From Code to Community: Sponsoring The Perl and Raku Conference 2025 Learn more

MIK / CryptX-0.060_001 / src / ltc / encauth / ocb3 / ocb3_add_aad.c 

            

              
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106

              
/* 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.
 */
/**
   @file ocb3_add_aad.c
   OCB implementation, add AAD data, by Karel Miko
*/
#include "tomcrypt.h"
#ifdef LTC_OCB3_MODE
/**
   Add one block of AAD data (internal function)
   @param ocb        The OCB state
   @param aad_block  [in] AAD data (block_len size)
   @return CRYPT_OK if successful
*/
static int _ocb3_int_aad_add_block(ocb3_state *ocb, const unsigned char *aad_block)
{
   unsigned char tmp[MAXBLOCKSIZE];
   int err;
   /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
   ocb3_int_xor_blocks(ocb->aOffset_current, ocb->aOffset_current, ocb->L_[ocb3_int_ntz(ocb->ablock_index)], ocb->block_len);
   /* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */
   ocb3_int_xor_blocks(tmp, aad_block, ocb->aOffset_current, ocb->block_len);
   if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) {
     return err;
   }
   ocb3_int_xor_blocks(ocb->aSum_current, ocb->aSum_current, tmp, ocb->block_len);
   ocb->ablock_index++;
   return CRYPT_OK;
}
/**
   Add AAD - additional associated data
   @param ocb       The OCB state
   @param aad       The AAD data
   @param aadlen    The size of AAD data (octets)
   @return CRYPT_OK if successful
*/
int ocb3_add_aad(ocb3_state *ocb, const unsigned char *aad, unsigned long aadlen)
{
   int err, x, full_blocks, full_blocks_len, last_block_len;
   unsigned char *data;
   unsigned long datalen, l;
   LTC_ARGCHK(ocb != NULL);
   if (aadlen == 0) return CRYPT_OK;
   LTC_ARGCHK(aad != NULL);
   if (ocb->adata_buffer_bytes > 0) {
     l = ocb->block_len - ocb->adata_buffer_bytes;
     if (l > aadlen) l = aadlen;
     XMEMCPY(ocb->adata_buffer+ocb->adata_buffer_bytes, aad, l);
     ocb->adata_buffer_bytes += l;
     if (ocb->adata_buffer_bytes == ocb->block_len) {
       if ((err = _ocb3_int_aad_add_block(ocb, ocb->adata_buffer)) != CRYPT_OK) {
         return err;
       }
       ocb->adata_buffer_bytes = 0;
     }
     data = (unsigned char *)aad + l;
     datalen = aadlen - l;
   }
   else {
     data = (unsigned char *)aad;
     datalen = aadlen;
   }
   if (datalen == 0) return CRYPT_OK;
   full_blocks = datalen/ocb->block_len;
   full_blocks_len = full_blocks * ocb->block_len;
   last_block_len = datalen - full_blocks_len;
   for (x=0; x<full_blocks; x++) {
     if ((err = _ocb3_int_aad_add_block(ocb, data+x*ocb->block_len)) != CRYPT_OK) {
       return err;
     }
   }
   if (last_block_len>0) {
     XMEMCPY(ocb->adata_buffer, data+full_blocks_len, last_block_len);
     ocb->adata_buffer_bytes = last_block_len;
   }
   return CRYPT_OK;
}
#endif
/* ref:         $Format:%D$ */
/* git commit:  $Format:%H$ */
/* commit time: $Format:%ai$ */