/*-
 * Copyright (c) 2002 Millions Consulting Limited
 * 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 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.
 *
 * $Id: runs.c,v 1.1.1.1 2002/09/11 03:36:00 stacy Exp $
 */

#include <sys/types.h>

/*
 * FIPS 140-1 runs and long runs tests for a random number generator
 *
 * Refrence:
 * http://csrc.nist.gov/publications/fips/fips140-1/fips1401.htm
 */

int runlength(u_char *s, int bits);

/* s should point to a stream of 20,000 bits of muck */
int fips_runs_test(u_char *s)
	{
	int zero_count[6];
	int one_count[6];
	int *count;
	int i;
	int bits;

	for(i = 0; i < 6; i++)
		zero_count[i] = one_count[i] = 0;

	bits = 0;
	while(bits < 20000)
		{
		i = runlength(s, bits);
		if(i < 0)
			{
			count = zero_count;
			i = i * -1;
			}
		else
			count = one_count;
		bits += i;
		if(i > 6) i = 6;
		count[i - 1]++;
		}

	count = zero_count;
	if(!(count[0] >= 2267 && count[0] <= 2733)) return 0;
	if(!(count[1] >= 1079 && count[1] <= 1421)) return 0;
	if(!(count[2] >= 502 && count[2] <= 748)) return 0;
	if(!(count[3] >= 223 && count[3] <= 402)) return 0;
	if(!(count[4] >= 90 && count[4] <= 223)) return 0;
	if(!(count[5] >= 90 && count[5] <= 223)) return 0;

	count = one_count;
	if(!(count[0] >= 2267 && count[0] <= 2733)) return 0;
	if(!(count[1] >= 1079 && count[1] <= 1421)) return 0;
	if(!(count[2] >= 502 && count[2] <= 748)) return 0;
	if(!(count[3] >= 223 && count[3] <= 402)) return 0;
	if(!(count[4] >= 90 && count[4] <= 223)) return 0;
	if(!(count[5] >= 90 && count[5] <= 223)) return 0;

	return 1;
	}

int fips_long_run_test(u_char *s)
	{
	int r;
	int bits;
	int i;

	r = bits = 0;
	while(bits < 20000)
		{
		i = runlength(s, bits);
		if(i < 0) i = i * -1;
		if(i >= 34)
			r++;

		bits += i;
		}

	if(r == 0) return 1;
	else return 0;
	}


int runlength(u_char *s, int bits)
	{
	int count;
	int zero;
	u_char b, B, mask;
	int byte;
	int match;
	int tbits;

	tbits = bits;
	/* get the index of the byte and bit where we left off */
	byte = bits / 8;
	bits = bits % 8;

	mask = 0x80 >> bits;
	B = *(s+byte);
	b = B & mask;

	zero = (b == 0);
	count = 0;

	do
		{
		count++;
		tbits++;
		mask = mask >> 1;
		if(mask == 0)
			{
			byte++;
			B = *(s+byte);
			mask = 0x80;
			}
		b = B & mask;

		match = zero ? (b == 0) : (b > 0);
		}
	while(match && tbits < 20000);

	if(zero) count *= -1;

	return count;
	}