handle default key sizes in openssl_crypter
[strongswan.git] / src / libstrongswan / plugins / openssl / openssl_crypter.c
1 /*
2 * Copyright (C) 2008 Tobias Brunner
3 * Hochschule fuer Technik Rapperswil
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the
7 * Free Software Foundation; either version 2 of the License, or (at your
8 * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
12 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * for more details.
14 *
15 * $Id$
16 */
17
18 #include "openssl_crypter.h"
19
20 #include <openssl/evp.h>
21
22 typedef struct private_openssl_crypter_t private_openssl_crypter_t;
23
24 /**
25 * Private data of openssl_crypter_t
26 */
27 struct private_openssl_crypter_t {
28
29 /**
30 * Public part of this class.
31 */
32 openssl_crypter_t public;
33
34 /*
35 * the key
36 */
37 chunk_t key;
38
39 /*
40 * the cipher to use
41 */
42 const EVP_CIPHER *cipher;
43 };
44
45 /**
46 * Mapping from the algorithms defined in IKEv2 to
47 * OpenSSL algorithm names and their key length
48 */
49 typedef struct {
50 /**
51 * Identifier specified in IKEv2
52 */
53 int ikev2_id;
54
55 /**
56 * Name of the algorithm, as used in OpenSSL
57 */
58 char *name;
59
60 /**
61 * Minimum valid key length in bytes
62 */
63 size_t key_size_min;
64
65 /**
66 * Maximum valid key length in bytes
67 */
68 size_t key_size_max;
69 } openssl_algorithm_t;
70
71 #define END_OF_LIST -1
72
73 /**
74 * Algorithms for encryption
75 */
76 static openssl_algorithm_t encryption_algs[] = {
77 /* {ENCR_DES_IV64, "***", 0, 0}, */
78 {ENCR_DES, "des", 8, 8}, /* 64 bits */
79 {ENCR_3DES, "des3", 24, 24}, /* 192 bits */
80 {ENCR_RC5, "rc5", 5, 255}, /* 40 to 2040 bits, RFC 2451 */
81 {ENCR_IDEA, "idea", 16, 16}, /* 128 bits, RFC 2451 */
82 {ENCR_CAST, "cast", 5, 16}, /* 40 to 128 bits, RFC 2451 */
83 {ENCR_BLOWFISH, "blowfish", 5, 56}, /* 40 to 448 bits, RFC 2451 */
84 /* {ENCR_3IDEA, "***", 0, 0}, */
85 /* {ENCR_DES_IV32, "***", 0, 0}, */
86 /* {ENCR_NULL, "***", 0, 0}, */ /* handled separately */
87 /* {ENCR_AES_CBC, "***", 0, 0}, */ /* handled separately */
88 /* {ENCR_AES_CTR, "***", 0, 0}, */ /* disabled in evp.h */
89 {END_OF_LIST, NULL, 0, 0},
90 };
91
92 /**
93 * Look up an OpenSSL algorithm name and validate its key size
94 */
95 static char* lookup_algorithm(openssl_algorithm_t *openssl_algo,
96 u_int16_t ikev2_algo, size_t *key_size)
97 {
98 while (openssl_algo->ikev2_id != END_OF_LIST)
99 {
100 if (ikev2_algo == openssl_algo->ikev2_id)
101 {
102 /* set the key size if it is not set */
103 if (*key_size == 0 &&
104 (openssl_algo->key_size_min == openssl_algo->key_size_max))
105 {
106 *key_size = openssl_algo->key_size_min;
107 }
108
109 /* validate key size */
110 if (*key_size < openssl_algo->key_size_min ||
111 *key_size > openssl_algo->key_size_max)
112 {
113 return NULL;
114 }
115 return openssl_algo->name;
116 }
117 openssl_algo++;
118 }
119 return NULL;
120 }
121
122 static void crypt(private_openssl_crypter_t *this, chunk_t data,
123 chunk_t iv, chunk_t *dst, int enc)
124 {
125 int len;
126 u_char *out;
127
128 out = data.ptr;
129 if (dst)
130 {
131 *dst = chunk_alloc(data.len);
132 out = dst->ptr;
133 }
134 EVP_CIPHER_CTX ctx;
135 EVP_CIPHER_CTX_init(&ctx);
136 EVP_CipherInit_ex(&ctx, this->cipher, NULL, this->key.ptr, iv.ptr, enc);
137 EVP_CIPHER_CTX_set_padding(&ctx, 0); /* disable padding */
138 EVP_CipherUpdate(&ctx, out, &len, data.ptr, data.len);
139 EVP_CipherFinal_ex(&ctx, out, &len); /* since padding is disabled this does nothing */
140 EVP_CIPHER_CTX_cleanup(&ctx);
141 }
142
143 /**
144 * Implementation of crypter_t.decrypt.
