crypter_t api supports in-place encryption using NULL as output parameter
[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 /* validate key size */
103 if (key_size < openssl_algo->key_size_min ||
104 key_size > openssl_algo->key_size_max)
105 {
106 return NULL;
107 }
108 return openssl_algo->name;
109 }
110 openssl_algo++;
111 }
112 return NULL;
113 }
114
115 static void crypt(private_openssl_crypter_t *this, chunk_t data,
116 chunk_t iv, chunk_t *dst, int enc)
117 {
118 int len;
119 u_char *out;
120
121 out = data.ptr;
122 if (dst)
123 {
124 *dst = chunk_alloc(data.len);
125 out = dst->ptr;
126 }
127 EVP_CIPHER_CTX ctx;
128 EVP_CIPHER_CTX_init(&ctx);
129 EVP_CipherInit_ex(&ctx, this->cipher, NULL, this->key.ptr, iv.ptr, enc);
130 EVP_CIPHER_CTX_set_padding(&ctx, 0); /* disable padding */
131 EVP_CipherUpdate(&ctx, out, &len, data.ptr, data.len);
132 EVP_CipherFinal_ex(&ctx, out, &len); /* since padding is disabled this does nothing */
133 EVP_CIPHER_CTX_cleanup(&ctx);
134 }
135
136 /**
137 * Implementation of crypter_t.decrypt.
138 */
139 static void decrypt(private_openssl_crypter_t *this, chunk_t data,
140 chunk_t iv, chunk_t *dst)
141 {
142 crypt(this, data, iv, dst, 0);
143 }
144
145
146 /**
147 * Implementation of crypter_t.encrypt.
148 */
149 static void encrypt (private_openssl_crypter_t *this, chunk_t data,
150 chunk_t iv, chunk_t *dst)
151 {
152 crypt(this, data, iv, dst, 1);
153 }
154
155 /**
156 * Implementation of crypter_t.get_block_size.
157 */
158 static size_t get_block_size(private_openssl_crypter_t *this)
159 {
160 return this->cipher->block_size;
161 }
162
163 /**
164 * Implementation of crypter_t.get_key_size.
165 */
166 static size_t get_key_size(private_openssl_crypter_t *this)
167 {
168 return this->key.len;
169 }
170
171 /**
172 * Implementation of crypter_t.set_key.
173 */
174 static void set_key(private_openssl_crypter_t *this, chunk_t key)
175 {
176 memcpy(this->key.ptr, key.ptr, min(key.len, this->key.len));
177 }
178
179 /**
180 * Implementation of crypter_t.destroy.
181 */
182 static void destroy (private_openssl_crypter_t *this)
183 {
184 free(this->key.ptr);
185 free(this);
186 }
187
188 /*
189 * Described in header
190 */
191 openssl_crypter_t *openssl_crypter_create(encryption_algorithm_t algo,
192 size_t key_size)
193 {
194 private_openssl_crypter_t *this;
195
196 this = malloc_thing(private_openssl_crypter_t);
197
198 switch (algo)
199 {
200 case ENCR_NULL:
201 this->cipher = EVP_enc_null();
202 break;
203 case ENCR_AES_CBC:
204 switch (key_size)
205 {
206 case 16: /* AES 128 */
207 this->cipher = EVP_get_cipherbyname("aes128");
208 break;
209 case 24: /* AES-192 */
210 this->cipher = EVP_get_cipherbyname("aes192");
211 break;
212 case 32: /* AES-256 */
213 this->cipher = EVP_get_cipherbyname("aes256");
214 break;
215 default:
216 free(this);
217 return NULL;
218 }
219 break;
220 default:
221 {
222 char* name = lookup_algorithm(encryption_algs, algo, key_size);
223 if (!name)
224 {
225 /* algo unavailable or key_size invalid */
226 free(this);
227 return NULL;
228 }
229 this->cipher = EVP_get_cipherbyname(name);
230 break;
231 }
232 }
233
234 if (!this->cipher)
235 {
236 /* OpenSSL does not support the requested algo */
237 free(this);
238 return NULL;
239 }
240
241 this->key = chunk_alloc(key_size);
242
243 this->public.crypter_interface.encrypt = (void (*) (crypter_t *, chunk_t,chunk_t, chunk_t *)) encrypt;
244 this->public.crypter_interface.decrypt = (void (*) (crypter_t *, chunk_t , chunk_t, chunk_t *)) decrypt;
245 this->public.crypter_interface.get_block_size = (size_t (*) (crypter_t *)) get_block_size;
246 this->public.crypter_interface.get_key_size = (size_t (*) (crypter_t *)) get_key_size;
247 this->public.crypter_interface.set_key = (void (*) (crypter_t *,chunk_t)) set_key;
248 this->public.crypter_interface.destroy = (void (*) (crypter_t *)) destroy;
249
250 return &this->public;
251 }