/* 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.org *//**   @file rc5.c   RC5 code by Tom St Denis */#include "tomcrypt.h"#ifdef RC5const struct ltc_cipher_descriptor rc5_desc ={    "rc5",    2,    8, 128, 8, 12,    &rc5_setup,    &rc5_ecb_encrypt,    &rc5_ecb_decrypt,    &rc5_test,    &rc5_done,    &rc5_keysize,    NULL, NULL, NULL, NULL, NULL, NULL, NULL};static const ulong32 stab[50] = {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, 0xe96a3d2fUL, 0x87a1b6e8UL, 0x25d930a1UL, 0xc410aa5aUL,0x62482413UL, 0x007f9dccUL}; /**    Initialize the RC5 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 */#ifdef LTC_CLEAN_STACKstatic int _rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)#elseint rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)#endif{    ulong32 L[64], *S, A, B, i, j, v, s, t, l;    LTC_ARGCHK(skey != NULL);    LTC_ARGCHK(key  != NULL);        /* test parameters */    if (num_rounds == 0) {        num_rounds = rc5_desc.default_rounds;    }    if (num_rounds < 12 || num_rounds > 24) {        return CRYPT_INVALID_ROUNDS;    }    /* key must be between 64 and 1024 bits */    if (keylen < 8 || keylen > 128) {       return CRYPT_INVALID_KEYSIZE;    }        skey->rc5.rounds = num_rounds;    S = skey->rc5.K;    /* 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) == 0) {           L[j++] = BSWAP(A);           A = 0;        }    }    if ((keylen & 3) != 0) {        A <<= (ulong32)((8 * (4 - (keylen&3))));        L[j++] = BSWAP(A);    }    /* setup the S array */    t = (ulong32)(2 * (num_rounds + 1));    XMEMCPY(S, stab, t * sizeof(*S));    /* mix buffer */    s = 3 * MAX(t, j);    l = j;    for (A = B = i = j = v = 0; v < s; v++) {         A = S[i] = ROLc(S[i] + A + B, 3);        B = L[j] = ROL(L[j] + A + B, (A+B));        if (++i == t) { i = 0; }        if (++j == l) { j = 0; }    }    return CRYPT_OK;}#ifdef LTC_CLEAN_STACKint rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey){   int x;   x = _rc5_setup(key, keylen, num_rounds, skey);   burn_stack(sizeof(ulong32) * 122 + sizeof(int));   return x;}#endif/**  Encrypts a block of text with RC5  @param pt The input plaintext (8 bytes)  @param ct The output ciphertext (8 bytes)  @param skey The key as scheduled*/#ifdef LTC_CLEAN_STACKstatic void _rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)#elsevoid rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)#endif{   ulong32 A, B, *K;   int r;   LTC_ARGCHK(skey != NULL);   LTC_ARGCHK(pt   != NULL);   LTC_ARGCHK(ct   != NULL);   LOAD32L(A, &pt[0]);   LOAD32L(B, &pt[4]);   A += skey->rc5.K[0];   B += skey->rc5.K[1];   K  = skey->rc5.K + 2;      if ((skey->rc5.rounds & 1) == 0) {      for (r = 0; r < skey->rc5.rounds; r += 2) {          A = ROL(A ^ B, B) + K[0];          B = ROL(B ^ A, A) + K[1];          A = ROL(A ^ B, B) + K[2];          B = ROL(B ^ A, A) + K[3];          K += 4;      }   } else {      for (r = 0; r < skey->rc5.rounds; r++) {          A = ROL(A ^ B, B) + K[0];          B = ROL(B ^ A, A) + K[1];          K += 2;      }   }   STORE32L(A, &ct[0]);   STORE32L(B, &ct[4]);}#ifdef LTC_CLEAN_STACKvoid rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey){   _rc5_ecb_encrypt(pt, ct, skey);   burn_stack(sizeof(ulong32) * 2 + sizeof(int));}#endif/**  Decrypts a block of text with RC5  @param ct The input ciphertext (8 bytes)  @param pt The output plaintext (8 bytes)  @param skey The key as scheduled */#ifdef LTC_CLEAN_STACKstatic void _rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)#elsevoid rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)#endif{   ulong32 A, B, *K;   int r;   LTC_ARGCHK(skey != NULL);   LTC_ARGCHK(pt   != NULL);   LTC_ARGCHK(ct   != NULL);   LOAD32L(A, &ct[0]);   LOAD32L(B, &ct[4]);   K = skey->rc5.K + (skey->rc5.rounds << 1);      if ((skey->rc5.rounds & 1) == 0) {       K -= 2;       for (r = skey->rc5.rounds - 1; r >= 0; r -= 2) {          B = ROR(B - K[3], A) ^ A;          A = ROR(A - K[2], B) ^ B;          B = ROR(B - K[1], A) ^ A;          A = ROR(A - K[0], B) ^ B;          K -= 4;        }   } else {      for (r = skey->rc5.rounds - 1; r >= 0; r--) {          B = ROR(B - K[1], A) ^ A;          A = ROR(A - K[0], B) ^ B;          K -= 2;      }   }   A -= skey->rc5.K[0];   B -= skey->rc5.K[1];   STORE32L(A, &pt[0]);   STORE32L(B, &pt[4]);}#ifdef LTC_CLEAN_STACKvoid rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey){   _rc5_ecb_decrypt(ct, pt, skey);   burn_stack(sizeof(ulong32) * 2 + sizeof(int));}#endif/**  Performs a self-test of the RC5 block cipher  @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled*/int rc5_test(void){ #ifndef LTC_TEST    return CRYPT_NOP; #else       static const struct {       unsigned char key[16], pt[8], ct[8];   } tests[] = {   {       { 0x91, 0x5f, 0x46, 0x19, 0xbe, 0x41, 0xb2, 0x51,         0x63, 0x55, 0xa5, 0x01, 0x10, 0xa9, 0xce, 0x91 },       { 0x21, 0xa5, 0xdb, 0xee, 0x15, 0x4b, 0x8f, 0x6d },       { 0xf7, 0xc0, 0x13, 0xac, 0x5b, 0x2b, 0x89, 0x52 }   },   {       { 0x78, 0x33, 0x48, 0xe7, 0x5a, 0xeb, 0x0f, 0x2f,         0xd7, 0xb1, 0x69, 0xbb, 0x8d, 0xc1, 0x67, 0x87 },       { 0xF7, 0xC0, 0x13, 0xAC, 0x5B, 0x2B, 0x89, 0x52 },       { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 }   },   {       { 0xDC, 0x49, 0xdb, 0x13, 0x75, 0xa5, 0x58, 0x4f,         0x64, 0x85, 0xb4, 0x13, 0xb5, 0xf1, 0x2b, 0xaf },       { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 },       { 0x65, 0xc1, 0x78, 0xb2, 0x84, 0xd1, 0x97, 0xcc }   }   };   unsigned char tmp[2][8];   int x, y, err;   symmetric_key key;   for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {      /* setup key */      if ((err = rc5_setup(tests[x].key, 16, 12, &key)) != CRYPT_OK) {         return err;      }      /* encrypt and decrypt */      rc5_ecb_encrypt(tests[x].pt, tmp[0], &key);      rc5_ecb_decrypt(tmp[0], tmp[1], &key);      /* compare */      if (memcmp(tmp[0], tests[x].ct, 8) != 0 || memcmp(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++) rc5_ecb_encrypt(tmp[0], tmp[0], &key);      for (y = 0; y < 1000; y++) rc5_ecb_decrypt(tmp[0], tmp[0], &key);      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 rc5_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 rc5_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/rc5.c,v $ *//* $Revision: 1.7 $ *//* $Date: 2005/05/05 14:35:58 $ */