[openssh.git] / cipher-ctr.c

/* $OpenBSD: cipher-ctr.c,v 1.9 2006/07/22 20:48:22 stevesk Exp $ */
/*
 * Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include "includes.h"

#include <string.h>

#include <openssl/evp.h>

#include "log.h"
#include "xmalloc.h"

/* compatibility with old or broken OpenSSL versions */
#include "openbsd-compat/openssl-compat.h"

#ifdef USE_BUILTIN_RIJNDAEL
#include "rijndael.h"
#define AES_KEY rijndael_ctx
#define AES_BLOCK_SIZE 16
#define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b)
#define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (char *)a, b, 1)
#else
#include <openssl/aes.h>
#endif

const EVP_CIPHER *evp_aes_128_ctr(void);
void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);

struct ssh_aes_ctr_ctx
{
	AES_KEY		aes_ctx;
	u_char		aes_counter[AES_BLOCK_SIZE];
};

/*
 * increment counter 'ctr',
 * the counter is of size 'len' bytes and stored in network-byte-order.
 * (LSB at ctr[len-1], MSB at ctr[0])
 */
static void
ssh_ctr_inc(u_char *ctr, u_int len)
{
	int i;

	for (i = len - 1; i >= 0; i--)
		if (++ctr[i])	/* continue on overflow */
			return;
}

static int
ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
    u_int len)
{
	struct ssh_aes_ctr_ctx *c;
	u_int n = 0;
	u_char buf[AES_BLOCK_SIZE];

	if (len == 0)
		return (1);
	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
		return (0);

	while ((len--) > 0) {
		if (n == 0) {
			AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
			ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
		}
		*(dest++) = *(src++) ^ buf[n];
		n = (n + 1) % AES_BLOCK_SIZE;
	}
	return (1);
}

static int
ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
    int enc)
{
	struct ssh_aes_ctr_ctx *c;

	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
		c = xmalloc(sizeof(*c));
		EVP_CIPHER_CTX_set_app_data(ctx, c);
	}
	if (key != NULL)
		AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8,
		    &c->aes_ctx);
	if (iv != NULL)
		memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
	return (1);
}

static int
ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
{
	struct ssh_aes_ctr_ctx *c;

	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
		memset(c, 0, sizeof(*c));
		xfree(c);
		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
	}
	return (1);
}

void
ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
{
	struct ssh_aes_ctr_ctx *c;

	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
		fatal("ssh_aes_ctr_iv: no context");
	if (doset)
		memcpy(c->aes_counter, iv, len);
	else
		memcpy(iv, c->aes_counter, len);
}

const EVP_CIPHER *
evp_aes_128_ctr(void)
{
	static EVP_CIPHER aes_ctr;

	memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
	aes_ctr.nid = NID_undef;
	aes_ctr.block_size = AES_BLOCK_SIZE;
	aes_ctr.iv_len = AES_BLOCK_SIZE;
	aes_ctr.key_len = 16;
	aes_ctr.init = ssh_aes_ctr_init;
	aes_ctr.cleanup = ssh_aes_ctr_cleanup;
	aes_ctr.do_cipher = ssh_aes_ctr;
#ifndef SSH_OLD_EVP
	aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
	    EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
#endif
	return (&aes_ctr);
}
Commit	Line	Data
00146caa	1	/* $OpenBSD: cipher-ctr.c,v 1.9 2006/07/22 20:48:22 stevesk Exp $ */
25b66522	2	/*
0a59bd6b	3	* Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
25b66522	4	*
0a59bd6b	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.
25b66522	8	*
0a59bd6b	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.
25b66522	16	*/
25b66522	17	#include "includes.h"
25b66522	18
00146caa	19	#include <string.h>
00146caa	20
25b66522	21	#include <openssl/evp.h>
	22
	23	#include "log.h"
	24	#include "xmalloc.h"
	25
e5146707	26	/* compatibility with old or broken OpenSSL versions */
e5146707	27	#include "openbsd-compat/openssl-compat.h"
0a23d79f	28
e5146707	29	#ifdef USE_BUILTIN_RIJNDAEL
25b66522	30	#include "rijndael.h"
	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)
	35	#else
	36	#include <openssl/aes.h>
	37	#endif
	38
	39	const EVP_CIPHER *evp_aes_128_ctr(void);
	40	void ssh_aes_ctr_iv(EVP_CIPHER_CTX , int, u_char , u_int);
	41
	42	struct ssh_aes_ctr_ctx
	43	{
	44	AES_KEY aes_ctx;
	45	u_char aes_counter[AES_BLOCK_SIZE];
	46	};
	47
	48	/*
	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])
	52	*/
	53	static void
	54	ssh_ctr_inc(u_char *ctr, u_int len)
	55	{
	56	int i;
	57
	58	for (i = len - 1; i >= 0; i--)
	59	if (++ctr[i]) /* continue on overflow */
	60	return;
	61	}
	62
	63	static int
	64	ssh_aes_ctr(EVP_CIPHER_CTX ctx, u_char dest, const u_char *src,
	65	u_int len)
	66	{
	67	struct ssh_aes_ctr_ctx *c;
	68	u_int n = 0;
	69	u_char buf[AES_BLOCK_SIZE];
	70
	71	if (len == 0)
	72	return (1);
	73	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
	74	return (0);
	75
	76	while ((len--) > 0) {
	77	if (n == 0) {
	78	AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
	79	ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
	80	}
	81	(dest++) = (src++) ^ buf[n];
	82	n = (n + 1) % AES_BLOCK_SIZE;
	83	}
	84	return (1);
	85	}
	86
	87	static int
	88	ssh_aes_ctr_init(EVP_CIPHER_CTX ctx, const u_char key, const u_char *iv,
	89	int enc)
	90	{
	91	struct ssh_aes_ctr_ctx *c;
	92
	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);
96	}
97	if (key != NULL)
59d51274	98	AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8,
4e2e5cfd	99	&c->aes_ctx);
25b66522	100	if (iv != NULL)
	101	memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
	102	return (1);
	103	}
	104
	105	static int
	106	ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
	107	{
	108	struct ssh_aes_ctr_ctx *c;
	109
	110	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
	111	memset(c, 0, sizeof(*c));
	112	xfree(c);
	113	EVP_CIPHER_CTX_set_app_data(ctx, NULL);
	114	}
	115	return (1);
	116	}
	117
	118	void
	119	ssh_aes_ctr_iv(EVP_CIPHER_CTX evp, int doset, u_char iv, u_int len)
	120	{
	121	struct ssh_aes_ctr_ctx *c;
	122
	123	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
	124	fatal("ssh_aes_ctr_iv: no context");
	125	if (doset)
	126	memcpy(c->aes_counter, iv, len);
	127	else
	128	memcpy(iv, c->aes_counter, len);
	129	}
	130
	131	const EVP_CIPHER *
	132	evp_aes_128_ctr(void)
	133	{
	134	static EVP_CIPHER aes_ctr;
	135
	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;
0a23d79f	144	#ifndef SSH_OLD_EVP
25b66522	145	aes_ctr.flags = EVP_CIPH_CBC_MODE \| EVP_CIPH_VARIABLE_LENGTH \|
25b66522	146	EVP_CIPH_ALWAYS_CALL_INIT \| EVP_CIPH_CUSTOM_IV;
0a23d79f	147	#endif
25b66522	148	return (&aes_ctr);
25b66522	149	}