| // SPDX-License-Identifier: BSD-2-Clause |
| /* 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. |
| */ |
| |
| #include "tomcrypt_private.h" |
| |
| #ifdef LTC_CHACHA20POLY1305_MODE |
| |
| /** |
| Set IV + counter data to the ChaCha20Poly1305 state and reset the context |
| @param st The ChaCha20Poly1305 state |
| @param iv The IV data to add |
| @param ivlen The length of the IV (must be 12 or 8) |
| @return CRYPT_OK on success |
| */ |
| int chacha20poly1305_setiv(chacha20poly1305_state *st, const unsigned char *iv, unsigned long ivlen) |
| { |
| chacha_state tmp_st; |
| int i, err; |
| unsigned char polykey[32]; |
| |
| LTC_ARGCHK(st != NULL); |
| LTC_ARGCHK(iv != NULL); |
| LTC_ARGCHK(ivlen == 12 || ivlen == 8); |
| |
| /* set IV for chacha20 */ |
| if (ivlen == 12) { |
| /* IV 96bit */ |
| if ((err = chacha_ivctr32(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err; |
| } |
| else { |
| /* IV 64bit */ |
| if ((err = chacha_ivctr64(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err; |
| } |
| |
| /* copy chacha20 key to temporary state */ |
| for(i = 0; i < 12; i++) tmp_st.input[i] = st->chacha.input[i]; |
| tmp_st.rounds = 20; |
| /* set IV */ |
| if (ivlen == 12) { |
| /* IV 32bit */ |
| if ((err = chacha_ivctr32(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err; |
| } |
| else { |
| /* IV 64bit */ |
| if ((err = chacha_ivctr64(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err; |
| } |
| /* (re)generate new poly1305 key */ |
| if ((err = chacha_keystream(&tmp_st, polykey, 32)) != CRYPT_OK) return err; |
| /* (re)initialise poly1305 */ |
| if ((err = poly1305_init(&st->poly, polykey, 32)) != CRYPT_OK) return err; |
| st->ctlen = 0; |
| st->aadlen = 0; |
| st->aadflg = 1; |
| |
| return CRYPT_OK; |
| } |
| |
| #endif |
| |
| /* ref: $Format:%D$ */ |
| /* git commit: $Format:%H$ */ |
| /* commit time: $Format:%ai$ */ |