2 cipher.c -- Symmetric block cipher handling
3 Copyright (C) 2007-2022 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>
27 #include "../cipher.h"
28 #include "../logger.h"
30 static void cipher_open(cipher_t *cipher, const EVP_CIPHER *evp_cipher) {
31 cipher->cipher = evp_cipher;
32 cipher->ctx = EVP_CIPHER_CTX_new();
39 bool cipher_open_by_name(cipher_t *cipher, const char *name) {
40 const EVP_CIPHER *evp_cipher = EVP_get_cipherbyname(name);
43 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher name '%s'!", name);
47 cipher_open(cipher, evp_cipher);
51 bool cipher_open_by_nid(cipher_t *cipher, int nid) {
52 const EVP_CIPHER *evp_cipher = EVP_get_cipherbynid(nid);
55 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher nid %d!", nid);
59 cipher_open(cipher, evp_cipher);
63 void cipher_close(cipher_t *cipher) {
69 EVP_CIPHER_CTX_free(cipher->ctx);
72 memset(cipher, 0, sizeof(*cipher));
75 size_t cipher_keylength(const cipher_t *cipher) {
76 if(!cipher || !cipher->cipher) {
80 return EVP_CIPHER_key_length(cipher->cipher) + EVP_CIPHER_iv_length(cipher->cipher);
83 uint64_t cipher_budget(const cipher_t *cipher) {
84 /* Hopefully some failsafe way to calculate the maximum amount of bytes to
85 send/receive with a given cipher before we might run into birthday paradox
86 attacks. Because we might use different modes, the block size of the mode
87 might be 1 byte. In that case, use the IV length. Ensure the whole thing
88 is limited to what can be represented with a 64 bits integer.
91 if(!cipher || !cipher->cipher) {
92 return UINT64_MAX; // NULL cipher
95 int ivlen = EVP_CIPHER_iv_length(cipher->cipher);
96 int blklen = EVP_CIPHER_block_size(cipher->cipher);
97 int len = blklen > 1 ? blklen : ivlen > 1 ? ivlen : 8;
98 int bits = len * 4 - 1;
99 return bits < 64 ? UINT64_C(1) << bits : UINT64_MAX;
102 size_t cipher_blocksize(const cipher_t *cipher) {
103 if(!cipher || !cipher->cipher) {
107 return EVP_CIPHER_block_size(cipher->cipher);
110 bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
114 result = EVP_EncryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + EVP_CIPHER_key_length(cipher->cipher));
116 result = EVP_DecryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + EVP_CIPHER_key_length(cipher->cipher));
123 logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
127 bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
131 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));
133 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));
140 logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
144 bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
148 if(EVP_EncryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
149 && EVP_EncryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, (int)inlen)
150 && EVP_EncryptFinal_ex(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
160 if(EVP_EncryptUpdate(cipher->ctx, outdata, &len, indata, (int)inlen)) {
169 logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
173 bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
177 if(EVP_DecryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
178 && EVP_DecryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, (int)inlen)
179 && EVP_DecryptFinal_ex(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
189 if(EVP_DecryptUpdate(cipher->ctx, outdata, &len, indata, (int)inlen)) {
198 logger(DEBUG_ALWAYS, LOG_ERR, "Error while decrypting: %s", ERR_error_string(ERR_get_error(), NULL));
202 int cipher_get_nid(const cipher_t *cipher) {
203 if(!cipher || !cipher->cipher) {
207 return EVP_CIPHER_nid(cipher->cipher);
210 bool cipher_active(const cipher_t *cipher) {
211 return cipher && cipher->cipher && EVP_CIPHER_nid(cipher->cipher) != 0;