324 lines
8.5 KiB
C
324 lines
8.5 KiB
C
/**********************************************************************\
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* To commemorate the 1996 RSA Data Security Conference, the following *
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* code is released into the public domain by its author. Prost! *
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* *
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* This cipher uses 16-bit words and little-endian byte ordering. *
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* I wonder which processor it was optimized for? *
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* *
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* Thanks to CodeView, SoftIce, and D86 for helping bring this code to *
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* the public. *
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\**********************************************************************/
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/* modified in order to use the libmcrypt API by Nikos Mavroyanopoulos
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* All modifications are placed under the license of libmcrypt.
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*/
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/* $Id: rc2.c,v 1.1 2007/07/19 06:11:48 pizon Exp $ */
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#include <libdefs.h>
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#include <mcrypt_modules.h>
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/* #include <assert.h> */
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#include "rc2.h"
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#define _mcrypt_set_key rc2_LTX__mcrypt_set_key
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#define _mcrypt_encrypt rc2_LTX__mcrypt_encrypt
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#define _mcrypt_decrypt rc2_LTX__mcrypt_decrypt
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#define _mcrypt_get_size rc2_LTX__mcrypt_get_size
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#define _mcrypt_get_block_size rc2_LTX__mcrypt_get_block_size
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#define _is_block_algorithm rc2_LTX__is_block_algorithm
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#define _mcrypt_get_key_size rc2_LTX__mcrypt_get_key_size
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#define _mcrypt_get_supported_key_sizes rc2_LTX__mcrypt_get_supported_key_sizes
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#define _mcrypt_get_algorithms_name rc2_LTX__mcrypt_get_algorithms_name
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#define _mcrypt_self_test rc2_LTX__mcrypt_self_test
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#define _mcrypt_algorithm_version rc2_LTX__mcrypt_algorithm_version
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/**********************************************************************\
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* Expand a variable-length user key (between 1 and 128 bytes) to a *
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* 64-short working rc2 key, of at most "bits" effective key bits. *
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* The effective key bits parameter looks like an export control hack. *
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* For normal use, it should always be set to 1024. For convenience, *
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* zero is accepted as an alias for 1024. *
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\**********************************************************************/
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WIN32DLL_DEFINE
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int _mcrypt_set_key(word16 * xkey, const byte * key, unsigned int len)
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{
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unsigned int j;
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byte *xkey_p = (void *) xkey;
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int i;
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/* 256-entry permutation table, probably derived somehow from pi */
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static const byte permute[256] = {
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217, 120, 249, 196, 25, 221, 181, 237, 40, 233, 253, 121,
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74, 160, 216, 157,
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198, 126, 55, 131, 43, 118, 83, 142, 98, 76, 100, 136,
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68, 139, 251, 162,
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23, 154, 89, 245, 135, 179, 79, 19, 97, 69, 109, 141, 9,
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129, 125, 50,
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189, 143, 64, 235, 134, 183, 123, 11, 240, 149, 33, 34,
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92, 107, 78, 130,
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84, 214, 101, 147, 206, 96, 178, 28, 115, 86, 192, 20,
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167, 140, 241, 220,
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18, 117, 202, 31, 59, 190, 228, 209, 66, 61, 212, 48,
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163, 60, 182, 38,
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111, 191, 14, 218, 70, 105, 7, 87, 39, 242, 29, 155, 188,
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148, 67, 3,
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248, 17, 199, 246, 144, 239, 62, 231, 6, 195, 213, 47,
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200, 102, 30, 215,
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8, 232, 234, 222, 128, 82, 238, 247, 132, 170, 114, 172,
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53, 77, 106, 42,
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150, 26, 210, 113, 90, 21, 73, 116, 75, 159, 208, 94, 4,
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24, 164, 236,
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194, 224, 65, 110, 15, 81, 203, 204, 36, 145, 175, 80,
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161, 244, 112, 57,
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153, 124, 58, 133, 35, 184, 180, 122, 252, 2, 54, 91, 37,
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85, 151, 49,
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45, 93, 250, 152, 227, 138, 146, 174, 5, 223, 41, 16,
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103, 108, 186, 201,
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211, 0, 230, 207, 225, 158, 168, 44, 99, 22, 1, 63, 88,
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226, 137, 169,
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13, 56, 52, 27, 171, 51, 255, 176, 187, 72, 12, 95, 185,
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177, 205, 46,
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197, 243, 219, 71, 229, 165, 156, 119, 10, 166, 32, 104,
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254, 127, 193, 173
