/* 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.com */#include "tomcrypt.h"/**   @file lrw_process.c   LRW_MODE implementation, Encrypt/decrypt blocks, Tom St Denis*/#ifdef LTC_LRW_MODE/**  Process blocks with LRW, since decrypt/encrypt are largely the same they share this code.  @param pt        The "input" data  @param ct        [out] The "output" data  @param len       The length of the input, must be a multiple of 128-bits (16 octets)  @param mode      LRW_ENCRYPT or LRW_DECRYPT  @param lrw       The LRW state  @return  CRYPT_OK if successful*/int lrw_process(const unsigned char *pt, unsigned char *ct, unsigned long len, int mode, symmetric_LRW *lrw){   unsigned char prod[16];   int           x, err;#ifdef LRW_TABLES   int           y;#endif   LTC_ARGCHK(pt  != NULL);   LTC_ARGCHK(ct  != NULL);   LTC_ARGCHK(lrw != NULL);   if (len & 15) {      return CRYPT_INVALID_ARG;   }   while (len) {      /* copy pad */      XMEMCPY(prod, lrw->pad, 16);      /* increment IV */      for (x = 15; x >= 0; x--) {          lrw->IV[x] = (lrw->IV[x] + 1) & 255;          if (lrw->IV[x]) {               break;          }      }      /* update pad */#ifdef LRW_TABLES      /* for each byte changed we undo it's affect on the pad then add the new product */      for (; x < 16; x++) {#ifdef LTC_FAST          for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {              *((LTC_FAST_TYPE *)(lrw->pad + y)) ^= *((LTC_FAST_TYPE *)(&lrw->PC[x][lrw->IV[x]][y])) ^ *((LTC_FAST_TYPE *)(&lrw->PC[x][(lrw->IV[x]-1)&255][y]));          }#else          for (y = 0; y < 16; y++) {              lrw->pad[y] ^= lrw->PC[x][lrw->IV[x]][y] ^ lrw->PC[x][(lrw->IV[x]-1)&255][y];          }#endif      }#else      gcm_gf_mult(lrw->tweak, lrw->IV, lrw->pad);#endif      /* xor prod */#ifdef LTC_FAST      for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {           *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(pt + x)) ^ *((LTC_FAST_TYPE *)(prod + x));      }#else      for (x = 0; x < 16; x++) {         ct[x] = pt[x] ^ prod[x];      }#endif      /* send through cipher */      if (mode == LRW_ENCRYPT) {         if ((err = cipher_descriptor[lrw->cipher].ecb_encrypt(ct, ct, &lrw->key)) != CRYPT_OK) {            return err;         }      } else {         if ((err = cipher_descriptor[lrw->cipher].ecb_decrypt(ct, ct, &lrw->key)) != CRYPT_OK) {            return err;         }      }                     /* xor prod */#ifdef LTC_FAST      for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {           *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(ct + x)) ^ *((LTC_FAST_TYPE *)(prod + x));      }#else      for (x = 0; x < 16; x++) {         ct[x] = ct[x] ^ prod[x];      }#endif         /* move to next */      pt  += 16;      ct  += 16;      len -= 16;   }   return CRYPT_OK;}      #endif/* $Source: /cvs/libtom/libtomcrypt/src/modes/lrw/lrw_process.c,v $ *//* $Revision: 1.10 $ *//* $Date: 2006/06/29 01:53:13 $ */