145 */
146 static void decrypt(private_openssl_crypter_t *this, chunk_t data,
147 chunk_t iv, chunk_t *dst)
148 {
149 crypt(this, data, iv, dst, 0);
150 }
151
152
153 /**
154 * Implementation of crypter_t.encrypt.
155 */
156 static void encrypt (private_openssl_crypter_t *this, chunk_t data,
157 chunk_t iv, chunk_t *dst)
158 {
159 crypt(this, data, iv, dst, 1);
160 }
161
162 /**
163 * Implementation of crypter_t.get_block_size.
164 */
165 static size_t get_block_size(private_openssl_crypter_t *this)
166 {
167 return this->cipher->block_size;
168 }
169
170 /**
171 * Implementation of crypter_t.get_key_size.
172 */
173 static size_t get_key_size(private_openssl_crypter_t *this)
174 {
175 return this->key.len;
176 }
177
178 /**
179 * Implementation of crypter_t.set_key.
180 */
181 static void set_key(private_openssl_crypter_t *this, chunk_t key)
182 {
183 memcpy(this->key.ptr, key.ptr, min(key.len, this->key.len));
184 }
185
186 /**
187 * Implementation of crypter_t.destroy.
188 */
189 static void destroy (private_openssl_crypter_t *this)
190 {
191 free(this->key.ptr);
192 free(this);
193 }
194
195 /*
196 * Described in header
197 */
198 openssl_crypter_t *openssl_crypter_create(encryption_algorithm_t algo,
199 size_t key_size)
200 {
201 private_openssl_crypter_t *this;
202
203 this = malloc_thing(private_openssl_crypter_t);
204
205 switch (algo)
206 {
207 case ENCR_NULL:
208 this->cipher = EVP_enc_null();
209 break;
210 case ENCR_AES_CBC:
211 switch (key_size)
212 {
213 case 16: /* AES 128 */
214 this->cipher = EVP_get_cipherbyname("aes128");
215 break;
216 case 24: /* AES-192 */
217 this->cipher = EVP_get_cipherbyname("aes192");
218 break;
219 case 32: /* AES-256 */
220 this->cipher = EVP_get_cipherbyname("aes256");
221 break;
222 default:
223 free(this);
224 return NULL;
225 }
226 break;
227 default:
228 {
229 char* name = lookup_algorithm(encryption_algs, algo, &key_size);
230 if (!name)
231 {
232 /* algo unavailable or key_size invalid */
233 free(this);
234 return NULL;
235 }
236 this->cipher = EVP_get_cipherbyname(name);
237 break;
238 }
239 }
240
241 if (!this->cipher)
242 {
243 /* OpenSSL does not support the requested algo */
244 free(this);
245 return NULL;
246 }
247
248 this->key = chunk_alloc(key_size);
249
250 this->public.crypter_interface.encrypt = (void (*) (crypter_t *, chunk_t,chunk_t, chunk_t *)) encrypt;
251 this->public.crypter_interface.decrypt = (void (*) (crypter_t *, chunk_t , chunk_t, chunk_t *)) decrypt;
252 this->public.crypter_interface.get_block_size = (size_t (*) (crypter_t *)) get_block_size;
253 this->public.crypter_interface.get_key_size = (size_t (*) (crypter_t *)) get_key_size;
254 this->public.crypter_interface.set_key = (void (*) (crypter_t *,chunk_t)) set_key;
255 this->public.crypter_interface.destroy = (void (*) (crypter_t *)) destroy;
256
257 return &this->public;
258 }