/* 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 */#include <tomcrypt.h>/**    @file pkcs_5_2.c   PKCS #5, Algorithm #2, Tom St Denis*/#ifdef PKCS_5/**   Execute PKCS #5 v2   @param password          The input password (or key)   @param password_len      The length of the password (octets)   @param salt              The salt (or nonce)   @param salt_len          The length of the salt (octets)   @param iteration_count   # of iterations desired for PKCS #5 v2 [read specs for more]   @param hash_idx          The index of the hash desired   @param out               [out] The destination for this algorithm   @param outlen            [in/out] The max size and resulting size of the algorithm output   @return CRYPT_OK if successful*/int pkcs_5_alg2(const unsigned char *password, unsigned long password_len,                 const unsigned char *salt,     unsigned long salt_len,                int iteration_count,           int hash_idx,                unsigned char *out,            unsigned long *outlen){   int err, itts;   ulong32  blkno;   unsigned long stored, left, x, y;   unsigned char *buf[2];   hmac_state    *hmac;   LTC_ARGCHK(password != NULL);   LTC_ARGCHK(salt     != NULL);   LTC_ARGCHK(out      != NULL);   LTC_ARGCHK(outlen   != NULL);   /* test hash IDX */   if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {      return err;   }   buf[0] = XMALLOC(MAXBLOCKSIZE * 2);   hmac   = XMALLOC(sizeof(hmac_state));   if (hmac == NULL || buf[0] == NULL) {      if (hmac != NULL) {         XFREE(hmac);      }      if (buf[0] != NULL) {         XFREE(buf[0]);      }      return CRYPT_MEM;   }   /* buf[1] points to the second block of MAXBLOCKSIZE bytes */   buf[1] = buf[0] + MAXBLOCKSIZE;   left   = *outlen;   blkno  = 1;   stored = 0;   while (left != 0) {       /* process block number blkno */       zeromem(buf[0], MAXBLOCKSIZE*2);              /* store current block number and increment for next pass */       STORE32H(blkno, buf[1]);       ++blkno;       /* get PRF(P, S||int(blkno)) */       if ((err = hmac_init(hmac, hash_idx, password, password_len)) != CRYPT_OK) {           goto LBL_ERR;       }       if ((err = hmac_process(hmac, salt, salt_len)) != CRYPT_OK) {          goto LBL_ERR;       }       if ((err = hmac_process(hmac, buf[1], 4)) != CRYPT_OK) {          goto LBL_ERR;       }       x = MAXBLOCKSIZE;       if ((err = hmac_done(hmac, buf[0], &x)) != CRYPT_OK) {          goto LBL_ERR;       }       /* now compute repeated and XOR it in buf[1] */       XMEMCPY(buf[1], buf[0], x);       for (itts = 1; itts < iteration_count; ++itts) {           if ((err = hmac_memory(hash_idx, password, password_len, buf[0], x, buf[0], &x)) != CRYPT_OK) {              goto LBL_ERR;           }           for (y = 0; y < x; y++) {               buf[1][y] ^= buf[0][y];           }       }       /* now emit upto x bytes of buf[1] to output */       for (y = 0; y < x && left != 0; ++y) {           out[stored++] = buf[1][y];           --left;       }   }   *outlen = stored;   err = CRYPT_OK;LBL_ERR:#ifdef LTC_CLEAN_STACK   zeromem(buf[0], MAXBLOCKSIZE*2);   zeromem(hmac, sizeof(hmac_state));#endif   XFREE(hmac);   XFREE(buf[0]);   return err;}#endif/* $Source: /cvs/libtom/libtomcrypt/src/misc/pkcs5/pkcs_5_2.c,v $ *//* $Revision: 1.4 $ *//* $Date: 2005/05/05 14:35:59 $ */