/* 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@iahu.ca, http://libtomcrypt.org *//* RC6 code by Tom St Denis */#include "mycrypt.h"#ifdef RC6const struct _cipher_descriptor rc6_desc ={    "rc6",    3,    8, 128, 16, 20,    &rc6_setup,    &rc6_ecb_encrypt,    &rc6_ecb_decrypt,    &rc6_test,    &rc6_keysize};static const ulong32 stab[44] = {0xb7e15163UL, 0x5618cb1cUL, 0xf45044d5UL, 0x9287be8eUL, 0x30bf3847UL, 0xcef6b200UL, 0x6d2e2bb9UL, 0x0b65a572UL,0xa99d1f2bUL, 0x47d498e4UL, 0xe60c129dUL, 0x84438c56UL, 0x227b060fUL, 0xc0b27fc8UL, 0x5ee9f981UL, 0xfd21733aUL,0x9b58ecf3UL, 0x399066acUL, 0xd7c7e065UL, 0x75ff5a1eUL, 0x1436d3d7UL, 0xb26e4d90UL, 0x50a5c749UL, 0xeedd4102UL,0x8d14babbUL, 0x2b4c3474UL, 0xc983ae2dUL, 0x67bb27e6UL, 0x05f2a19fUL, 0xa42a1b58UL, 0x42619511UL, 0xe0990ecaUL,0x7ed08883UL, 0x1d08023cUL, 0xbb3f7bf5UL, 0x5976f5aeUL, 0xf7ae6f67UL, 0x95e5e920UL, 0x341d62d9UL, 0xd254dc92UL,0x708c564bUL, 0x0ec3d004UL, 0xacfb49bdUL, 0x4b32c376UL };#ifdef CLEAN_STACKstatic int _rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)#elseint rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)#endif{    ulong32 L[64], S[50], A, B, i, j, v, s, l;    _ARGCHK(key != NULL);    _ARGCHK(skey != NULL);    /* test parameters */    if (num_rounds != 0 && num_rounds != 20) {        return CRYPT_INVALID_ROUNDS;    }    /* key must be between 64 and 1024 bits */    if (keylen < 8 || keylen > 128) {       return CRYPT_INVALID_KEYSIZE;    }    /* copy the key into the L array */    for (A = i = j = 0; i < (ulong32)keylen; ) {         A = (A << 8) | ((ulong32)(key[i++] & 255));        if (!(i & 3)) {           L[j++] = BSWAP(A);           A = 0;        }    }    /* handle odd sized keys */    if (keylen & 3) {        A <<= (8 * (4 - (keylen&3)));        L[j++] = BSWAP(A);     }    /* setup the S array */    memcpy(S, stab, 44 * sizeof(stab[0]));    /* mix buffer */    s = 3 * MAX(44, j);    l = j;    for (A = B = i = j = v = 0; v < s; v++) {         A = S[i] = ROL(S[i] + A + B, 3);        B = L[j] = ROL(L[j] + A + B, (A+B));        if (++i == 44) { i = 0; }        if (++j == l)  { j = 0; }    }        /* copy to key */    for (i = 0; i < 44; i++) {         skey->rc6.K[i] = S[i];    }    return CRYPT_OK;}#ifdef CLEAN_STACKint rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey){   int x;   x = _rc6_setup(key, keylen, num_rounds, skey);   burn_stack(sizeof(ulong32) * 122);   return x;}#endif#ifdef CLEAN_STACKstatic void _rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)#elsevoid rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)#endif{   ulong32 a,b,c,d,t,u, *K;   int r;      _ARGCHK(key != NULL);   _ARGCHK(pt != NULL);   _ARGCHK(ct != NULL);   LOAD32L(a,&pt[0]);LOAD32L(b,&pt[4]);LOAD32L(c,&pt[8]);LOAD32L(d,&pt[12]);   b += key->rc6.K[0];   d += key->rc6.K[1];#define RND(a,b,c,d) \       t = (b * (b + b + 1)); t = ROL(t, 5); \       u = (d * (d + d + 1)); u = ROL(u, 5); \       a = ROL(a^t,u) + K[0];                \       c = ROL(c^u,t) + K[1]; K += 2;          K = key->rc6.K + 2;   for (r = 0; r < 20; r += 4) {       RND(a,b,c,d);       RND(b,c,d,a);       RND(c,d,a,b);       RND(d,a,b,c);   }   #undef RND   a += key->rc6.K[42];   c += key->rc6.K[43];   STORE32L(a,&ct[0]);STORE32L(b,&ct[4]);STORE32L(c,&ct[8]);STORE32L(d,&ct[12]);}#ifdef CLEAN_STACKvoid rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key){   _rc6_ecb_encrypt(pt, ct, key);   burn_stack(sizeof(ulong32) * 6 + sizeof(int));}#endif#ifdef CLEAN_STACKstatic void _rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)#elsevoid rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)#endif{   ulong32 a,b,c,d,t,u, *K;   int r;   _ARGCHK(key != NULL);   _ARGCHK(pt != NULL);   _ARGCHK(ct != NULL);      LOAD32L(a,&ct[0]);LOAD32L(b,&ct[4]);LOAD32L(c,&ct[8]);LOAD32L(d,&ct[12]);   a -= key->rc6.K[42];   c -= key->rc6.K[43];   #define