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Diffstat (limited to 'libtomcrypt/src/ciphers/rc2.c')
| -rw-r--r-- | libtomcrypt/src/ciphers/rc2.c | 362 |
1 files changed, 362 insertions, 0 deletions
diff --git a/libtomcrypt/src/ciphers/rc2.c b/libtomcrypt/src/ciphers/rc2.c new file mode 100644 index 0000000..de62cda --- /dev/null +++ b/libtomcrypt/src/ciphers/rc2.c @@ -0,0 +1,362 @@ +/* LibTomCrypt, modular cryptographic library -- Tom St Denis + * + * LibTomCrypt is a library that provides various cryptographic + * algorithms in a highly modular and flexible manner. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com + */ +/**********************************************************************\ +* To commemorate the 1996 RSA Data Security Conference, the following * +* code is released into the public domain by its author. Prost! * +* * +* This cipher uses 16-bit words and little-endian byte ordering. * +* I wonder which processor it was optimized for? * +* * +* Thanks to CodeView, SoftIce, and D86 for helping bring this code to * +* the public. * +\**********************************************************************/ +#include <tomcrypt.h> + +/** + @file rc2.c + Implementation of RC2 +*/ + +#ifdef RC2 + +const struct ltc_cipher_descriptor rc2_desc = { + "rc2", + 12, 8, 128, 8, 16, + &rc2_setup, + &rc2_ecb_encrypt, + &rc2_ecb_decrypt, + &rc2_test, + &rc2_done, + &rc2_keysize, + NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL +}; + +/* 256-entry permutation table, probably derived somehow from pi */ +static const unsigned char permute[256] = { + 217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157, + 198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162, + 23,154, 89,245,135,179, 79, 19, 97, 69,109,141, 9,129,125, 50, + 189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130, + 84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220, + 18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38, + 111,191, 14,218, 70,105, 7, 87, 39,242, 29,155,188,148, 67, 3, + 248, 17,199,246,144,239, 62,231, 6,195,213, 47,200,102, 30,215, + 8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42, + 150, 26,210,113, 90, 21, 73,116, 75,159,208, 94, 4, 24,164,236, + 194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57, + 153,124, 58,133, 35,184,180,122,252, 2, 54, 91, 37, 85,151, 49, + 45, 93,250,152,227,138,146,174, 5,223, 41, 16,103,108,186,201, + 211, 0,230,207,225,158,168, 44, 99, 22, 1, 63, 88,226,137,169, + 13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46, + 197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173 +}; + + /** + Initialize the RC2 block cipher + @param key The symmetric key you wish to pass + @param keylen The key length in bytes + @param num_rounds The number of rounds desired (0 for default) + @param skey The key in as scheduled by this function. + @return CRYPT_OK if successful + */ +int rc2_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) +{ + unsigned *xkey = skey->rc2.xkey; + unsigned char tmp[128]; + unsigned T8, TM; + int i, bits; + + LTC_ARGCHK(key != NULL); + LTC_ARGCHK(skey != NULL); + + if (keylen < 8 || keylen > 128) { + return CRYPT_INVALID_KEYSIZE; + } + + if (num_rounds != 0 && num_rounds != 16) { + return CRYPT_INVALID_ROUNDS; + } + + for (i = 0; i < keylen; i++) { + tmp[i] = key[i] & 255; + } + + /* Phase 1: Expand input key to 128 bytes */ + if (keylen < 128) { + for (i = keylen; i < 128; i++) { + tmp[i] = permute[(tmp[i - 1] + tmp[i - keylen]) & 255]; + } + } + + /* Phase 2 - reduce effective