src/crypto/axtls_aes.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@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 );