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

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2009 Joshua Oreman <[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: #include <stdlib.h>
        !            22: #include <string.h>
        !            23: #include <ipxe/crypto.h>
        !            24: #include <ipxe/aes.h>
        !            25: 
        !            26: /**
        !            27:  * Wrap a key or other data using AES Key Wrap (RFC 3394)
        !            28:  *
        !            29:  * @v kek      Key Encryption Key, 16 bytes
        !            30:  * @v src      Data to encrypt
        !            31:  * @v nblk     Number of 8-byte blocks in @a data
        !            32:  * @ret dest   Encrypted data (8 bytes longer than input)
        !            33:  *
        !            34:  * The algorithm is implemented such that @a src and @a dest may point
        !            35:  * to the same buffer.
        !            36:  */
        !            37: int aes_wrap ( const void *kek, const void *src, void *dest, int nblk )
        !            38: {
        !            39:        u8 *A = dest;
        !            40:        u8 B[16];
        !            41:        u8 *R;
        !            42:        int i, j;
        !            43:        void *aes_ctx = malloc ( AES_CTX_SIZE );
        !            44: 
        !            45:        if ( ! aes_ctx )
        !            46:                return -1;
        !            47: 
        !            48:        cipher_setkey ( &aes_algorithm, aes_ctx, kek, 16 );
        !            49: 
        !            50:        /* Set up */
        !            51:        memset ( A, 0xA6, sizeof ( A ) );
        !            52:        memmove ( dest + 8, src, nblk * 8 );
        !            53: 
        !            54:        /* Wrap */
        !            55:        for ( j = 0; j < 6; j++ ) {
        !            56:                R = dest + 8;
        !            57:                for ( i = 1; i <= nblk; i++ ) {
        !            58:                        memcpy ( B, A, 8 );
        !            59:                        memcpy ( B + 8, R, 8 );
        !            60:                        cipher_encrypt ( &aes_algorithm, aes_ctx, B, B, 16 );
        !            61:                        memcpy ( A, B, 8 );
        !            62:                        A[7] ^= ( nblk * j ) + i;
        !            63:                        memcpy ( R, B + 8, 8 );
        !            64:                        R += 8;
        !            65:                }
        !            66:        }
        !            67: 
        !            68:        free ( aes_ctx );
        !            69:        return 0;
        !            70: }
        !            71: 
        !            72: /**
        !            73:  * Unwrap a key or other data using AES Key Wrap (RFC 3394)
        !            74:  *
        !            75:  * @v kek      Key Encryption Key, 16 bytes
        !            76:  * @v src      Data to decrypt
        !            77:  * @v nblk     Number of 8-byte blocks in @e plaintext key
        !            78:  * @ret dest   Decrypted data (8 bytes shorter than input)
        !            79:  * @ret rc     Zero on success, nonzero on IV mismatch
        !            80:  *
        !            81:  * The algorithm is implemented such that @a src and @a dest may point
        !            82:  * to the same buffer.
        !            83:  */
        !            84: int aes_unwrap ( const void *kek, const void *src, void *dest, int nblk )
        !            85: {
        !            86:        u8 A[8], B[16];
        !            87:        u8 *R;
        !            88:        int i, j;
        !            89:        void *aes_ctx = malloc ( AES_CTX_SIZE );
        !            90: 
        !            91:        if ( ! aes_ctx )
        !            92:                return -1;
        !            93: 
        !            94:        cipher_setkey ( &aes_algorithm, aes_ctx, kek, 16 );
        !            95: 
        !            96:        /* Set up */
        !            97:        memcpy ( A, src, 8 );
        !            98:        memmove ( dest, src + 8, nblk * 8 );
        !            99: 
        !           100:        /* Unwrap */
        !           101:        for ( j = 5; j >= 0; j-- ) {
        !           102:                R = dest + ( nblk - 1 ) * 8;
        !           103:                for ( i = nblk; i >= 1; i-- ) {
        !           104:                        memcpy ( B, A, 8 );
        !           105:                        memcpy ( B + 8, R, 8 );
        !           106:                        B[7] ^= ( nblk * j ) + i;
        !           107:                        cipher_decrypt ( &aes_algorithm, aes_ctx, B, B, 16 );
        !           108:                        memcpy ( A, B, 8 );
        !           109:                        memcpy ( R, B + 8, 8 );
        !           110:                        R -= 8;
        !           111:                }
        !           112:        }
        !           113: 
        !           114:        free ( aes_ctx );
        !           115: 
        !           116:        /* Check IV */
        !           117:        for ( i = 0; i < 8; i++ ) {
        !           118:                if ( A[i] != 0xA6 )
        !           119:                        return -1;
        !           120:        }
        !           121: 
        !           122:        return 0;
        !           123: }

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