Java tutorial
package org.bouncycastle.crypto.engines; import org.bouncycastle.crypto.BlockCipher; import org.bouncycastle.crypto.CipherParameters; import org.bouncycastle.crypto.DataLengthException; import org.bouncycastle.crypto.OutputLengthException; import org.bouncycastle.crypto.params.KeyParameter; import org.bouncycastle.crypto.params.RC2Parameters; /** * an implementation of RC2 as described in RFC 2268 * "A Description of the RC2(r) Encryption Algorithm" R. Rivest. */ public class RC2Engine implements BlockCipher { // // the values we use for key expansion (based on the digits of PI) // private static byte[] piTable = { (byte) 0xd9, (byte) 0x78, (byte) 0xf9, (byte) 0xc4, (byte) 0x19, (byte) 0xdd, (byte) 0xb5, (byte) 0xed, (byte) 0x28, (byte) 0xe9, (byte) 0xfd, (byte) 0x79, (byte) 0x4a, (byte) 0xa0, (byte) 0xd8, (byte) 0x9d, (byte) 0xc6, (byte) 0x7e, (byte) 0x37, (byte) 0x83, (byte) 0x2b, (byte) 0x76, (byte) 0x53, (byte) 0x8e, (byte) 0x62, (byte) 0x4c, (byte) 0x64, (byte) 0x88, (byte) 0x44, (byte) 0x8b, (byte) 0xfb, (byte) 0xa2, (byte) 0x17, (byte) 0x9a, (byte) 0x59, (byte) 0xf5, (byte) 0x87, (byte) 0xb3, (byte) 0x4f, (byte) 0x13, (byte) 0x61, (byte) 0x45, (byte) 0x6d, (byte) 0x8d, (byte) 0x9, (byte) 0x81, (byte) 0x7d, (byte) 0x32, (byte) 0xbd, (byte) 0x8f, (byte) 0x40, (byte) 0xeb, (byte) 0x86, (byte) 0xb7, (byte) 0x7b, (byte) 0xb, (byte) 0xf0, (byte) 0x95, (byte) 0x21, (byte) 0x22, (byte) 0x5c, (byte) 0x6b, (byte) 0x4e, (byte) 0x82, (byte) 0x54, (byte) 0xd6, (byte) 0x65, (byte) 0x93, (byte) 0xce, (byte) 0x60, (byte) 0xb2, (byte) 0x1c, (byte) 0x73, (byte) 0x56, (byte) 0xc0, (byte) 0x14, (byte) 0xa7, (byte) 0x8c, (byte) 0xf1, (byte) 0xdc, (byte) 0x12, (byte) 0x75, (byte) 0xca, (byte) 0x1f, (byte) 0x3b, (byte) 0xbe, (byte) 0xe4, (byte) 0xd1, (byte) 0x42, (byte) 0x3d, (byte) 0xd4, (byte) 0x30, (byte) 0xa3, (byte) 0x3c, (byte) 0xb6, (byte) 0x26, (byte) 0x6f, (byte) 0xbf, (byte) 0xe, (byte) 0xda, (byte) 0x46, (byte) 0x69, (byte) 0x7, (byte) 0x57, (byte) 0x27, (byte) 0xf2, (byte) 0x1d, (byte) 0x9b, (byte) 0xbc, (byte) 0x94, (byte) 0x43, (byte) 0x3, (byte) 0xf8, (byte) 0x11, (byte) 0xc7, (byte) 0xf6, (byte) 0x90, (byte) 0xef, (byte) 0x3e, (byte) 0xe7, (byte) 0x6, (byte) 0xc3, (byte) 0xd5, (byte) 0x2f, (byte) 0xc8, (byte) 0x66, (byte) 0x1e, (byte) 0xd7, (byte) 0x8, (byte) 0xe8, (byte) 0xea, (byte) 0xde, (byte) 0x80, (byte) 0x52, (byte) 0xee, (byte) 0xf7, (byte) 0x84, (byte) 0xaa, (byte) 0x72, (byte) 0xac, (byte) 0x35, (byte) 0x4d, (byte) 0x6a, (byte) 0x2a, (byte) 0x96, (byte) 0x1a, (byte) 0xd2, (byte) 0x71, (byte) 0x5a, (byte) 0x15, (byte) 0x49, (byte) 0x74, (byte) 0x4b, (byte) 0x9f, (byte) 0xd0, (byte) 0x5e, (byte) 0x4, (byte) 0x18, (byte) 0xa4, (byte) 0xec, (byte) 0xc2, (byte) 0xe0, (byte) 0x41, (byte) 0x6e, (byte) 0xf, (byte) 0x51, (byte) 0xcb, (byte) 0xcc, (byte) 0x24, (byte) 0x91, (byte) 0xaf, (byte) 0x50, (byte) 0xa1, (byte) 0xf4, (byte) 0x70, (byte) 0x39, (byte) 0x99, (byte) 0x7c, (byte) 0x3a, (byte) 0x85, (byte) 0x23, (byte) 0xb8, (byte) 0xb4, (byte) 0x7a, (byte) 0xfc, (byte) 0x2, (byte) 0x36, (byte) 0x5b, (byte) 0x25, (byte) 0x55, (byte) 0x97, (byte) 0x31, (byte) 0x2d, (byte) 0x5d, (byte) 0xfa, (byte) 0x98, (byte) 0xe3, (byte) 0x8a, (byte) 0x92, (byte) 0xae, (byte) 0x5, (byte) 0xdf, (byte) 0x29, (byte) 0x10, (byte) 0x67, (byte) 0x6c, (byte) 0xba, (byte) 0xc9, (byte) 0xd3, (byte) 0x0, (byte) 0xe6, (byte) 0xcf, (byte) 0xe1, (byte) 0x9e, (byte) 