RND(a,b,c,d) \       t = (b * (b + b + 1)); t = ROL(t, 5); \       u = (d * (d + d + 1)); u = ROL(u, 5); \       c = ROR(c - K[1], t) ^ u; \       a = ROR(a - K[0], u) ^ t; K -= 2;      K = key->rc6.K + 40;      for (r = 0; r < 20; r += 4) {       RND(d,a,b,c);       RND(c,d,a,b);       RND(b,c,d,a);       RND(a,b,c,d);   }   #undef RND   b -= key->rc6.K[0];   d -= key->rc6.K[1];   STORE32L(a,&pt[0]);STORE32L(b,&pt[4]);STORE32L(c,&pt[8]);STORE32L(d,&pt[12]);}#ifdef CLEAN_STACKvoid rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key){   _rc6_ecb_decrypt(ct, pt, key);   burn_stack(sizeof(ulong32) * 6 + sizeof(int));}#endifint rc6_test(void){ #ifndef LTC_TEST    return CRYPT_NOP; #else       static const struct {       int keylen;       unsigned char key[32], pt[16], ct[16];   } tests[] = {   {       16,       { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,         0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },       { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,         0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },       { 0x52, 0x4e, 0x19, 0x2f, 0x47, 0x15, 0xc6, 0x23,         0x1f, 0x51, 0xf6, 0x36, 0x7e, 0xa4, 0x3f, 0x18 }   },   {       24,       { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,         0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,         0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },       { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,         0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },       { 0x68, 0x83, 0x29, 0xd0, 0x19, 0xe5, 0x05, 0x04,         0x1e, 0x52, 0xe9, 0x2a, 0xf9, 0x52, 0x91, 0xd4 }   },   {       32,       { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,         0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,         0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,         0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe },       { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,         0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },       { 0xc8, 0x24, 0x18, 0x16, 0xf0, 0xd7, 0xe4, 0x89,         0x20, 0xad, 0x16, 0xa1, 0x67, 0x4e, 0x5d, 0x48 }   }   };   unsigned char tmp[2][16];   int x, y, err;   symmetric_key key;   for (x  = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {      /* setup key */      if ((err = rc6_setup(tests[x].key, tests[x].keylen, 0, &key)) != CRYPT_OK) {         return err;      }      /* encrypt and decrypt */      rc6_ecb_encrypt(tests[x].pt, tmp[0], &key);      rc6_ecb_decrypt(tmp[0], tmp[1], &key);      /* compare */      if (memcmp(tmp[0], tests[x].ct, 16) || memcmp(tmp[1], tests[x].pt, 16)) {#if 0         printf("\n\nFailed test %d\n", x);         if (memcmp(tmp[0], tests[x].ct, 16)) {            printf("Ciphertext:  ");            for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);            printf("\nExpected  :  ");            for (y = 0; y < 16; y++) printf("%02x ", tests[x].ct[y]);            printf("\n");         }         if (memcmp(tmp[1], tests[x].pt, 16)) {            printf("Plaintext:  ");            for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);            printf("\nExpected :  ");            for (y = 0; y < 16; y++) printf("%02x ", tests[x].pt[y]);            printf("\n");         }#endif         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 < 16; y++) tmp[0][y] = 0;      for (y = 0; y < 1000; y++) rc6_ecb_encrypt(tmp[0], tmp[0], &key);      for (y = 0; y < 1000; y++) rc6_ecb_decrypt(tmp[0], tmp[0], &key);      for (y = 0; y < 16; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;   }   return CRYPT_OK;  #endif}int rc6_keysize(int *desired_keysize){   _ARGCHK(desired_keysize != NULL);   if (*desired_keysize < 8) {      return CRYPT_INVALID_KEYSIZE;   } else if (*desired_keysize > 128) {      *desired_keysize = 128;   }   return CRYPT_OK;}#endif /*RC6*/