cipher-aes.c
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	/*
	* Copyright (c) 2003 Markus Friedl. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "includes.h"

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

	#ifdef USE_BUILTIN_RIJNDAEL
	#include <sys/types.h>

	#include <openssl/evp.h>

	#include <stdarg.h>
	#include <string.h>

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

	#define RIJNDAEL_BLOCKSIZE 16
	struct ssh_rijndael_ctx
	{
	rijndael_ctx r_ctx;
	u_char r_iv[RIJNDAEL_BLOCKSIZE];
	};

	const EVP_CIPHER * evp_rijndael(void);
	void ssh_rijndael_iv(EVP_CIPHER_CTX , int, u_char , u_int);

	static int
	ssh_rijndael_init(EVP_CIPHER_CTX ctx, const u_char key, const u_char *iv,
	int enc)
	{
	struct ssh_rijndael_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) {
	if (enc == -1)
	enc = ctx->encrypt;
	rijndael_set_key(&c->r_ctx, (u_char *)key,
	8*EVP_CIPHER_CTX_key_length(ctx), enc);
	}
	if (iv != NULL)
	memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
	return (1);
	}

	static int
	ssh_rijndael_cbc(EVP_CIPHER_CTX ctx, u_char dest, const u_char *src,
	u_int len)
	{
	struct ssh_rijndael_ctx *c;
	u_char buf[RIJNDAEL_BLOCKSIZE];
	u_char cprev, cnow, plain, ivp;
	int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;

	if (len == 0)
	return (1);
	if (len % RIJNDAEL_BLOCKSIZE)
	fatal("ssh_rijndael_cbc: bad len %d", len);
	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
	error("ssh_rijndael_cbc: no context");
	return (0);
	}
	if (ctx->encrypt) {
	cnow = dest;
	plain = (u_char *)src;
	cprev = c->r_iv;
	for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
	cnow+=RIJNDAEL_BLOCKSIZE) {
	for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
	buf[j] = plain[j] ^ cprev[j];
	rijndael_encrypt(&c->r_ctx, buf, cnow);
	cprev = cnow;
	}
	memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
	} else {
	cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
	plain = dest+len-RIJNDAEL_BLOCKSIZE;

	memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
	for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
	plain-=RIJNDAEL_BLOCKSIZE) {
	rijndael_decrypt(&c->r_ctx, cnow, plain);
	ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
	for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
	plain[j] ^= ivp[j];
	}
	memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
	}
	return (1);
	}

	static int
	ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
	{
	struct ssh_rijndael_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_rijndael_iv(EVP_CIPHER_CTX evp, int doset, u_char iv, u_int len)
	{
	struct ssh_rijndael_ctx *c;

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

	const EVP_CIPHER *
	evp_rijndael(void)
	{
	static EVP_CIPHER rijndal_cbc;

	memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
	rijndal_cbc.nid = NID_undef;
	rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
	rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
	rijndal_cbc.key_len = 16;
	rijndal_cbc.init = ssh_rijndael_init;
	rijndal_cbc.cleanup = ssh_rijndael_cleanup;
	rijndal_cbc.do_cipher = ssh_rijndael_cbc;
	#ifndef SSH_OLD_EVP
	rijndal_cbc.flags = EVP_CIPH_CBC_MODE \| EVP_CIPH_VARIABLE_LENGTH \|
	EVP_CIPH_ALWAYS_CALL_INIT \| EVP_CIPH_CUSTOM_IV;
	#endif
	return (&rijndal_cbc);
	}
	#endif /* USE_BUILTIN_RIJNDAEL */

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