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@gmail.com, http://libtomcrypt.com
10 */
11#include "tomcrypt.h"
12
13/**
14  @file f8_encrypt.c
15  F8 implementation, encrypt data, Tom St Denis
16*/
17
18#ifdef LTC_F8_MODE
19
20/**
21  F8 encrypt
22  @param pt     Plaintext
23  @param ct     [out] Ciphertext
24  @param len    Length of plaintext (octets)
25  @param f8     F8 state
26  @return CRYPT_OK if successful
27*/
28int f8_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_F8 *f8)
29{
30   int           err, x;
31   unsigned char buf[MAXBLOCKSIZE];
32   LTC_ARGCHK(pt != NULL);
33   LTC_ARGCHK(ct != NULL);
34   LTC_ARGCHK(f8 != NULL);
35   if ((err = cipher_is_valid(f8->cipher)) != CRYPT_OK) {
36       return err;
37   }
38
39   /* is blocklen/padlen valid? */
40   if (f8->blocklen < 0 || f8->blocklen > (int)sizeof(f8->IV) ||
41       f8->padlen   < 0 || f8->padlen   > (int)sizeof(f8->IV)) {
42      return CRYPT_INVALID_ARG;
43   }
44
45   zeromem(buf, sizeof(buf));
46
47   /* make sure the pad is empty */
48   if (f8->padlen == f8->blocklen) {
49      /* xor of IV, MIV and blockcnt == what goes into cipher */
50      STORE32H(f8->blockcnt, (buf+(f8->blocklen-4)));
51      ++(f8->blockcnt);
52      for (x = 0; x < f8->blocklen; x++) {
53          f8->IV[x] ^= f8->MIV[x] ^ buf[x];
54      }
55      if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(f8->IV, f8->IV, &f8->key)) != CRYPT_OK) {
56         return err;
57      }
58      f8->padlen = 0;
59   }
60
61#ifdef LTC_FAST
62   if (f8->padlen == 0) {
63      while (len >= (unsigned long)f8->blocklen) {
64         STORE32H(f8->blockcnt, (buf+(f8->blocklen-4)));
65         ++(f8->blockcnt);
66         for (x = 0; x < f8->blocklen; x += sizeof(LTC_FAST_TYPE)) {
67             *((LTC_FAST_TYPE*)(&ct[x])) = *((LTC_FAST_TYPE*)(&pt[x])) ^ *((LTC_FAST_TYPE*)(&f8->IV[x]));
68             *((LTC_FAST_TYPE*)(&f8->IV[x])) ^= *((LTC_FAST_TYPE*)(&f8->MIV[x])) ^ *((LTC_FAST_TYPE*)(&buf[x]));
69         }
70         if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(f8->IV, f8->IV, &f8->key)) != CRYPT_OK) {
71            return err;
72         }
73         len -= x;
74         pt  += x;
75         ct  += x;
76      }
77   }
78#endif
79
80   while (len > 0) {
81       if (f8->padlen == f8->blocklen) {
82          /* xor of IV, MIV and blockcnt == what goes into cipher */
83          STORE32H(f8->blockcnt, (buf+(f8->blocklen-4)));
84          ++(f8->blockcnt);
85          for (x = 0; x < f8->blocklen; x++) {
86              f8->IV[x] ^= f8->MIV[x] ^ buf[x];
87          }
88          if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(f8->IV, f8->IV, &f8->key)) != CRYPT_OK) {
89             return err;
90          }
91          f8->padlen = 0;
92       }
93       *ct++ = *pt++ ^ f8->IV[f8->padlen++];
94       --len;
95   }
96   return CRYPT_OK;
97}
98
99#endif
100
101/* $Source: /cvs/libtom/libtomcrypt/src/modes/f8/f8_encrypt.c,v $ */
102/* $Revision: 1.6 $ */
103/* $Date: 2006/11/05 04:16:32 $ */
104