Return to hmac.c CVS log

Up to [Qemu by Fabrice Bellard] / qemu / roms / ipxe / src / crypto

Annotation of qemu/roms/ipxe/src/crypto/hmac.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (C) 2007 Michael Brown <[email protected]>.
        !             3:  *
        !             4:  * This program is free software; you can redistribute it and/or
        !             5:  * modify it under the terms of the GNU General Public License as
        !             6:  * published by the Free Software Foundation; either version 2 of the
        !             7:  * License, or any later version.
        !             8:  *
        !             9:  * This program is distributed in the hope that it will be useful, but
        !            10:  * WITHOUT ANY WARRANTY; without even the implied warranty of
        !            11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        !            12:  * General Public License for more details.
        !            13:  *
        !            14:  * You should have received a copy of the GNU General Public License
        !            15:  * along with this program; if not, write to the Free Software
        !            16:  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            17:  */
        !            18: 
        !            19: FILE_LICENCE ( GPL2_OR_LATER );
        !            20: 
        !            21: /**
        !            22:  * @file
        !            23:  *
        !            24:  * Keyed-Hashing for Message Authentication
        !            25:  */
        !            26: 
        !            27: #include <string.h>
        !            28: #include <assert.h>
        !            29: #include <ipxe/crypto.h>
        !            30: #include <ipxe/hmac.h>
        !            31: 
        !            32: /**
        !            33:  * Reduce HMAC key length
        !            34:  *
        !            35:  * @v digest           Digest algorithm to use
        !            36:  * @v digest_ctx       Digest context
        !            37:  * @v key              Key
        !            38:  * @v key_len          Length of key
        !            39:  */
        !            40: static void hmac_reduce_key ( struct digest_algorithm *digest,
        !            41:                              void *key, size_t *key_len ) {
        !            42:        uint8_t digest_ctx[digest->ctxsize];
        !            43: 
        !            44:        digest_init ( digest, digest_ctx );
        !            45:        digest_update ( digest, digest_ctx, key, *key_len );
        !            46:        digest_final ( digest, digest_ctx, key );
        !            47:        *key_len = digest->digestsize;
        !            48: }
        !            49: 
        !            50: /**
        !            51:  * Initialise HMAC
        !            52:  *
        !            53:  * @v digest           Digest algorithm to use
        !            54:  * @v digest_ctx       Digest context
        !            55:  * @v key              Key
        !            56:  * @v key_len          Length of key
        !            57:  *
        !            58:  * The length of the key should be less than the block size of the
        !            59:  * digest algorithm being used.  (If the key length is greater, it
        !            60:  * will be replaced with its own digest, and key_len will be updated
        !            61:  * accordingly).
        !            62:  */
        !            63: void hmac_init ( struct digest_algorithm *digest, void *digest_ctx,
        !            64:                 void *key, size_t *key_len ) {
        !            65:        unsigned char k_ipad[digest->blocksize];
        !            66:        unsigned int i;
        !            67: 
        !            68:        /* Reduce key if necessary */
        !            69:        if ( *key_len > sizeof ( k_ipad ) )
        !            70:                hmac_reduce_key ( digest, key, key_len );
        !            71: 
        !            72:        /* Construct input pad */
        !            73:        memset ( k_ipad, 0, sizeof ( k_ipad ) );
        !            74:        memcpy ( k_ipad, key, *key_len );
        !            75:        for ( i = 0 ; i < sizeof ( k_ipad ) ; i++ ) {
        !            76:                k_ipad[i] ^= 0x36;
        !            77:        }
        !            78:        
        !            79:        /* Start inner hash */
        !            80:        digest_init ( digest, digest_ctx );
        !            81:        digest_update ( digest, digest_ctx, k_ipad, sizeof ( k_ipad ) );
        !            82: }
        !            83: 
        !            84: /**
        !            85:  * Finalise HMAC
        !            86:  *
        !            87:  * @v digest           Digest algorithm to use
        !            88:  * @v digest_ctx       Digest context
        !            89:  * @v key              Key
        !            90:  * @v key_len          Length of key
        !            91:  * @v hmac             HMAC digest to fill in
        !            92:  *
        !            93:  * The length of the key should be less than the block size of the
        !            94:  * digest algorithm being used.  (If the key length is greater, it
        !            95:  * will be replaced with its own digest, and key_len will be updated
        !            96:  * accordingly).
        !            97:  */
        !            98: void hmac_final ( struct digest_algorithm *digest, void *digest_ctx,
        !            99:                  void *key, size_t *key_len, void *hmac ) {
        !           100:        unsigned char k_opad[digest->blocksize];
        !           101:        unsigned int i;
        !           102: 
        !           103:        /* Reduce key if necessary */
        !           104:        if ( *key_len > sizeof ( k_opad ) )
        !           105:                hmac_reduce_key ( digest, key, key_len );
        !           106: 
        !           107:        /* Construct output pad */
        !           108:        memset ( k_opad, 0, sizeof ( k_opad ) );
        !           109:        memcpy ( k_opad, key, *key_len );
        !           110:        for ( i = 0 ; i < sizeof ( k_opad ) ; i++ ) {
        !           111:                k_opad[i] ^= 0x5c;
        !           112:        }
        !           113:        
        !           114:        /* Finish inner hash */
        !           115:        digest_final ( digest, digest_ctx, hmac );
        !           116: 
        !           117:        /* Perform outer hash */
        !           118:        digest_init ( digest, digest_ctx );
        !           119:        digest_update ( digest, digest_ctx, k_opad, sizeof ( k_opad ) );
        !           120:        digest_update ( digest, digest_ctx, hmac, digest->digestsize );
        !           121:        digest_final ( digest, digest_ctx, hmac );
        !           122: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.