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 1.2 2003/06/17 18:14:23 markus Exp $");
19 #include <openssl/evp.h>
24 #if OPENSSL_VERSION_NUMBER < 0x00907000L
26 #define AES_KEY rijndael_ctx
27 #define AES_BLOCK_SIZE 16
28 #define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b)
29 #define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (char *)a, b, 1)
31 #include <openssl/aes.h>
34 const EVP_CIPHER *evp_aes_128_ctr(void);
35 void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
37 struct ssh_aes_ctr_ctx
40 u_char aes_counter[AES_BLOCK_SIZE];
44 * increment counter 'ctr',
45 * the counter is of size 'len' bytes and stored in network-byte-order.
46 * (LSB at ctr[len-1], MSB at ctr[0])
49 ssh_ctr_inc(u_char *ctr, u_int len)
53 for (i = len - 1; i >= 0; i--)
54 if (++ctr[i]) /* continue on overflow */
59 ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
62 struct ssh_aes_ctr_ctx *c;
64 u_char buf[AES_BLOCK_SIZE];
68 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
73 AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
74 ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
76 *(dest++) = *(src++) ^ buf[n];
77 n = (n + 1) % AES_BLOCK_SIZE;
83 ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
86 struct ssh_aes_ctr_ctx *c;
88 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
89 c = xmalloc(sizeof(*c));
90 EVP_CIPHER_CTX_set_app_data(ctx, c);
93 AES_set_encrypt_key(key, ctx->key_len * 8, &c->aes_ctx);
95 memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
100 ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
102 struct ssh_aes_ctr_ctx *c;
104 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
105 memset(c, 0, sizeof(*c));
107 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
113 ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
115 struct ssh_aes_ctr_ctx *c;
117 if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
118 fatal("ssh_aes_ctr_iv: no context");
120 memcpy(c->aes_counter, iv, len);
122 memcpy(iv, c->aes_counter, len);
126 evp_aes_128_ctr(void)
128 static EVP_CIPHER aes_ctr;
130 memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
131 aes_ctr.nid = NID_undef;
132 aes_ctr.block_size = AES_BLOCK_SIZE;
133 aes_ctr.iv_len = AES_BLOCK_SIZE;
134 aes_ctr.key_len = 16;
135 aes_ctr.init = ssh_aes_ctr_init;
136 aes_ctr.cleanup = ssh_aes_ctr_cleanup;
137 aes_ctr.do_cipher = ssh_aes_ctr;
138 aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
139 EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;