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* accompanied this code).
*
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package com.sun.crypto.provider;
import java.security.InvalidKeyException;
/**
* Implementation of the RC2(tm) algorithm as described in RFC 2268.
*
* RC2 is a 16-bit based algorithm and not particularly fast on 32/64 bit
* architectures. Also, note that although the JVM has a 16-bit integer
* type (short), all expressions are evaluated either in 32 or 64 bit
* (int or long). Expression such as "s1 = s2 + s3" are implemented by
* first promoting s2 and s3 to int, performing an int addition, and
* then demoting the result back to short to store in s1. To avoid this
* fairly slow process, we use the int type throughout and manually insert
* "& 0xffff" where necessary.
*
* @since 1.5
* @author Andreas Sterbenz
*/
final class RC2Crypt extends SymmetricCipher {
// PITABLE from the RFC, used in key setup
private final static int[] PI_TABLE = new int[] {
0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed,
0x28, 0xe9, 0xfd, 0x79, 0x4a, 0xa0, 0xd8, 0x9d,
0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e,
0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2,
0x17, 0x9a, 0x59, 0xf5, 0x87, 0xb3, 0x4f, 0x13,
0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32,
0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b,
0xf0, 0x95, 0x21, 0x22, 0x5c, 0x6b, 0x4e, 0x82,
0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c,
0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc,
0x12, 0x75, 0xca, 0x1f, 0x3b, 0xbe, 0xe4, 0xd1,
0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26,
0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57,
0x27, 0xf2, 0x1d, 0x9b, 0xbc, 0x94, 0x43, 0x03,
0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7,
0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7,
0x08, 0xe8, 0xea, 0xde, 0x80, 0x52, 0xee, 0xf7,
0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a,
0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74,
0x4b, 0x9f, 0xd0, 0x5e, 0x04, 0x18, 0xa4, 0xec,
0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc,
0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39,
0x99, 0x7c, 0x3a, 0x85, 0x23, 0xb8, 0xb4, 0x7a,
0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31,
0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae,
0x05, 0xdf, 0x29, 0x10, 0x67, 0x6c, 0xba, 0xc9,
0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c,
0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9,
0x0d, 0x38, 0x34, 0x1b, 0xab, 0x33, 0xff, 0xb0,
0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e,
0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77,
0x0a, 0xa6, 0x20, 0x68, 0xfe, 0x7f, 0xc1, 0xad,
};
// expanded key, 64 times 16-bit words
private final int[] expandedKey;
// effective key bits
private int effectiveKeyBits;
RC2Crypt() {
expandedKey = new int[64];
}
int getBlockSize() {
return 8;
}
int getEffectiveKeyBits() {
return effectiveKeyBits;
}
/**
* Initializes the effective key bit size. This method is a hook to
* allow RC2Cipher to initialize the effective key size.
*/
void initEffectiveKeyBits(int effectiveKeyBits) {
this.effectiveKeyBits = effectiveKeyBits;
}
static void checkKey(String algorithm, int keyLength)
throws InvalidKeyException {
if (algorithm.equals("RC2") == false) {
throw new InvalidKeyException("Key algorithm must be RC2");
}
if ((keyLength < 5) || (keyLength > 128)) {
throw new InvalidKeyException
("RC2 key length must be between 40 and 1024 bit");
}
}
void init(boolean decrypting, String algorithm, byte[] key)
throws InvalidKeyException {
int keyLength = key.length;
if (effectiveKeyBits == 0) {
effectiveKeyBits = keyLength << 3;
}
checkKey(algorithm, keyLength);
// key buffer, the L[] byte array from the spec
byte[] expandedKeyBytes = new byte[128];
// place key into key buffer
System.arraycopy(key, 0, expandedKeyBytes, 0, keyLength);
// first loop
int t = expandedKeyBytes[keyLength - 1];
for (int i = keyLength; i < 128; i++) {
t = PI_TABLE[(t + expandedKeyBytes[i - keyLength]) & 0xff];
expandedKeyBytes[i] = (byte)t;
}
int t8 = (effectiveKeyBits + 7) >> 3;
int tm = 0xff >> (-effectiveKeyBits & 7);
// second loop, reduce search space to effective key bits
t = PI_TABLE[expandedKeyBytes[128 - t8] & tm];
expandedKeyBytes[128 - t8] = (byte)t;
for (int i = 127 - t8; i >= 0; i--) {
t = PI_TABLE[t ^ (expandedKeyBytes[i + t8] & 0xff)];
expandedKeyBytes[i] = (byte)t;
}
// byte to short conversion, little endian (copy into K[])
for (int i = 0, j = 0; i < 64; i++, j += 2) {
t = (expandedKeyBytes[j ] & 0xff)
+ ((expandedKeyBytes[j + 1] & 0xff) << 8);
expandedKey[i] = t;
}
}
/**
* Encrypt a single block. Note that in a few places we omit a "& 0xffff"
* and allow variables to become larger than 16 bit. This still works
* because there is never a 32 bit overflow.
