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 */
aes_setkey(void * ctx,const void * key,size_t keylen)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 */
aes_setiv(void * ctx __unused,const void * iv __unused)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 */
aes_call_axtls(AES_CTX * axtls_ctx,const void * src,void * dst,void (* func)(const AES_CTX * axtls_ctx,uint32_t * data))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 */
aes_encrypt(void * ctx,const void * src,void * dst,size_t len)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 */
aes_decrypt(void * ctx,const void * src,void * dst,size_t len)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