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};
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/* assert(len > 0 && len <= 128); */
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memmove(xkey, key, len);
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/* Phase 1: Expand input key to 128 bytes */
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for (j = len; j < 128; j++) {
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xkey_p[j] =
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permute[(xkey_p[j - len] + xkey_p[j - 1]) % 256];
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}
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xkey_p[0] = permute[xkey_p[0]];
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/* Phase 2 - reduce effective key size to "bits" */
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/* stripped */
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/* Phase 3 - copy to xkey in little-endian order */
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i = 63;
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do {
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xkey[i] = xkey_p[2 * i] + (xkey_p[2 * i + 1] << 8);
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} while (i--);
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return 0;
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}
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/**********************************************************************\
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* Encrypt an 8-byte block of plaintext using the given key. *
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\**********************************************************************/
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WIN32DLL_DEFINE void _mcrypt_encrypt(const word16 * xkey, word16 * plain)
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{
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word16 x3, x2, x1, x0, i;
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#ifdef WORDS_BIGENDIAN
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x3 = byteswap16(plain[3]);
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x2 = byteswap16(plain[2]);
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x1 = byteswap16(plain[1]);
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x0 = byteswap16(plain[0]);
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#else
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x3 = plain[3];
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x2 = plain[2];
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x1 = plain[1];
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x0 = plain[0];
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#endif
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for (i = 0; i < 16; i++) {
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x0 += (x1 & ~x3) + (x2 & x3) + xkey[4 * i + 0];
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x0 = rotl16(x0, 1);
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x1 += (x2 & ~x0) + (x3 & x0) + xkey[4 * i + 1];
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x1 = rotl16(x1, 2);
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x2 += (x3 & ~x1) + (x0 & x1) + xkey[4 * i + 2];
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x2 = rotl16(x2, 3);
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x3 += (x0 & ~x2) + (x1 & x2) + xkey[4 * i + 3];
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x3 = rotl16(x3, 5);
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if (i == 4 || i == 10) {
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x0 += xkey[x3 & 63];
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x1 += xkey[x0 & 63];
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x2 += xkey[x1 & 63];
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x3 += xkey[x2 & 63];
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}
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}
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#ifdef WORDS_BIGENDIAN
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plain[0] = byteswap16(x0);
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plain[1] = byteswap16(x1);
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plain[2] = byteswap16(x2);
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plain[3] = byteswap16(x3);
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#else
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plain[0] = (x0);
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plain[1] = (x1);
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plain[2] = (x2);
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plain[3] = (x3);
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#endif
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}
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/**********************************************************************\
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* Decrypt an 8-byte block of ciphertext using the given key. *
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\**********************************************************************/
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WIN32DLL_DEFINE void _mcrypt_decrypt(const word16 * xkey, word16 * plain)
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{
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word16 x3, x2, x1, x0, i;
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#ifndef WORDS_BIGENDIAN
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x3 = plain[3];
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x2 = plain[2];
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x1 = plain[1];
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x0 = plain[0];
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#else
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x3 = byteswap16(plain[3]);
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x2 = byteswap16(plain[2]);
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x1 = byteswap16(plain[1]);
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x0 = byteswap16(plain[0]);
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#endif
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i = 15;
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do {
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x3 = rotr16(x3, 5);
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x3 -= (x0 & ~x2) + (x1 & x2) + xkey[4 * i + 3];
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x2 = rotr16(x2, 3);
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x2 -= (x3 & ~x1) + (x0 & x1) + xkey[4 * i + 2];
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x1 = rotr16(x1, 2);
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x1 -= (x2 & ~x0) + (x3 & x0) + xkey[4 * i + 1];
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x0 = rotr16(x0, 1);
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x0 -= (x1 & ~x3) + (x2 & x3) + xkey[4 * i + 0];
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if (i == 5 || i == 11) {
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x3 -= xkey[x2 & 63];
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x2 -= xkey[x1 & 63];
