mirror of https://github.com/ipxe/ipxe.git
108 lines
3.2 KiB
C
108 lines
3.2 KiB
C
/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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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 as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* 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., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*
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* Alternatively, you may distribute this code in source or binary
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* form, with or without modification, provided that the following
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* conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the above disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the above
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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/**
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* @file
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*
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* Keyed-Hashing for Message Authentication
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*/
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#include <string.h>
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#include <assert.h>
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#include <ipxe/crypto.h>
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#include <ipxe/hmac.h>
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/**
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* Initialise HMAC
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*
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* @v digest Digest algorithm to use
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* @v ctx HMAC context
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* @v key Key
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* @v key_len Length of key
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*/
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void hmac_init ( struct digest_algorithm *digest, void *ctx, const void *key,
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size_t key_len ) {
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hmac_context_t ( digest ) *hctx = ctx;
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unsigned int i;
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/* Construct input pad */
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memset ( hctx->pad, 0, sizeof ( hctx->pad ) );
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if ( key_len <= sizeof ( hctx->pad ) ) {
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memcpy ( hctx->pad, key, key_len );
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} else {
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digest_init ( digest, hctx->ctx );
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digest_update ( digest, hctx->ctx, key, key_len );
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digest_final ( digest, hctx->ctx, hctx->pad );
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}
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for ( i = 0 ; i < sizeof ( hctx->pad ) ; i++ ) {
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hctx->pad[i] ^= 0x36;
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}
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/* Start inner hash */
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digest_init ( digest, hctx->ctx );
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digest_update ( digest, hctx->ctx, hctx->pad, sizeof ( hctx->pad ) );
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}
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/**
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* Finalise HMAC
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*
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* @v digest Digest algorithm to use
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* @v ctx HMAC context
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* @v hmac HMAC digest to fill in
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*/
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void hmac_final ( struct digest_algorithm *digest, void *ctx, void *hmac ) {
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hmac_context_t ( digest ) *hctx = ctx;
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unsigned int i;
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/* Construct output pad from input pad */
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for ( i = 0 ; i < sizeof ( hctx->pad ) ; i++ ) {
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hctx->pad[i] ^= 0x6a;
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}
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/* Finish inner hash */
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digest_final ( digest, hctx->ctx, hmac );
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/* Perform outer hash */
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digest_init ( digest, hctx->ctx );
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digest_update ( digest, hctx->ctx, hctx->pad, sizeof ( hctx->pad ) );
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digest_update ( digest, hctx->ctx, hmac, digest->digestsize );
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digest_final ( digest, hctx->ctx, hmac );
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/* Erase output pad (from which the key may be derivable) */
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memset ( hctx->pad, 0, sizeof ( hctx->pad ) );
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}
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