43 lines
1.3 KiB
C
43 lines
1.3 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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Terminate a ChaCha20Poly1305 stream
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@param st The ChaCha20Poly1305 state
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@param tag [out] The destination for the MAC tag
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@param taglen [in/out] The length of the MAC tag
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@return CRYPT_OK on success
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*/
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int chacha20poly1305_done(chacha20poly1305_state *st, unsigned char *tag, unsigned long *taglen)
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{
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unsigned char padzero[16] = { 0 };
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unsigned long padlen;
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unsigned char buf[16];
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int err;
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LTC_ARGCHK(st != NULL);
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padlen = 16 - (st->ctlen % 16);
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if (padlen < 16) {
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if ((err = poly1305_process(&st->poly, padzero, padlen)) != CRYPT_OK) return err;
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}
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STORE64L(st->aadlen, buf);
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STORE64L(st->ctlen, buf + 8);
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if ((err = poly1305_process(&st->poly, buf, 16)) != CRYPT_OK) return err;
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if ((err = poly1305_done(&st->poly, tag, taglen)) != CRYPT_OK) return err;
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if ((err = chacha_done(&st->chacha)) != CRYPT_OK) return err;
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return CRYPT_OK;
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}
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#endif
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