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69 lines
2.0 KiB
C
69 lines
2.0 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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#include "tomcrypt.h"
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#ifdef LTC_CHACHA20POLY1305_MODE
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/**
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Set IV + counter data to the ChaCha20Poly1305 state and reset the context
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@param st The ChaCha20Poly1305 state
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@param iv The IV data to add
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@param ivlen The length of the IV (must be 12 or 8)
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@return CRYPT_OK on success
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*/
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int chacha20poly1305_setiv(chacha20poly1305_state *st, const unsigned char *iv, unsigned long ivlen)
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{
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chacha_state tmp_st;
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int i, err;
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unsigned char polykey[32];
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LTC_ARGCHK(st != NULL);
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LTC_ARGCHK(iv != NULL);
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LTC_ARGCHK(ivlen == 12 || ivlen == 8);
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/* set IV for chacha20 */
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if (ivlen == 12) {
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/* IV 96bit */
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if ((err = chacha_ivctr32(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err;
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}
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else {
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/* IV 64bit */
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if ((err = chacha_ivctr64(&st->chacha, iv, ivlen, 1)) != CRYPT_OK) return err;
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}
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/* copy chacha20 key to temporary state */
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for(i = 0; i < 12; i++) tmp_st.input[i] = st->chacha.input[i];
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tmp_st.rounds = 20;
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/* set IV */
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if (ivlen == 12) {
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/* IV 32bit */
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if ((err = chacha_ivctr32(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err;
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}
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else {
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/* IV 64bit */
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if ((err = chacha_ivctr64(&tmp_st, iv, ivlen, 0)) != CRYPT_OK) return err;
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}
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/* (re)generate new poly1305 key */
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if ((err = chacha_keystream(&tmp_st, polykey, 32)) != CRYPT_OK) return err;
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/* (re)initialise poly1305 */
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if ((err = poly1305_init(&st->poly, polykey, 32)) != CRYPT_OK) return err;
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st->ctlen = 0;
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st->aadlen = 0;
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st->aadflg = 1;
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return CRYPT_OK;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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