/*
 * 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];
};

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,
    size_t 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));
                free(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 */