key size to "bits" */ + bits = keylen<<3; + T8 = (unsigned)(bits+7)>>3; + TM = (255 >> (unsigned)(7 & -bits)); + tmp[128 - T8] = permute[tmp[128 - T8] & TM]; + for (i = 127 - T8; i >= 0; i--) { + tmp[i] = permute[tmp[i + 1] ^ tmp[i + T8]]; + } + + /* Phase 3 - copy to xkey in little-endian order */ + for (i = 0; i < 64; i++) { + xkey[i] = (unsigned)tmp[2*i] + ((unsigned)tmp[2*i+1] << 8); + } + +#ifdef LTC_CLEAN_STACK + zeromem(tmp, sizeof(tmp)); +#endif + + return CRYPT_OK; +} + +/**********************************************************************\ +* Encrypt an 8-byte block of plaintext using the given key. * +\**********************************************************************/ +/** + Encrypts a block of text with RC2 + @param pt The input plaintext (8 bytes) + @param ct The output ciphertext (8 bytes) + @param skey The key as scheduled + @return CRYPT_OK if successful +*/ +#ifdef LTC_CLEAN_STACK +static int _rc2_ecb_encrypt( const unsigned char *pt, + unsigned char *ct, + symmetric_key *skey) +#else +int rc2_ecb_encrypt( const unsigned char *pt, + unsigned char *ct, + symmetric_key *skey) +#endif +{ + unsigned *xkey; + unsigned x76, x54, x32, x10, i; + + LTC_ARGCHK(pt != NULL); + LTC_ARGCHK(ct != NULL); + LTC_ARGCHK(skey != NULL); + + xkey = skey->rc2.xkey; + + x76 = ((unsigned)pt[7] << 8) + (unsigned)pt[6]; + x54 = ((unsigned)pt[5] << 8) + (unsigned)pt[4]; + x32 = ((unsigned)pt[3] << 8) + (unsigned)pt[2]; + x10 = ((unsigned)pt[1] << 8) + (unsigned)pt[0]; + + for (i = 0; i < 16; i++) { + x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4*i+0]) & 0xFFFF; + x10 = ((x10 << 1) | (x10 >> 15)); + + x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4*i+1]) & 0xFFFF; + x32 = ((x32 << 2) | (x32 >> 14)); + + x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4*i+2]) & 0xFFFF; + x54 = ((x54 << 3) | (x54 >> 13)); + + x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4*i+3]) & 0xFFFF; + x76 = ((x76 << 5) | (x76 >> 11)); + + if (i == 4 || i == 10) { + x10 = (x10 + xkey[x76 & 63]) & 0xFFFF; + x32 = (x32 + xkey[x10 & 63]) & 0xFFFF; + x54 = (x54 + xkey[x32 & 63]) & 0xFFFF; + x76 = (x76 + xkey[x54 & 63]) & 0xFFFF; + } + } + + ct[0] = (unsigned char)x10; + ct[1] = (unsigned char)(x10 >> 8); + ct[2] = (unsigned char)x32; + ct[3] = (unsigned char)(x32 >> 8); + ct[4] = (unsigned char)x54; + ct[5] = (unsigned char)(x54 >> 8); + ct[6] = (unsigned char)x76; + ct[7] = (unsigned char)(x76 >> 8); + + return CRYPT_OK; +} + +#ifdef LTC_CLEAN_STACK +int rc2_ecb_encrypt( const unsigned char *pt, + unsigned char *ct, + symmetric_key *skey) +{ + int err = _rc2_ecb_encrypt(pt, ct, skey); + burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 5); + return err; +} +#endif + +/**********************************************************************\ +* Decrypt an 8-byte block of ciphertext using the given key. * +\**********************************************************************/ +/** + Decrypts a block of text with RC2 + @param ct The input ciphertext (8 bytes) + @param pt The output plaintext (8 bytes) + @param skey The key as scheduled + @return CRYPT_OK if successful +*/ +#ifdef LTC_CLEAN_STACK +static int _rc2_ecb_decrypt( const unsigned char *ct, + unsigned char *pt, + symmetric_key *skey) +#else +int rc2_ecb_decrypt( const unsigned char *ct, + unsigned char *pt, + symmetric_key *skey) +#endif +{ + unsigned x76, x54, x32, x10; + unsigned *xkey; + int i; + + LTC_ARGCHK(pt != NULL); + LTC_ARGCHK(ct != NULL); + LTC_ARGCHK(skey != NULL); + + xkey = skey->rc2.xkey; + + x76 = ((unsigned)ct[7] << 8) + (unsigned)ct[6]; + x54 = ((unsigned)ct[5] << 8) + (unsigned)ct[4]; + x32 = ((unsigned)ct[3] << 8) + (unsigned)ct[2]; + x10 = ((unsigned)ct[1] << 8) + (unsigned)ct[0]; + + for (i = 15; i >= 0; i--) { + if (i == 4 || i == 10) { + x76 = (x76 - xkey[x54 & 63]) & 0xFFFF; + x54 = (x54 - xkey[x32 & 63]) & 0xFFFF; + x32 = (x32 - xkey[x10 & 63]) & 0xFFFF; + x10 = (x10 - xkey[x76 & 63]) & 0xFFFF; + } + + x76 = ((x76 << 11) | (x76 >> 5)); + x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4*i+3])) & 0xFFFF; + + x54 = ((x54 << 13) | (x54 >> 3)); + x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4*i+2])) & 0xFFFF; + + x32 = ((x32 << 14) | (x32 >> 2)); + x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4*i+1])) & 0xFFFF; + + x10 = ((x10 << 15) | (x10 >> 1)); + x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4*i+0])) & 0xFFFF; + } + + pt[0] = (unsigned char)x10; + pt[1] = (unsigned char)(x10 >> 8); + pt[2] = (unsigned char)x32; + pt[3] = (unsigned char)(x32 >> 8); + pt[4] = (unsigned char)x54; + pt[5] = (unsigned char)(x54 >> 8); + pt[6] = (unsigned char)x76; + pt[7] = (unsigned char)(x76 >> 8); + + return CRYPT_OK; +} + +#ifdef LTC_CLEAN_STACK +int rc2_ecb_decrypt( const unsigned char *ct, + unsigned char *pt, + symmetric_key *skey) +{ + int err = _rc2_ecb_decrypt(ct, pt, skey); + burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 4 + sizeof(int)); + return err; +} +#endif + +/** + Performs a self-test of the RC2 block cipher + @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled +*/ +int rc2_test(void) +{ + #ifndef LTC_TEST + return CRYPT_NOP; + #else + static const struct { + int keylen; + unsigned char key[16], pt[8], ct[8]; + } tests[] = { + + { 8, + { 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, + { 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 }, + { 0x30, 0x64, 0x9e, 0xdf, 0x9b, 0xe7, 0xd2, 0xc2 } + + }, + { 16, + { 0x88, 0xbc, 0xa9, 0x0e, 0x90, 0x87, 0x5a, 0x7f, + 0x0f, 0x79, 0xc3, 0x84, 0x62, 0x7b, 0xaf, 0xb2 }, + { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, + { 0x22, 0x69, 0x55, 0x2a, 0xb0, 0xf8, 0x5c, 0xa6 } + } + }; + int x, y, err; + symmetric_key skey; + unsigned char tmp[2][8]; + + for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) { + zeromem(tmp, sizeof(tmp)); + if ((err = rc2_setup(tests[x].key, tests[x].keylen, 0, &skey)) != CRYPT_OK) { + return err; + } + + rc2_ecb_encrypt(tests[x].pt, tmp[0], &skey); + rc2_ecb_decrypt(tmp[0], tmp[1], &skey); + + if (XMEMCMP(tmp[0], tests[x].ct, 8) != 0 || XMEMCMP(tmp[1], tests[x].pt, 8) != 0) { + return CRYPT_FAIL_TESTVECTOR; + } + + /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */ + for (y = 0; y < 8; y++) tmp[0][y] = 0; + for (y = 0; y < 1000; y++) rc2_ecb_encrypt(tmp[0], tmp[0], &skey); + for (y = 0; y < 1000; y++) rc2_ecb_decrypt(tmp[0], tmp[0], &skey); + for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR; + } + return CRYPT_OK; + #endif +} + +/** Terminate the context + @param skey The scheduled key +*/ +void rc2_done(symmetric_key *skey) +{ +} + +/** + Gets suitable key size + @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable. + @return CRYPT_OK if the input key size is acceptable. +*/ +int rc2_keysize(int *keysize) +{ + LTC_ARGCHK(keysize != NULL); + if (*keysize < 8) { + return CRYPT_INVALID_KEYSIZE; + } else if (*keysize > 128) { + *keysize = 128; + } + return CRYPT_OK; +} + +#endif + + + + +/* $Source: /cvs/libtom/libtomcrypt/src/ciphers/rc2.c,v $ */ +/* $Revision: 1.12 $ */ +/* $Date: 2006/11/08 23:01:06 $ */ |