2 * Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 RCSID("$OpenBSD: cipher-ctr.c,v 1.6 2005/07/17 07:17:55 djm Exp $");
19 #include <openssl/evp.h>
24 /* compatibility with old or broken OpenSSL versions */
25 #include "openbsd-compat/openssl-compat.h"
27 #ifdef USE_BUILTIN_RIJNDAEL
29 #define AES_KEY rijndael_ctx
30 #define AES_BLOCK_SIZE 16
31 #define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b)
32 #define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (char *)a, b, 1)
34 #include <openssl/aes.h>
37 const EVP_CIPHER *evp_aes_128_ctr(void);
38 void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
40 struct ssh_aes_ctr_ctx
43 u_char aes_counter[AES_BLOCK_SIZE];
47 * increment counter 'ctr',
48 * the counter is of size 'len' bytes and stored in network-byte-order.
49 * (LSB at ctr[len-1], MSB at ctr[0])
52 ssh_ctr_inc(u_char *ctr, u_int len)
56 for (i = len - 1; i >= 0; i--)
57 if (++ctr[i]) /* continue on overflow */
62 ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
65 struct ssh_aes_ctr_ctx *c;
67 u_char buf[AES_BLOCK_SIZE];
71 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
76 AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
77 ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
79 *(dest++) = *(src++) ^ buf[n];
80 n = (n + 1) % AES_BLOCK_SIZE;
86 ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
89 struct ssh_aes_ctr_ctx *c;
91 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
92 c = xmalloc(sizeof(*c));
93 EVP_CIPHER_CTX_set_app_data(ctx, c);
96 AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8,
99 memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
104 ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
106 struct ssh_aes_ctr_ctx *c;
108 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
109 memset(c, 0, sizeof(*c));
111 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
117 ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
119 struct ssh_aes_ctr_ctx *c;
121 if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
122 fatal("ssh_aes_ctr_iv: no context");
124 memcpy(c->aes_counter, iv, len);
126 memcpy(iv, c->aes_counter, len);
130 evp_aes_128_ctr(void)
132 static EVP_CIPHER aes_ctr;
134 memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
135 aes_ctr.nid = NID_undef;
136 aes_ctr.block_size = AES_BLOCK_SIZE;
137 aes_ctr.iv_len = AES_BLOCK_SIZE;
138 aes_ctr.key_len = 16;
139 aes_ctr.init = ssh_aes_ctr_init;
140 aes_ctr.cleanup = ssh_aes_ctr_cleanup;
141 aes_ctr.do_cipher = ssh_aes_ctr;
143 aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
144 EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;