*/
void encryptBlock(byte[] in, int inOfs, byte[] out, int outOfs) {
int R0 = (in[inOfs ] & 0xff)
+ ((in[inOfs + 1] & 0xff) << 8);
int R1 = (in[inOfs + 2] & 0xff)
+ ((in[inOfs + 3] & 0xff) << 8);
int R2 = (in[inOfs + 4] & 0xff)
+ ((in[inOfs + 5] & 0xff) << 8);
int R3 = (in[inOfs + 6] & 0xff)
+ ((in[inOfs + 7] & 0xff) << 8);
// 5 mixing rounds
for (int i = 0; i < 20; i += 4) {
R0 = (R0 + expandedKey[i ] + (R3 & R2) + (~R3 & R1)) & 0xffff;
R0 = (R0 << 1) | (R0 >>> 15);
R1 = (R1 + expandedKey[i + 1] + (R0 & R3) + (~R0 & R2)) & 0xffff;
R1 = (R1 << 2) | (R1 >>> 14);
R2 = (R2 + expandedKey[i + 2] + (R1 & R0) + (~R1 & R3)) & 0xffff;
R2 = (R2 << 3) | (R2 >>> 13);
R3 = (R3 + expandedKey[i + 3] + (R2 & R1) + (~R2 & R0)) & 0xffff;
R3 = (R3 << 5) | (R3 >>> 11);
}
// 1 mashing round
R0 += expandedKey[R3 & 0x3f];
R1 += expandedKey[R0 & 0x3f];
R2 += expandedKey[R1 & 0x3f];
R3 += expandedKey[R2 & 0x3f];
// 6 mixing rounds
for (int i = 20; i < 44; i += 4) {
R0 = (R0 + expandedKey[i ] + (R3 & R2) + (~R3 & R1)) & 0xffff;
R0 = (R0 << 1) | (R0 >>> 15);
R1 = (R1 + expandedKey[i + 1] + (R0 & R3) + (~R0 & R2)) & 0xffff;
R1 = (R1 << 2) | (R1 >>> 14);
R2 = (R2 + expandedKey[i + 2] + (R1 & R0) + (~R1 & R3)) & 0xffff;
R2 = (R2 << 3) | (R2 >>> 13);
R3 = (R3 + expandedKey[i + 3] + (R2 & R1) + (~R2 & R0)) & 0xffff;
R3 = (R3 << 5) | (R3 >>> 11);
}
// 1 mashing round
R0 += expandedKey[R3 & 0x3f];
R1 += expandedKey[R0 & 0x3f];
R2 += expandedKey[R1 & 0x3f];
R3 += expandedKey[R2 & 0x3f];
// 5 mixing rounds
for (int i = 44; i < 64; i += 4) {
R0 = (R0 + expandedKey[i ] + (R3 & R2) + (~R3 & R1)) & 0xffff;
R0 = (R0 << 1) | (R0 >>> 15);
R1 = (R1 + expandedKey[i + 1] + (R0 & R3) + (~R0 & R2)) & 0xffff;
R1 = (R1 << 2) | (R1 >>> 14);
R2 = (R2 + expandedKey[i + 2] + (R1 & R0) + (~R1 & R3)) & 0xffff;
R2 = (R2 << 3) | (R2 >>> 13);
R3 = (R3 + expandedKey[i + 3] + (R2 & R1) + (~R2 & R0)) & 0xffff;
R3 = (R3 << 5) | (R3 >>> 11);
}
out[outOfs ] = (byte)R0;
out[outOfs + 1] = (byte)(R0 >> 8);
out[outOfs + 2] = (byte)R1;
out[outOfs + 3] = (byte)(R1 >> 8);
out[outOfs + 4] = (byte)R2;
out[outOfs + 5] = (byte)(R2 >> 8);
out[outOfs + 6] = (byte)R3;
out[outOfs + 7] = (byte)(R3 >> 8);
}
void decryptBlock(byte[] in, int inOfs, byte[] out, int outOfs) {
int R0 = (in[inOfs ] & 0xff)
+ ((in[inOfs + 1] & 0xff) << 8);
