text: /* 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://libtom.org
   */
  #include "tomcrypt.h"
  
  /**
    @file f8_encrypt.c
    F8 implementation, encrypt data, Tom St Denis
  */
  
  #ifdef LTC_F8_MODE
  
  /**
    F8 encrypt
    @param pt     Plaintext
    @param ct     [out] Ciphertext
    @param len    Length of plaintext (octets)
    @param f8     F8 state
    @return CRYPT_OK if successful
  */
  int f8_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_F8 *f8)
  {
     int           err, x;
     unsigned char buf[MAXBLOCKSIZE];
     LTC_ARGCHK(pt != NULL);
     LTC_ARGCHK(ct != NULL);
     LTC_ARGCHK(f8 != NULL);
     if ((err = cipher_is_valid(f8->cipher)) != CRYPT_OK) {
         return err;
     }
     
     /* is blocklen/padlen valid? */
     if (f8->blocklen < 0 || f8->blocklen > (int)sizeof(f8->IV) ||
         f8->padlen   < 0 || f8->padlen   > (int)sizeof(f8->IV)) {
        return CRYPT_INVALID_ARG;
     }
     
     zeromem(buf, sizeof(buf));
  
     /* make sure the pad is empty */
     if (f8->padlen == f8->blocklen) {
        /* xor of IV, MIV and blockcnt == what goes into cipher */
        STORE32H(f8->blockcnt, (buf+(f8->blocklen-4)));
        ++(f8->blockcnt);
        for (x = 0; x < f8->blocklen; x++) {
            f8->IV[x] ^= f8->MIV[x] ^ buf[x];
        }
        if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(f8->IV, f8->IV, &f8->key)) != CRYPT_OK) {
           return err;
        }
        f8->padlen = 0;
     }
  
  #ifdef LTC_FAST
     if (f8->padlen == 0) {
        while (len >= (unsigned long)f8->blocklen) {
           STORE32H(f8->blockcnt, (buf+(f8->blocklen-4)));
           ++(f8->blockcnt);
           for (x = 0; x < f8->blocklen; x += sizeof(LTC_FAST_TYPE)) {
               *((LTC_FAST_TYPE*)(&ct[x])) = *((LTC_FAST_TYPE*)(&pt[x])) ^ *((LTC_FAST_TYPE*)(&f8->IV[x]));
               *((LTC_FAST_TYPE*)(&f8->IV[x])) ^= *((LTC_FAST_TYPE*)(&f8->MIV[x])) ^ *((LTC_FAST_TYPE*)(&buf[x]));
           }
           if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(f8->IV, f8->IV, &f8->key)) != CRYPT_OK) {
              return err;
           }
           len -= x;
           pt  += x;
           ct  += x;
        }
     }
  #endif             
  
     while (len > 0) {
         if (f8->padlen == f8->blocklen) {
            /* xor of IV, MIV and blockcnt == what goes into cipher */
            STORE32H(f8->blockcnt, (buf+(f8->blocklen-4)));
            ++(f8->blockcnt);
            for (x = 0; x < f8->blocklen; x++) {
                f8->IV[x] ^= f8->MIV[x] ^ buf[x];
            }
            if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(f8->IV, f8->IV, &f8->key)) != CRYPT_OK) {
               return err;
            }
            f8->padlen = 0;
         }
         *ct++ = *pt++ ^ f8->IV[f8->padlen++];
         --len;
     }
     return CRYPT_OK;
  }
  
  #endif
  
  /* $Source$ */
  /* $Revision$ */
  /* $Date$ */
  