1 /* 2 * Copyright (C) 2007 Michael Brown <mbrown (at) fensystems.co.uk>. 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 <string.h> 22 #include <errno.h> 23 #include <byteswap.h> 24 #include <gpxe/crypto.h> 25 #include <gpxe/cbc.h> 26 #include <gpxe/aes.h> 27 #include "crypto/axtls/crypto.h" 28 29 /** @file 30 * 31 * AES algorithm 32 * 33 */ 34 35 /** 36 * Set key 37 * 38 * @v ctx Context 39 * @v key Key 40 * @v keylen Key length 41 * @ret rc Return status code 42 */ 43 static int aes_setkey ( void *ctx, const void *key, size_t keylen ) { 44 struct aes_context *aes_ctx = ctx; 45 AES_MODE mode; 46 void *iv; 47 48 switch ( keylen ) { 49 case ( 128 / 8 ): 50 mode = AES_MODE_128; 51 break; 52 case ( 256 / 8 ): 53 mode = AES_MODE_256; 54 break; 55 default: 56 return -EINVAL; 57 } 58 59 /* IV is not a relevant concept at this stage; use a dummy 60 * value that will have no side-effects. 61 */ 62 iv = &aes_ctx->axtls_ctx.iv; 63 64 AES_set_key ( &aes_ctx->axtls_ctx, key, iv, mode ); 65 66 aes_ctx->decrypting = 0; 67 68 return 0; 69 } 70 71 /** 72 * Set initialisation vector 73 * 74 * @v ctx Context 75 * @v iv Initialisation vector 76 */ 77 static void aes_setiv ( void *ctx __unused, const void *iv __unused ) { 78 /* Nothing to do */ 79 } 80 81 /** 82 * Call AXTLS' AES_encrypt() or AES_decrypt() functions 83 * 84 * @v axtls_ctx AXTLS AES context 85 * @v src Data to process 86 * @v dst Buffer for output 87 * @v func AXTLS AES function to call 88 */ 89 static void aes_call_axtls ( AES_CTX *axtls_ctx, const void *src, void *dst, 90 void ( * func ) ( const AES_CTX *axtls_ctx, 91 uint32_t *data ) ){ 92 const uint32_t *srcl = src; 93 uint32_t *dstl = dst; 94 unsigned int i; 95 96 /* AXTLS' AES_encrypt() and AES_decrypt() functions both 97 * expect to deal with an array of four dwords in host-endian 98 * order. 99 */ 100 for ( i = 0 ; i < 4 ; i++ ) 101 dstl[i] = ntohl ( srcl[i] ); 102 func ( axtls_ctx, dstl ); 103 for ( i = 0 ; i < 4 ; i++ ) 104 dstl[i] = htonl ( dstl[i] ); 105 } 106 107 /** 108 * Encrypt data 109 * 110 * @v ctx Context 111 * @v src Data to encrypt 112 * @v dst Buffer for encrypted data 113 * @v len Length of data 114 */ 115 static void aes_encrypt ( void *ctx, const void *src, void *dst, 116 size_t len ) { 117 struct aes_context *aes_ctx = ctx; 118 119 assert ( len == AES_BLOCKSIZE ); 120 if ( aes_ctx->decrypting ) 121 assert ( 0 ); 122 aes_call_axtls ( &aes_ctx->axtls_ctx, src, dst, AES_encrypt ); 123 } 124 125 /** 126 * Decrypt data 127 * 128 * @v ctx Context 129 * @v src Data to decrypt 130 * @v dst Buffer for decrypted data 131 * @v len Length of data 132 */ 133 static void aes_decrypt ( void *ctx, const void *src, void *dst, 134 size_t len ) { 135 struct aes_context *aes_ctx = ctx; 136 137 assert ( len == AES_BLOCKSIZE ); 138 if ( ! aes_ctx->decrypting ) { 139 AES_convert_key ( &aes_ctx->axtls_ctx ); 140 aes_ctx->decrypting = 1; 141 } 142 aes_call_axtls ( &aes_ctx->axtls_ctx, src, dst, AES_decrypt ); 143 } 144 145 /** Basic AES algorithm */ 146 struct cipher_algorithm aes_algorithm = { 147 .name = "aes", 148 .ctxsize = sizeof ( struct aes_context ), 149 .blocksize = AES_BLOCKSIZE, 150 .setkey = aes_setkey, 151 .setiv = aes_setiv, 152 .encrypt = aes_encrypt, 153 .decrypt = aes_decrypt, 154 }; 155 156 /* AES with cipher-block chaining */ 157 CBC_CIPHER ( aes_cbc, aes_cbc_algorithm, 158 aes_algorithm, struct aes_context, AES_BLOCKSIZE ); 159