1 /* $OpenBSD: cipher-ctr.c,v 1.9 2006/07/22 20:48:22 stevesk Exp $ */
3 * Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
21 #include <openssl/evp.h>
26 /* compatibility with old or broken OpenSSL versions */
27 #include "openbsd-compat/openssl-compat.h"
29 #ifdef USE_BUILTIN_RIJNDAEL
31 #define AES_KEY rijndael_ctx
32 #define AES_BLOCK_SIZE 16
33 #define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b)
34 #define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (char *)a, b, 1)
36 #include <openssl/aes.h>
39 const EVP_CIPHER *evp_aes_128_ctr(void);
40 void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
42 struct ssh_aes_ctr_ctx
45 u_char aes_counter[AES_BLOCK_SIZE];
49 * increment counter 'ctr',
50 * the counter is of size 'len' bytes and stored in network-byte-order.
51 * (LSB at ctr[len-1], MSB at ctr[0])
54 ssh_ctr_inc(u_char *ctr, u_int len)
58 for (i = len - 1; i >= 0; i--)
59 if (++ctr[i]) /* continue on overflow */
64 ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
67 struct ssh_aes_ctr_ctx *c;
69 u_char buf[AES_BLOCK_SIZE];
73 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
78 AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
79 ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
81 *(dest++) = *(src++) ^ buf[n];
82 n = (n + 1) % AES_BLOCK_SIZE;
88 ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
91 struct ssh_aes_ctr_ctx *c;
93 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
94 c = xmalloc(sizeof(*c));
95 EVP_CIPHER_CTX_set_app_data(ctx, c);
98 AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8,
101 memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
106 ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
108 struct ssh_aes_ctr_ctx *c;
110 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
111 memset(c, 0, sizeof(*c));
113 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
119 ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
121 struct ssh_aes_ctr_ctx *c;
123 if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
124 fatal("ssh_aes_ctr_iv: no context");
126 memcpy(c->aes_counter, iv, len);
128 memcpy(iv, c->aes_counter, len);
132 evp_aes_128_ctr(void)
134 static EVP_CIPHER aes_ctr;
136 memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
137 aes_ctr.nid = NID_undef;
138 aes_ctr.block_size = AES_BLOCK_SIZE;
139 aes_ctr.iv_len = AES_BLOCK_SIZE;
140 aes_ctr.key_len = 16;
141 aes_ctr.init = ssh_aes_ctr_init;
142 aes_ctr.cleanup = ssh_aes_ctr_cleanup;
143 aes_ctr.do_cipher = ssh_aes_ctr;
145 aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
146 EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;