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comparison libtomcrypt/src/encauth/chachapoly/chacha20poly1305_setiv.c @ 1471:6dba84798cd5

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Update to libtomcrypt 1.18.1, merged with Dropbear changes
author Matt Johnston <matt@ucc.asn.au>
date Fri, 09 Feb 2018 21:44:05 +0800
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1470:8bba51a55704 1471:6dba84798cd5
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
10 #include "tomcrypt.h"
11
12 #ifdef LTC_CHACHA20POLY1305_MODE
13
14 /**
15 Set IV + counter data to the ChaCha20Poly1305 state and reset the context
16 @param st The ChaCha20Poly1305 state
17 @param iv The IV data to add
18 @param ivlen The length of the IV (must be 12 or 8)
19 @return CRYPT_OK on success
20 */
21 int chacha20poly1305_setiv(chacha20poly1305_state *st, const unsigned char *iv, unsigned long ivlen)
22 {
23 chacha_state tmp_st;
24 int i, err;
25 unsigned char polykey[32];
26
27 LTC_ARGCHK(st != NULL);
28 LTC_ARGCHK(iv != NULL);
29 LTC_ARGCHK(ivlen == 12 || ivlen == 8);
30
31 /* set IV for chacha20 */
32 if (ivlen == 12) {
33 /* IV 96bit */
34 if ((err = chacha_ivctr32(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err;
35 }
36 else {
37 /* IV 64bit */
38 if ((err = chacha_ivctr64(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err;
39 }
40
41 /* copy chacha20 key to temporary state */
42 for(i = 0; i < 12; i++) tmp_st.input[i] = st->chacha.input[i];
43 tmp_st.rounds = 20;
44 /* set IV */
45 if (ivlen == 12) {
46 /* IV 32bit */
47 if ((err = chacha_ivctr32(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err;
48 }
49 else {
50 /* IV 64bit */
51 if ((err = chacha_ivctr64(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err;
52 }
53 /* (re)generate new poly1305 key */
54 if ((err = chacha_keystream(&tmp_st, polykey, 32)) != CRYPT_OK) return err;
55 /* (re)initialise poly1305 */
56 if ((err = poly1305_init(&st->poly, polykey, 32)) != CRYPT_OK) return err;
57 st->ctlen = 0;
58 st->aadlen = 0;
59 st->aadflg = 1;
60
61 return CRYPT_OK;
62 }
63
64 #endif
65
66 /* ref: $Format:%D$ */
67 /* git commit: $Format:%H$ */
68 /* commit time: $Format:%ai$ */