2 cipher.c -- Symmetric block cipher handling
3 Copyright (C) 2007-2016 Guus Sliepen <guus@tinc-vpn.org>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License along
16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 #include "../system.h"
22 #include <openssl/rand.h>
23 #include <openssl/err.h>
24 #include <openssl/evp.h>
26 #include "../cipher.h"
27 #include "../logger.h"
28 #include "../xalloc.h"
32 const EVP_CIPHER *cipher;
35 static cipher_t *cipher_open(const EVP_CIPHER *evp_cipher) {
36 cipher_t *cipher = xzalloc(sizeof *cipher);
37 cipher->cipher = evp_cipher;
38 cipher->ctx = EVP_CIPHER_CTX_new();
45 cipher_t *cipher_open_by_name(const char *name) {
46 const EVP_CIPHER *evp_cipher = EVP_get_cipherbyname(name);
48 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher name '%s'!", name);
52 return cipher_open(evp_cipher);
55 cipher_t *cipher_open_by_nid(int nid) {
56 const EVP_CIPHER *evp_cipher = EVP_get_cipherbynid(nid);
58 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher nid %d!", nid);
62 return cipher_open(evp_cipher);
65 void cipher_close(cipher_t *cipher) {
69 EVP_CIPHER_CTX_free(cipher->ctx);
73 size_t cipher_keylength(const cipher_t *cipher) {
74 if(!cipher || !cipher->cipher)
77 return EVP_CIPHER_key_length(cipher->cipher) + EVP_CIPHER_iv_length(cipher->cipher);
80 uint64_t cipher_budget(const cipher_t *cipher) {
81 /* Hopefully some failsafe way to calculate the maximum amount of bytes to
82 send/receive with a given cipher before we might run into birthday paradox
83 attacks. Because we might use different modes, the block size of the mode
84 might be 1 byte. In that case, use the IV length. Ensure the whole thing
85 is limited to what can be represented with a 64 bits integer.
88 if(!cipher || !cipher->cipher)
89 return UINT64_MAX; // NULL cipher
91 int ivlen = EVP_CIPHER_iv_length(cipher->cipher);
92 int blklen = EVP_CIPHER_block_size(cipher->cipher);
93 int len = blklen > 1 ? blklen : ivlen > 1 ? ivlen : 8;
94 int bits = len * 4 - 1;
95 return bits < 64 ? UINT64_C(1) << bits : UINT64_MAX;
98 size_t cipher_blocksize(const cipher_t *cipher) {
99 if(!cipher || !cipher->cipher)
102 return EVP_CIPHER_block_size(cipher->cipher);
105 bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
109 result = EVP_EncryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + EVP_CIPHER_key_length(cipher->cipher));
111 result = EVP_DecryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + EVP_CIPHER_key_length(cipher->cipher));
116 logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
120 bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
124 result = EVP_EncryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - EVP_CIPHER_key_length(cipher->cipher), (unsigned char *)key + len - EVP_CIPHER_iv_length(cipher->cipher) - EVP_CIPHER_key_length(cipher->cipher));
126 result = EVP_DecryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - EVP_CIPHER_key_length(cipher->cipher), (unsigned char *)key + len - EVP_CIPHER_iv_length(cipher->cipher) - EVP_CIPHER_key_length(cipher->cipher));
131 logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
135 bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
138 if(EVP_EncryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
139 && EVP_EncryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
140 && EVP_EncryptFinal(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
141 if(outlen) *outlen = len + pad;
146 if(EVP_EncryptUpdate(cipher->ctx, outdata, &len, indata, inlen)) {
147 if(outlen) *outlen = len;
152 logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
156 bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
159 if(EVP_DecryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
160 && EVP_DecryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
161 && EVP_DecryptFinal(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
162 if(outlen) *outlen = len + pad;
167 if(EVP_EncryptUpdate(cipher->ctx, outdata, &len, indata, inlen)) {
168 if(outlen) *outlen = len;
173 logger(DEBUG_ALWAYS, LOG_ERR, "Error while decrypting: %s", ERR_error_string(ERR_get_error(), NULL));
177 int cipher_get_nid(const cipher_t *cipher) {
178 if(!cipher || !cipher->cipher)
181 return EVP_CIPHER_nid(cipher->cipher);
184 bool cipher_active(const cipher_t *cipher) {
185 return cipher && cipher->cipher && EVP_CIPHER_nid(cipher->cipher) != 0;