/* 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. */ /**********************************************************************\ * 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 with fixed effective key length of 64bits */ #ifdef LTC_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, 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 bits The effective key length in bits @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_ex(const unsigned char *key, int keylen, int bits, int num_rounds, symmetric_key *skey) { unsigned *xkey = skey->rc2.xkey; unsigned char tmp[128]; unsigned T8, TM; int i; LTC_ARGCHK(key != NULL); LTC_ARGCHK(skey != NULL); if (keylen == 0 || keylen > 128 || bits > 1024) { return CRYPT_INVALID_KEYSIZE; } if (bits == 0) { bits = 1024; } 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" */ 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; } /** Initialize the RC2 block cipher The effective key length is here always keylen * 8 @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) { return rc2_setup_ex(key, keylen, keylen * 8, num_rounds, skey); } /**********************************************************************\ * 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, bits; unsigned char key[16], pt[8], ct[8]; } tests[] = { { 8, 63, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0xeb, 0xb7, 0x73, 0xf9, 0x93, 0x27, 0x8e, 0xff } }, { 8, 64, { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }, { 0x27, 0x8b, 0x27, 0xe4, 0x2e, 0x2f, 0x0d, 0x49 } }, { 8, 64, { 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 } }, { 1, 64, { 0x88, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x61, 0xa8, 0xa2, 0x44, 0xad, 0xac, 0xcc, 0xf0 } }, { 7, 64, { 0x88, 0xbc, 0xa9, 0x0e, 0x90, 0x87, 0x5a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x6c, 0xcf, 0x43, 0x08, 0x97, 0x4c, 0x26, 0x7f } }, { 16, 64, { 0x88, 0xbc, 0xa9, 0x0e, 0x90, 0x87, 0x5a, 0x7f, 0x0f, 0x79, 0xc3, 0x84, 0x62, 0x7b, 0xaf, 0xb2 }, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x1a, 0x80, 0x7d, 0x27, 0x2b, 0xbe, 0x5d, 0xb1 } }, { 16, 128, { 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 (tests[x].bits == (tests[x].keylen * 8)) { if ((err = rc2_setup(tests[x].key, tests[x].keylen, 0, &skey)) != CRYPT_OK) { return err; } } else { if ((err = rc2_setup_ex(tests[x].key, tests[x].keylen, tests[x].bits, 0, &skey)) != CRYPT_OK) { return err; } } rc2_ecb_encrypt(tests[x].pt, tmp[0], &skey); rc2_ecb_decrypt(tmp[0], tmp[1], &skey); if (compare_testvector(tmp[0], 8, tests[x].ct, 8, "RC2 CT", x) || compare_testvector(tmp[1], 8, tests[x].pt, 8, "RC2 PT", x)) { 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) { LTC_UNUSED_PARAM(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 < 1) { return CRYPT_INVALID_KEYSIZE; } else if (*keysize > 128) { *keysize = 128; } return CRYPT_OK; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */