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      1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
      2  *
      3  * LibTomCrypt is a library that provides various cryptographic
      4  * algorithms in a highly modular and flexible manner.
      5  *
      6  * The library is free for all purposes without any express
      7  * guarantee it works.
      8  *
      9  * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com
     10  */
     11 #include "tomcrypt.h"
     12 
     13 /**
     14    @file cbc_encrypt.c
     15    CBC implementation, encrypt block, Tom St Denis
     16 */
     17 
     18 
     19 #ifdef LTC_CBC_MODE
     20 
     21 /**
     22   CBC encrypt
     23   @param pt     Plaintext
     24   @param ct     [out] Ciphertext
     25   @param len    The number of bytes to process (must be multiple of block length)
     26   @param cbc    CBC state
     27   @return CRYPT_OK if successful
     28 */
     29 int cbc_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CBC *cbc)
     30 {
     31    int x, err;
     32 
     33    LTC_ARGCHK(pt != NULL);
     34    LTC_ARGCHK(ct != NULL);
     35    LTC_ARGCHK(cbc != NULL);
     36 
     37    if ((err = cipher_is_valid(cbc->cipher)) != CRYPT_OK) {
     38        return err;
     39    }
     40 
     41    /* is blocklen valid? */
     42    if (cbc->blocklen < 1 || cbc->blocklen > (int)sizeof(cbc->IV)) {
     43       return CRYPT_INVALID_ARG;
     44    }
     45 
     46    if (len % cbc->blocklen) {
     47       return CRYPT_INVALID_ARG;
     48    }
     49 #ifdef LTC_FAST
     50    if (cbc->blocklen % sizeof(LTC_FAST_TYPE)) {
     51       return CRYPT_INVALID_ARG;
     52    }
     53 #endif
     54 
     55    if (cipher_descriptor[cbc->cipher].accel_cbc_encrypt != NULL) {
     56       return cipher_descriptor[cbc->cipher].accel_cbc_encrypt(pt, ct, len / cbc->blocklen, cbc->IV, &cbc->key);
     57    } else {
     58       while (len) {
     59          /* xor IV against plaintext */
     60          #if defined(LTC_FAST)
     61         for (x = 0; x < cbc->blocklen; x += sizeof(LTC_FAST_TYPE)) {
     62             *((LTC_FAST_TYPE*)((unsigned char *)cbc->IV + x)) ^= *((LTC_FAST_TYPE*)((unsigned char *)pt + x));
     63         }
     64     #else
     65             for (x = 0; x < cbc->blocklen; x++) {
     66                cbc->IV[x] ^= pt[x];
     67             }
     68     #endif
     69 
     70          /* encrypt */
     71          if ((err = cipher_descriptor[cbc->cipher].ecb_encrypt(cbc->IV, ct, &cbc->key)) != CRYPT_OK) {
     72             return err;
     73          }
     74 
     75         /* store IV [ciphertext] for a future block */
     76          #if defined(LTC_FAST)
     77         for (x = 0; x < cbc->blocklen; x += sizeof(LTC_FAST_TYPE)) {
     78             *((LTC_FAST_TYPE*)((unsigned char *)cbc->IV + x)) = *((LTC_FAST_TYPE*)((unsigned char *)ct + x));
     79         }
     80     #else
     81              for (x = 0; x < cbc->blocklen; x++) {
     82                 cbc->IV[x] = ct[x];
     83              }
     84     #endif
     85 
     86         ct  += cbc->blocklen;
     87         pt  += cbc->blocklen;
     88         len -= cbc->blocklen;
     89      }
     90    }
     91    return CRYPT_OK;
     92 }
     93 
     94 #endif
     95 
     96 /* $Source: /cvs/libtom/libtomcrypt/src/modes/cbc/cbc_encrypt.c,v $ */
     97 /* $Revision: 1.13 $ */
     98 /* $Date: 2006/11/21 00:18:23 $ */
     99