38 lines
984 B
C
38 lines
984 B
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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/* The implementation is based on:
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* chacha-ref.c version 20080118
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* Public domain from D. J. Bernstein
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*/
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#include "tomcrypt_private.h"
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#ifdef LTC_CHACHA
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/**
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Set IV + counter data to the ChaCha state
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@param st The ChaCha20 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 8)
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@param counter 64bit (unsigned) initial counter value
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@return CRYPT_OK on success
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*/
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int chacha_ivctr64(chacha_state *st, const unsigned char *iv, unsigned long ivlen, ulong64 counter)
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{
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LTC_ARGCHK(st != NULL);
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LTC_ARGCHK(iv != NULL);
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/* 64bit IV + 64bit counter */
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LTC_ARGCHK(ivlen == 8);
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st->input[12] = (ulong32)(counter & 0xFFFFFFFF);
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st->input[13] = (ulong32)(counter >> 32);
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LOAD32L(st->input[14], iv + 0);
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LOAD32L(st->input[15], iv + 4);
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st->ksleft = 0;
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st->ivlen = ivlen;
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return CRYPT_OK;
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}
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#endif
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