0xa8, (byte) 0x2c, (byte) 0x63, (byte) 0x16, (byte) 0x1, (byte) 0x3f, (byte) 0x58, (byte) 0xe2, (byte) 0x89, (byte) 0xa9, (byte) 0xd, (byte) 0x38, (byte) 0x34, (byte) 0x1b, (byte) 0xab, (byte) 0x33, (byte) 0xff, (byte) 0xb0, (byte) 0xbb, (byte) 0x48, (byte) 0xc, (byte) 0x5f, (byte) 0xb9, (byte) 0xb1, (byte) 0xcd, (byte) 0x2e, (byte) 0xc5, (byte) 0xf3, (byte) 0xdb, (byte) 0x47, (byte) 0xe5, (byte) 0xa5, (byte) 0x9c, (byte) 0x77, (byte) 0xa, (byte) 0xa6, (byte) 0x20, (byte) 0x68, (byte) 0xfe, (byte) 0x7f, (byte) 0xc1, (byte) 0xad }; private static final int BLOCK_SIZE = 8; private int[] workingKey; private boolean encrypting; private int[] generateWorkingKey(byte[] key, int bits) { int x; int[] xKey = new int[128]; for (int i = 0; i != key.length; i++) { xKey[i] = key[i] & 0xff; } // Phase 1: Expand input key to 128 bytes int len = key.length; if (len < 128) { int index = 0; x = xKey[len - 1]; do { x = piTable[(x + xKey[index++]) & 255] & 0xff; xKey[len++] = x; } while (len < 128); } // Phase 2 - reduce effective key size to "bits" len = (bits + 7) >> 3; x = piTable[xKey[128 - len] & (255 >> (7 & -bits))] & 0xff; xKey[128 - len] = x; for (int i = 128 - len - 1; i >= 0; i--) { x = piTable[x ^ xKey[i + len]] & 0xff; xKey[i] = x; } // Phase 3 - copy to newKey in little-endian order int[] newKey = new int[64]; for (int i = 0; i != newKey.length; i++) { newKey[i] = (xKey[2 * i] + (xKey[2 * i + 1] << 8)); } return newKey; } /** * initialise a RC2 cipher. * * @param encrypting whether or not we are for encryption. * @param params the parameters required to set up the cipher. * @exception IllegalArgumentException if the params argument is * inappropriate. */ public void init(boolean encrypting, CipherParameters params) { this.encrypting = encrypting; if (params instanceof RC2Parameters) { RC2Parameters param = (RC2Parameters) params; workingKey = generateWorkingKey(param.getKey(), param.getEffectiveKeyBits()); } else if (params instanceof KeyParameter) { byte[] key = ((KeyParameter) params).getKey(); workingKey = generateWorkingKey(key, key.length * 8); } else { throw new IllegalArgumentException( "invalid parameter passed to RC2 init - " + params.getClass().getName()); } } public void reset() { } public String getAlgorithmName() { return "RC2"; } public int getBlockSize() { return BLOCK_SIZE; } public final int processBlock(byte[] in, int inOff, byte[] out, int outOff) { if (workingKey == null) { throw new IllegalStateException("RC2 engine not initialised"); } if ((inOff + BLOCK_SIZE) > in.length) { throw new DataLengthException("input buffer too short"); } if ((outOff + BLOCK_SIZE) > out.length) { throw new OutputLengthException("output buffer too short"); } if (encrypting) { encryptBlock(in, inOff, out, outOff); } else { decryptBlock(in, inOff, out, outOff); } return BLOCK_SIZE; } /** * return the result rotating the 16 bit number in x left by y */ private int rotateWordLeft(int x, int y) { x &= 0xffff; return (x << y) | (x >> (16 - y)); } private void encryptBlock(byte[] in, int inOff, byte[] out, int outOff) { int x76, x54, x32, x10; x76 = ((in[inOff + 7] & 0xff) << 8) + (in[inOff + 6] & 0xff); x54 = ((in[inOff + 5] & 0xff) << 8) + (in[inOff + 4] & 0xff); x32 = ((in[inOff + 3] & 0xff) << 8) + (in[inOff + 2] & 0xff); x10 = ((in[inOff + 1] & 0xff) << 8) + (in[inOff + 0] & 0xff); for (int i = 0; i <= 16; i += 4) { x10 = rotateWordLeft(x10 + (x32 & ~x76) + (x54 & x76) + workingKey[i], 1); x32 = rotateWordLeft(x32 + (x54 & ~x10) + (x76 & x10) + workingKey[i + 1], 2); x54 = rotateWordLeft(x54 + (x76 & ~x32) + (x10 & x32) + workingKey[i + 2], 3); x76 = rotateWordLeft(x76 + (x10 & ~x54) + (x32 & x54) + workingKey[i + 3], 5); } x10 += workingKey[x76 & 63]; x32 += workingKey[x10 & 63]; x54 += workingKey[x32 & 63]; x76 += workingKey[x54 & 63]; for (int i = 20; i <= 40; i += 4) { x10 = rotateWordLeft(x10 + (x32 & ~x76) + (x54 & x76) + workingKey[i], 1); x32 = rotateWordLeft(x32 + (x54 & ~x10) + (x76 & x10) + workingKey[i + 1], 2); x54 = rotateWordLeft(x54 + (x76 & ~x32) + (x10 & x32) + workingKey[i + 2], 3); x76 = rotateWordLeft(x76 + (x10 & ~x54) + (x32 & x54) + workingKey[i + 3], 5); } x10 += workingKey[x76 & 63]; x32 += workingKey[x10 & 63]; x54 += workingKey[x32 & 63]; x76 += workingKey[x54 & 63]; for (int i = 44; i < 64; i += 4) { x10 = rotateWordLeft(x10 + (x32 & ~x76) + (x54 & x76) + workingKey[i], 1); x32 = rotateWordLeft(x32 + (x54 & ~x10) + (x76 & x10) + workingKey[i + 1], 2); x54 = rotateWordLeft(x54 + (x76 & ~x32) + (x10 & x32) + workingKey[i + 2], 3); x76 = rotateWordLeft(x76 + (x10 & ~x54) + (x32 & x54) + workingKey[i + 3], 5); } out[outOff + 0] = (byte) x10; out[outOff + 1] = (byte) (x10 >> 8); out[outOff + 2] = (byte) x32; out[outOff + 3] = (byte) (x32 >> 8); out[outOff + 4] = (byte) x54; out[outOff + 5] = (byte) (x54 >> 8); out[outOff + 6] = (byte) x76; out[outOff + 7] = (byte) (x76 >> 8); } private void decryptBlock(byte[] in, int inOff, byte[] out, int outOff) { int x76, x54, x32, x10; x76 = ((in[inOff + 7] & 0xff) << 8) + (in[inOff + 6] & 0xff); x54 = ((in[inOff + 5] & 0xff) << 8) + (in[inOff + 4] & 0xff); x32 = ((in[inOff + 3] & 0xff) << 8) + (in[inOff + 2] & 0xff); x10 = ((in[inOff + 1] & 0xff) << 8) + (in[inOff + 0] & 0xff); for (int i = 60; i >= 44; i -= 4) { x76 = rotateWordLeft(x76, 11) - ((x10 & ~x54) + (x32 & x54) + workingKey[i + 3]); x54 = rotateWordLeft(x54, 13) - ((x76 & ~x32) + (x10 & x32) + workingKey[i + 2]); x32 = rotateWordLeft(x32, 14) - ((x54 & ~x10) + (x76 & x10) + workingKey[i + 1]); x10 = rotateWordLeft(x10, 15) - ((x32 & ~x76) + (x54 & x76) + workingKey[i]); } x76 -= workingKey[x54 & 63]; x54 -= workingKey[x32 & 63]; x32 -= workingKey[x10 & 63]; x10 -= workingKey[x76 & 63]; for (int i = 40; i >= 20; i -= 4) { x76 = rotateWordLeft(x76, 11) - ((x10 & ~x54) + (x32 & x54) + workingKey[i + 3]); x54 = rotateWordLeft(x54, 13) - ((x76 & ~x32) + (x10 & x32) + workingKey[i + 2]); x32 = rotateWordLeft(x32, 14) - ((x54 & ~x10) + (x76 & x10) + workingKey[i + 1]); x10 = rotateWordLeft(x10, 15) - ((x32 & ~x76) + (x54 & x76) + workingKey[i]); } x76 -= workingKey[x54 & 63]; x54 -= workingKey[x32 & 63]; x32 -= workingKey[x10 & 63]; x10 -= workingKey[x76 & 63]; for (int i = 16; i >= 0; i -= 4) { x76 = rotateWordLeft(x76, 11) - ((x10 & ~x54) + (x32 & x54) + workingKey[i + 3]); x54 = rotateWordLeft(x54, 13) - ((x76 & ~x32) + (x10 & x32) + workingKey[i + 2]); x32 = rotateWordLeft(x32, 14) - ((x54 & ~x10) + (x76 & x10) + workingKey[i + 1]); x10 = rotateWordLeft(x10, 15) - ((x32 & ~x76) + (x54 & x76) + workingKey[i]); } out[outOff + 0] = (byte) x10; out[outOff + 1] = (byte) (x10 >> 8); out[outOff + 2] = (byte) x32; out[outOff + 3] = (byte) (x32 >> 8); out[outOff + 4] = (byte) x54; out[outOff + 5] = (byte) (x54 >> 8); out[outOff + 6] = (byte) x76; out[outOff + 7] = (byte) (x76 >> 8); } }