int R1 = (in[inOfs + 2] & 0xff)
+ ((in[inOfs + 3] & 0xff) << 8);
int R2 = (in[inOfs + 4] & 0xff)
+ ((in[inOfs + 5] & 0xff) << 8);
int R3 = (in[inOfs + 6] & 0xff)
+ ((in[inOfs + 7] & 0xff) << 8);
// 5 r-mixing rounds
for(int i = 64; i > 44; i -= 4) {
R3 = ((R3 << 11) | (R3 >>> 5)) & 0xffff;
R3 = (R3 - expandedKey[i - 1] - (R2 & R1) - (~R2 & R0)) & 0xffff;
R2 = ((R2 << 13) | (R2 >>> 3)) & 0xffff;
R2 = (R2 - expandedKey[i - 2] - (R1 & R0) - (~R1 & R3)) & 0xffff;
R1 = ((R1 << 14) | (R1 >>> 2)) & 0xffff;
R1 = (R1 - expandedKey[i - 3] - (R0 & R3) - (~R0 & R2)) & 0xffff;
R0 = ((R0 << 15) | (R0 >>> 1)) & 0xffff;
R0 = (R0 - expandedKey[i - 4] - (R3 & R2) - (~R3 & R1)) & 0xffff;
}
// 1 r-mashing round
R3 = (R3 - expandedKey[R2 & 0x3f]) & 0xffff;
R2 = (R2 - expandedKey[R1 & 0x3f]) & 0xffff;
R1 = (R1 - expandedKey[R0 & 0x3f]) & 0xffff;
R0 = (R0 - expandedKey[R3 & 0x3f]) & 0xffff;
// 6 r-mixing rounds
for(int i = 44; i > 20; i -= 4) {
R3 = ((R3 << 11) | (R3 >>> 5)) & 0xffff;
R3 = (R3 - expandedKey[i - 1] - (R2 & R1) - (~R2 & R0)) & 0xffff;
R2 = ((R2 << 13) | (R2 >>> 3)) & 0xffff;
R2 = (R2 - expandedKey[i - 2] - (R1 & R0) - (~R1 & R3)) & 0xffff;
R1 = ((R1 << 14) | (R1 >>> 2)) & 0xffff;
R1 = (R1 - expandedKey[i - 3] - (R0 & R3) - (~R0 & R2)) & 0xffff;
R0 = ((R0 << 15) | (R0 >>> 1)) & 0xffff;
R0 = (R0 - expandedKey[i - 4] - (R3 & R2) - (~R3 & R1)) & 0xffff;
}
// 1 r-mashing round
R3 = (R3 - expandedKey[R2 & 0x3f]) & 0xffff;
R2 = (R2 - expandedKey[R1 & 0x3f]) & 0xffff;
R1 = (R1 - expandedKey[R0 & 0x3f]) & 0xffff;
R0 = (R0 - expandedKey[R3 & 0x3f]) & 0xffff;
// 5 r-mixing rounds
for(int i = 20; i > 0; i -= 4) {
R3 = ((R3 << 11) | (R3 >>> 5)) & 0xffff;
R3 = (R3 - expandedKey[i - 1] - (R2 & R1) - (~R2 & R0)) & 0xffff;
R2 = ((R2 << 13) | (R2 >>> 3)) & 0xffff;
R2 = (R2 - expandedKey[i - 2] - (R1 & R0) - (~R1 & R3)) & 0xffff;
R1 = ((R1 << 14) | (R1 >>> 2)) & 0xffff;
R1 = (R1 - expandedKey[i - 3] - (R0 & R3) - (~R0 & R2)) & 0xffff;
R0 = ((R0 << 15) | (R0 >>> 1)) & 0xffff;
R0 = (R0 - expandedKey[i - 4] - (R3 & R2) - (~R3 & R1)) & 0xffff;
}
out[outOfs ] = (byte)R0;
out[outOfs + 1] = (byte)(R0 >> 8);
out[outOfs + 2] = (byte)R1;
out[outOfs + 3] = (byte)(R1 >> 8);
out[outOfs + 4] = (byte)R2;
out[outOfs + 5] = (byte)(R2 >> 8);
out[outOfs + 6] = (byte)R3;
out[outOfs + 7] = (byte)(R3 >> 8);
}
}