Add a return value to crypter_t.encrypt
[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
16 #include "openssl_crypter.h"
17
18 #include <openssl/evp.h>
19
20 typedef struct private_openssl_crypter_t private_openssl_crypter_t;
21
22 /**
23 * Private data of openssl_crypter_t
24 */
25 struct private_openssl_crypter_t {
26
27 /**
28 * Public part of this class.
29 */
30 openssl_crypter_t public;
31
32 /*
33 * the key
34 */
35 chunk_t key;
36
37 /*
38 * the cipher to use
39 */
40 const EVP_CIPHER *cipher;
41 };
42
43 /**
44 * Look up an OpenSSL algorithm name and validate its key size
45 */
46 static char* lookup_algorithm(u_int16_t ikev2_algo, size_t *key_size)
47 {
48 struct {
49 /* identifier specified in IKEv2 */
50 int ikev2_id;
51 /* name of the algorithm, as used in OpenSSL */
52 char *name;
53 /* default key size in bytes */
54 size_t key_def;
55 /* minimum key size */
56 size_t key_min;
57 /* maximum key size */
58 size_t key_max;
59 } mappings[] = {
60 {ENCR_DES, "des", 8, 8, 8},
61 {ENCR_3DES, "des3", 24, 24, 24},
62 {ENCR_RC5, "rc5", 16, 5, 255},
63 {ENCR_IDEA, "idea", 16, 16, 16},
64 {ENCR_CAST, "cast", 16, 5, 16},
65 {ENCR_BLOWFISH, "blowfish", 16, 5, 56},
66 };
67 int i;
68
69 for (i = 0; i < countof(mappings); i++)
70 {
71 if (ikev2_algo == mappings[i].ikev2_id)
72 {
73 /* set the key size if it is not set */
74 if (*key_size == 0)
75 {
76 *key_size = mappings[i].key_def;
77 }
78 /* validate key size */
79 if (*key_size < mappings[i].key_min ||
80 *key_size > mappings[i].key_max)
81 {
82 return NULL;
83 }
84 return mappings[i].name;
85 }
86 }
87 return NULL;
88 }
89
90 /**
91 * Do the actual en/decryption in an EVP context
92 */
93 static bool crypt(private_openssl_crypter_t *this, chunk_t data, chunk_t iv,
94 chunk_t *dst, int enc)
95 {
96 int len;
97 u_char *out;
98
99 out = data.ptr;
100 if (dst)
101 {
102 *dst = chunk_alloc(data.len);
103 out = dst->ptr;
104 }
105 EVP_CIPHER_CTX ctx;
106 EVP_CIPHER_CTX_init(&ctx);
107 return EVP_CipherInit_ex(&ctx, this->cipher, NULL, NULL, NULL, enc) &&
108 EVP_CIPHER_CTX_set_padding(&ctx, 0) /* disable padding */ &&
109 EVP_CIPHER_CTX_set_key_length(&ctx, this->key.len) &&
110 EVP_CipherInit_ex(&ctx, NULL, NULL, this->key.ptr, iv.ptr, enc) &&
111 EVP_CipherUpdate(&ctx, out, &len, data.ptr, data.len) &&
112 /* since padding is disabled this does nothing */
113 EVP_CipherFinal_ex(&ctx, out + len, &len) &&
114 EVP_CIPHER_CTX_cleanup(&ctx);
115 }
116
117 METHOD(crypter_t, decrypt, void,
118 private_openssl_crypter_t *this, chunk_t data, chunk_t iv, chunk_t *dst)
119 {
120 crypt(this, data, iv, dst, 0);
121 }
122
123 METHOD(crypter_t, encrypt, bool,
124 private_openssl_crypter_t *this, chunk_t data, chunk_t iv, chunk_t *dst)
125 {
126 return crypt(this, data, iv, dst, 1);
127 }
128
129 METHOD(crypter_t, get_block_size, size_t,
130 private_openssl_crypter_t *this)
131 {
132 return this->cipher->block_size;
133 }
134
135 METHOD(crypter_t, get_iv_size, size_t,
136 private_openssl_crypter_t *this)
137 {
138 return this->cipher->block_size;
139 }
140
141 METHOD(crypter_t, get_key_size, size_t,
142 private_openssl_crypter_t *this)
143 {
144 return this->key.len;
145 }
146
147 METHOD(crypter_t, set_key, void,
148 private_openssl_crypter_t *this, chunk_t key)
149 {
150 memcpy(this->key.ptr, key.ptr, min(key.len, this->key.len));
151 }
152
153 METHOD(crypter_t, destroy, void,
154 private_openssl_crypter_t *this)
155 {
156 chunk_clear(&this->key);
157 free(this);
158 }
159
160 /*
161 * Described in header
162 */
163 openssl_crypter_t *openssl_crypter_create(encryption_algorithm_t algo,
164 size_t key_size)
165 {
166 private_openssl_crypter_t *this;
167
168 INIT(this,
169 .public = {
170 .crypter = {
171 .encrypt = _encrypt,
172 .decrypt = _decrypt,
173 .get_block_size = _get_block_size,
174 .get_iv_size = _get_iv_size,
175 .get_key_size = _get_key_size,
176 .set_key = _set_key,
177 .destroy = _destroy,
178 },
179 },
180 );
181
182 switch (algo)
183 {
184 case ENCR_NULL:
185 this->cipher = EVP_enc_null();
186 key_size = 0;
187 break;
188 case ENCR_AES_CBC:
189 switch (key_size)
190 {
191 case 0:
192 key_size = 16;
193 /* FALL */
194 case 16: /* AES 128 */
195 this->cipher = EVP_get_cipherbyname("aes128");
196 break;
197 case 24: /* AES-192 */
198 this->cipher = EVP_get_cipherbyname("aes192");
199 break;
200 case 32: /* AES-256 */
201 this->cipher = EVP_get_cipherbyname("aes256");
202 break;
203 default:
204 free(this);
205 return NULL;
206 }
207 break;
208 case ENCR_CAMELLIA_CBC:
209 switch (key_size)
210 {
211 case 0:
212 key_size = 16;
213 /* FALL */
214 case 16: /* CAMELLIA 128 */
215 this->cipher = EVP_get_cipherbyname("camellia128");
216 break;
217 case 24: /* CAMELLIA 192 */
218 this->cipher = EVP_get_cipherbyname("camellia192");
219 break;
220 case 32: /* CAMELLIA 256 */
221 this->cipher = EVP_get_cipherbyname("camellia256");
222 break;
223 default:
224 free(this);
225 return NULL;
226 }
227 break;
228 case ENCR_DES_ECB:
229 key_size = 8;
230 this->cipher = EVP_des_ecb();
231 break;
232 default:
233 {
234 char* name;
235
236 name = lookup_algorithm(algo, &key_size);
237 if (!name)
238 {
239 /* algo unavailable or key_size invalid */
240 free(this);
241 return NULL;
242 }
243 this->cipher = EVP_get_cipherbyname(name);
244 break;
245 }
246 }
247
248 if (!this->cipher)
249 {
250 /* OpenSSL does not support the requested algo */
251 free(this);
252 return NULL;
253 }
254
255 this->key = chunk_alloc(key_size);
256
257 return &this->public;
258 }