1 /* 2 * Copyright (c) 2009 Joshua Oreman <oremanj (at) rwcr.net>. 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 <gpxe/crypto.h> 24 #include <gpxe/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 } 124
