1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */
2 /* SPDX-License-Identifier: Unlicense */
3
4 /* The implementation is based on:
5 * chacha-ref.c version 20080118
6 * Public domain from D. J. Bernstein
7 */
8
9 #include "tomcrypt_private.h"
10
11 #ifdef LTC_CHACHA
12
13 /**
14 Set IV + counter data to the ChaCha state
15 @param st The ChaCha20 state
16 @param iv The IV data to add
17 @param ivlen The length of the IV (must be 12)
18 @param counter 32bit (unsigned) initial counter value
19 @return CRYPT_OK on success
20 */
chacha_ivctr32(chacha_state * st,const unsigned char * iv,unsigned long ivlen,ulong32 counter)21 int chacha_ivctr32(chacha_state *st, const unsigned char *iv, unsigned long ivlen, ulong32 counter)
22 {
23 LTC_ARGCHK(st != NULL);
24 LTC_ARGCHK(iv != NULL);
25 /* 96bit IV + 32bit counter */
26 LTC_ARGCHK(ivlen == 12);
27
28 st->input[12] = counter;
29 LOAD32L(st->input[13], iv + 0);
30 LOAD32L(st->input[14], iv + 4);
31 LOAD32L(st->input[15], iv + 8);
32 st->ksleft = 0;
33 st->ivlen = ivlen;
34 return CRYPT_OK;
35 }
36
37 #endif
38