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x1 -= xkey[x0 & 63];
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x0 -= xkey[x3 & 63];
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}
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} while (i--);
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#ifdef WORDS_BIGENDIAN
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plain[0] = byteswap16(x0);
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plain[1] = byteswap16(x1);
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plain[2] = byteswap16(x2);
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plain[3] = byteswap16(x3);
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#else
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plain[0] = x0;
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plain[1] = x1;
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plain[2] = x2;
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plain[3] = x3;
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#endif
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}
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WIN32DLL_DEFINE int _mcrypt_get_size()
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{
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return 64 * sizeof(word16);
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}
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WIN32DLL_DEFINE int _mcrypt_get_block_size()
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{
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return 8;
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}
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WIN32DLL_DEFINE int _is_block_algorithm()
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{
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return 1;
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}
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WIN32DLL_DEFINE int _mcrypt_get_key_size()
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{
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return 128;
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}
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WIN32DLL_DEFINE const int *_mcrypt_get_supported_key_sizes(int *len)
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{
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*len = 0;
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return NULL;
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}
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WIN32DLL_DEFINE char *_mcrypt_get_algorithms_name()
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{
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return "RC2";
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}
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#define CIPHER "becbe4c8e6237a14"
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WIN32DLL_DEFINE int _mcrypt_self_test()
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{
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char *keyword;
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unsigned char plaintext[16];
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unsigned char ciphertext[16];
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int blocksize = _mcrypt_get_block_size(), j;
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void *key;
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unsigned char cipher_tmp[200];
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keyword = calloc(1, _mcrypt_get_key_size());
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if (keyword == NULL)
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return -1;
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for (j = 0; j < _mcrypt_get_key_size(); j++) {
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keyword[j] = ((j * 2 + 10) % 256);
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}
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for (j = 0; j < blocksize; j++) {
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plaintext[j] = j % 256;
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}
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key = malloc(_mcrypt_get_size());
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if (key == NULL) {
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free(keyword);
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return -1;
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}
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memcpy(ciphertext, plaintext, blocksize);
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_mcrypt_set_key(key, (void *) keyword, _mcrypt_get_key_size());
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free(keyword);
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_mcrypt_encrypt(key, (void *) ciphertext);
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for (j = 0; j < blocksize; j++) {
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sprintf(&((char *) cipher_tmp)[2 * j], "%.2x",
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ciphertext[j]);
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}
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if (strcmp((char *) cipher_tmp, CIPHER) != 0) {
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printf("failed compatibility\n");
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printf("Expected: %s\nGot: %s\n", CIPHER,
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(char *) cipher_tmp);
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free(key);
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return -1;
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}
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_mcrypt_decrypt(key, (void *) ciphertext);
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free(key);
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if (strcmp(ciphertext, plaintext) != 0) {
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printf("failed internally\n");
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return -1;
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}
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return 0;
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}
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WIN32DLL_DEFINE word32 _mcrypt_algorithm_version()
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{
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return 20010801;
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}
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#ifdef WIN32
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# ifdef USE_LTDL
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WIN32DLL_DEFINE int main (void)
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{
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/* empty main function to avoid linker error (see cygwin FAQ) */
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}
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# endif
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#endif
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