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1.1 root 1: /*
2: * Copyright (C) 2007 Michael Brown <[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 <string.h>
22: #include <errno.h>
23: #include <byteswap.h>
24: #include <ipxe/crypto.h>
25: #include <ipxe/cbc.h>
26: #include <ipxe/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 );
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