/*
 * Copyright (c) 2006-2007 Christophe Devine
 * 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.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
 */
/*
 *  The MD2 algorithm was designed by Ron Rivest in 1989.
 *
 *  http://www.ietf.org/rfc/rfc1115.txt
 *  http://www.ietf.org/rfc/rfc1319.txt
 */

#include "cryb/impl.h"

#include <stdint.h>
#include <string.h>

#include <cryb/md2.h>

static const uint8_t PI_SUBST[256] =
{
    0x29, 0x2E, 0x43, 0xC9, 0xA2, 0xD8, 0x7C, 0x01, 0x3D, 0x36,
    0x54, 0xA1, 0xEC, 0xF0, 0x06, 0x13, 0x62, 0xA7, 0x05, 0xF3,
    0xC0, 0xC7, 0x73, 0x8C, 0x98, 0x93, 0x2B, 0xD9, 0xBC, 0x4C,
    0x82, 0xCA, 0x1E, 0x9B, 0x57, 0x3C, 0xFD, 0xD4, 0xE0, 0x16,
    0x67, 0x42, 0x6F, 0x18, 0x8A, 0x17, 0xE5, 0x12, 0xBE, 0x4E,
    0xC4, 0xD6, 0xDA, 0x9E, 0xDE, 0x49, 0xA0, 0xFB, 0xF5, 0x8E,
    0xBB, 0x2F, 0xEE, 0x7A, 0xA9, 0x68, 0x79, 0x91, 0x15, 0xB2,
    0x07, 0x3F, 0x94, 0xC2, 0x10, 0x89, 0x0B, 0x22, 0x5F, 0x21,
    0x80, 0x7F, 0x5D, 0x9A, 0x5A, 0x90, 0x32, 0x27, 0x35, 0x3E,
    0xCC, 0xE7, 0xBF, 0xF7, 0x97, 0x03, 0xFF, 0x19, 0x30, 0xB3,
    0x48, 0xA5, 0xB5, 0xD1, 0xD7, 0x5E, 0x92, 0x2A, 0xAC, 0x56,
    0xAA, 0xC6, 0x4F, 0xB8, 0x38, 0xD2, 0x96, 0xA4, 0x7D, 0xB6,
    0x76, 0xFC, 0x6B, 0xE2, 0x9C, 0x74, 0x04, 0xF1, 0x45, 0x9D,
    0x70, 0x59, 0x64, 0x71, 0x87, 0x20, 0x86, 0x5B, 0xCF, 0x65,
    0xE6, 0x2D, 0xA8, 0x02, 0x1B, 0x60, 0x25, 0xAD, 0xAE, 0xB0,
    0xB9, 0xF6, 0x1C, 0x46, 0x61, 0x69, 0x34, 0x40, 0x7E, 0x0F,
    0x55, 0x47, 0xA3, 0x23, 0xDD, 0x51, 0xAF, 0x3A, 0xC3, 0x5C,
    0xF9, 0xCE, 0xBA, 0xC5, 0xEA, 0x26, 0x2C, 0x53, 0x0D, 0x6E,
    0x85, 0x28, 0x84, 0x09, 0xD3, 0xDF, 0xCD, 0xF4, 0x41, 0x81,
    0x4D, 0x52, 0x6A, 0xDC, 0x37, 0xC8, 0x6C, 0xC1, 0xAB, 0xFA,
    0x24, 0xE1, 0x7B, 0x08, 0x0C, 0xBD, 0xB1, 0x4A, 0x78, 0x88,
    0x95, 0x8B, 0xE3, 0x63, 0xE8, 0x6D, 0xE9, 0xCB, 0xD5, 0xFE,
    0x3B, 0x00, 0x1D, 0x39, 0xF2, 0xEF, 0xB7, 0x0E, 0x66, 0x58,
    0xD0, 0xE4, 0xA6, 0x77, 0x72, 0xF8, 0xEB, 0x75, 0x4B, 0x0A,
    0x31, 0x44, 0x50, 0xB4, 0x8F, 0xED, 0x1F, 0x1A, 0xDB, 0x99,
    0x8D, 0x33, 0x9F, 0x11, 0x83, 0x14
};

/*
 * MD2 context setup
 */
void md2_init( md2_ctx *ctx )
{
    memset( ctx, 0, sizeof( md2_ctx ) );
}

static void md2_process( md2_ctx *ctx )
{
    int i, j;
    uint8_t t = 0;

    for( i = 0; i < 16; i++ )
    {
	ctx->state[i + 16] = ctx->buffer[i];
	ctx->state[i + 32] =
	    (uint8_t)( ctx->buffer[i] ^ ctx->state[i]);
    }

    for( i = 0; i < 18; i++ )
    {
	for( j = 0; j < 48; j++ )
	{
	    ctx->state[j] = (uint8_t)
	       ( ctx->state[j] ^ PI_SUBST[t] );
	    t  = ctx->state[j];
	}

	t = (uint8_t)( t + i );
    }

    t = ctx->cksum[15];

    for( i = 0; i < 16; i++ )
    {
	ctx->cksum[i] = (uint8_t)
	   ( ctx->cksum[i] ^ PI_SUBST[ctx->buffer[i] ^ t] );
	t  = ctx->cksum[i];
    }
}

/*
 * MD2 process buffer
 */
void md2_update( md2_ctx *ctx, const void *input, int ilen )
{
    int fill;

    while( ilen > 0 )
    {
	if( ctx->left + ilen > 16 )
	    fill = 16 - ctx->left;
	else
	    fill = ilen;

	memcpy( ctx->buffer + ctx->left, input, fill );

	ctx->left += fill;
	input += fill;
	ilen  -= fill;

	if( ctx->left == 16 )
	{
	    ctx->left = 0;
	    md2_process( ctx );
	}
    }
}

/*
 * MD2 final digest
 */
void md2_final( md2_ctx *ctx, uint8_t *output )
{
    int i;
    uint8_t x;

    x = (uint8_t)( 16 - ctx->left );

    for( i = ctx->left; i < 16; i++ )
	ctx->buffer[i] = x;

    md2_process( ctx );

    memcpy( ctx->buffer, ctx->cksum, sizeof ctx->cksum );
    md2_process( ctx );

    memcpy( output, ctx->state, MD2_DIGEST_LEN );
}

/*
 * output = MD2( input buffer )
 */
void md2_complete( const void *input, int ilen, uint8_t *output )
{
    md2_ctx ctx;

    md2_init( &ctx );
    md2_update( &ctx, input, ilen );
    md2_final( &ctx, output );

    memset( &ctx, 0, sizeof( md2_ctx ) );
}

digest_algorithm md2_digest = {
	.name			 = "md2",
	.contextlen		 = sizeof(md2_ctx),
	.blocklen		 = MD2_BLOCK_LEN,
	.digestlen		 = MD2_DIGEST_LEN,
	.init			 = (digest_init_func)md2_init,
	.update			 = (digest_update_func)md2_update,
	.final			 = (digest_final_func)md2_final,
	.complete		 = (digest_complete_func)md2_complete,
};