79 lines
2.0 KiB
C
79 lines
2.0 KiB
C
/*
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* cifra - embedded cryptography library
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* Written in 2014 by Joseph Birr-Pixton <jpixton@gmail.com>
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*
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* To the extent possible under law, the author(s) have dedicated all
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* copyright and related and neighboring rights to this software to the
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* public domain worldwide. This software is distributed without any
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* warranty.
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*
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* You should have received a copy of the CC0 Public Domain Dedication
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* along with this software. If not, see
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* <http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#ifndef HMAC_H
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#define HMAC_H
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#include <stddef.h>
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#include <stdint.h>
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#include "chash.h"
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/**
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* HMAC
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* ====
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* This is a one-shot and incremental interface to computing
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* HMAC with any hash function.
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*
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* (Note: HMAC with SHA3 is possible, but is probably not a
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* sensible thing to want.)
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*/
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/* .. c:type:: cf_hmac_ctx
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* HMAC incremental interface context.
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*
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* .. c:member:: cf_hmac_ctx.hash
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* Hash function description.
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*
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* .. c:member:: cf_hmac_ctx.inner
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* Inner hash computation.
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*
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* .. c:member:: cf_hmac_ctx.outer
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* Outer hash computation.
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*/
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typedef struct
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{
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const cf_chash *hash;
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cf_chash_ctx inner;
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cf_chash_ctx outer;
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} cf_hmac_ctx;
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/* .. c:function:: $DECL
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* Set up ctx for computing a HMAC using the given hash and key. */
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void cf_hmac_init(cf_hmac_ctx *ctx,
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const cf_chash *hash,
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const uint8_t *key, size_t nkey);
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/* .. c:function:: $DECL
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* Input data. */
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void cf_hmac_update(cf_hmac_ctx *ctx,
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const void *data, size_t ndata);
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/* .. c:function:: $DECL
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* Finish and compute HMAC.
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* `ctx->hash->hashsz` bytes are written to `out`. */
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void cf_hmac_finish(cf_hmac_ctx *ctx, uint8_t *out);
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/* .. c:function:: $DECL
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* One shot interface: compute `HMAC_hash(key, msg)`, writing the
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* answer (which is `hash->hashsz` long) to `out`.
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*
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* This function does not fail. */
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void cf_hmac(const uint8_t *key, size_t nkey,
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const uint8_t *msg, size_t nmsg,
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uint8_t *out,
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const cf_chash *hash);
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#endif
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