError( name()~": Block mode requires IV (use ParametersWithIV)"); if (ivParams.iv.length != blockSize) throw new InvalidParameterError( name()~": IV must be same length as cipher block size"); this.encrypt = encrypt; m_cipher.init(encrypt, ivParams.parameters); iv = ivParams.iv[0..blockSize]; previousCiphertext = new ubyte[blockSize]; previousCiphertext[] = iv; // C_0 = IV cbcOutput = new ubyte[blockSize]; // Output buffer for E_k/D_k(...) initialized = true; } ubyte[] process(void[] input_) { if (!initialized) throw new NotInitializedError( name()~": Block mode not initialized"); ubyte[] input = cast(ubyte[]) input_; if (input.length < blockSize) throw new ShortBufferError(name()~": Input buffer too short"); if (encrypt) { // P_i XOR C_i-1 for (int i = 0; i < blockSize; i++) previousCiphertext[i] ^= input[i]; // E_k(P_i XOR C_i-1) cbcOutput[] = m_cipher.process(previousCiphertext); // Store C_i for next block previousCiphertext[] = cbcOutput; } else { // Temporarily store C_i ubyte[] t = input[0..blockSize]; // D_k(C_i) cbcOutput[] = m_cipher.process(t); // P_i = D_k(C_i) XOR C_i-1 for (int i = 0; i < blockSize; i++) cbcOutput[i] ^= previousCiphertext[i]; // Store C_i for next block previousCiphertext[] = t; } return cbcOutput; } uint blockSize() { return m_cipher.blockSize; } void reset() { previousCiphertext[] = iv; m_cipher.reset(); } /** Test vectors for CBC mode. Assumes XTEA passes test vectors. */ version (UnitTest) { unittest { static const char[][] test_keys = [ "00000000000000000000000000000000", "00000000000000000000000000000000", "0123456789abcdef0123456789abcdef" ]; static const char[][] test_plaintexts = [ "00000000000000000000000000000000"~ "00000000000000000000000000000000", "41414141414141414141414141414141"~ "41414141414141414141414141414141", "01010101010101010101010101010101"~ "01010101010101010101010101010101" ]; static const char[][] test_ciphertexts = [ "dee9d4d8f7131ed9b0e40a036a85d2c4"~ "4602d6e67f0c603738197998166ef281", "ed23375a821a8c2d0e1f03d719874eaa"~ "4b71be74f261e22f4cd2285883a61a23", "c09d3c606614d84b8d184fa29c5cb5f6"~ "f26fa5a0b6b63ba0f7ebf2f8735f85e3" ]; XTEA x = new XTEA(); CBC c = new CBC(x); ubyte[] iv = new ubyte[x.blockSize], // Initialized to 0 buffer = new ubyte[32]; char[] result; for (int i = 0; i < test_keys.length; i++) { SymmetricKey key = new SymmetricKey(Util.hexToUbytes(test_keys[i])); ParametersWithIV params = new ParametersWithIV(key, iv); // Encryption c.init(true, params); for (int j = 0; j < 32; j+=x.blockSize) buffer[j..j+x.blockSize] = c.process(Util.hexToUbytes(test_plaintexts[i])[j..j+x.blockSize]); result = Util.ubytesToHex(buffer); assert(result == test_ciphertexts[i], c.name()~": ("~result~") != ("~test_ciphertexts[i]~")"); // Decryption c.init(false, params); for (int j = 0; j < 32; j+=x.blockSize) buffer[j..j+x.blockSize] = c.process(Util.hexToUbytes(test_ciphertexts[i])[j..j+x.blockSize]); result = Util.ubytesToHex(buffer); assert(result == test_plaintexts[i], c.name()~": ("~result~") != ("~test_plaintexts[i]~")"); } } } }