97 lines
2.5 KiB
C
97 lines
2.5 KiB
C
/*
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*****************************************************************************
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*
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* File: fko_hmac.c
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*
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* Author: Michael Rash
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*
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* Purpose: Provide HMAC support to SPA communications
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*
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* Copyright 2012 Michael Rash (mbr@cipherdyne.org)
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*
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* License (GNU Public License):
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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* USA
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*
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*****************************************************************************
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*/
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#include "hmac.h"
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typedef struct {
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SHA256_CTX ctx_inside;
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SHA256_CTX ctx_outside;
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unsigned char block_inner_pad[SHA256_BLOCK_LEN];
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unsigned char block_outer_pad[SHA256_BLOCK_LEN];
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} hmac_sha256_ctx;
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static void
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hmac_sha256_init(hmac_sha256_ctx *ctx, const char *key)
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{
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int i = 0;
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for (i=0; i < (int) SHA256_BLOCK_LEN; i++) {
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ctx->block_inner_pad[i] = key[i] ^ 0x36;
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ctx->block_outer_pad[i] = key[i] ^ 0x5c;
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}
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SHA256_Init(&ctx->ctx_inside);
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SHA256_Update(&ctx->ctx_inside, ctx->block_inner_pad, SHA256_BLOCK_LEN);
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SHA256_Init(&ctx->ctx_outside);
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SHA256_Update(&ctx->ctx_outside, ctx->block_outer_pad, SHA256_BLOCK_LEN);
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return;
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}
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static void
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hmac_sha256_update(hmac_sha256_ctx *ctx, const char *msg,
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unsigned int msg_len)
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{
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SHA256_Update(&ctx->ctx_inside, (unsigned char *)msg, msg_len);
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return;
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}
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static void
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hmac_sha256_final(hmac_sha256_ctx *ctx, unsigned char *hmac)
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{
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unsigned char digest_inside[SHA256_DIGEST_LEN];
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SHA256_Final(digest_inside, &ctx->ctx_inside);
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SHA256_Update(&ctx->ctx_outside, digest_inside, SHA256_DIGEST_LEN);
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SHA256_Final(hmac, &ctx->ctx_outside);
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return;
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}
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void
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hmac_sha256(const char *msg, const unsigned int msg_len,
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unsigned char *hmac, const char *hmac_key)
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{
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hmac_sha256_ctx ctx;
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memset(&ctx, 0, sizeof(&ctx));
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hmac_sha256_init(&ctx, hmac_key);
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hmac_sha256_update(&ctx, msg, msg_len);
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hmac_sha256_final(&ctx, hmac);
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return;
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}
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