/* SN3 implementation. Public Domain. No warranty of any kind. */
/* Author: Simeon Maltchev, smaltchev@yahoo.com, 2002 - 2003 */

#include <stdio.h>
#include <string.h>

typedef unsigned long int u32;

#define TABLE_SIZE 64
#define SBOX_SIZE (3 * TABLE_SIZE)
#define INDEX_MASK (TABLE_SIZE - 1)

#define rotl(a, b) (((a) << ((b) & 31)) | ((a) >> (32 - ((b) & 31))))

u32 keystream[SBOX_SIZE];
u32 seed[SBOX_SIZE];

char *simple_key = "abcdefgh";

void sn3();
void init_seed(char *key, u32 key_len);
void print_keystream();

int main()
{
	init_seed(simple_key, strlen(simple_key));

	sn3();
	print_keystream();

	sn3();
	print_keystream();

	return 0;
}

/* Call this function to generate 192 pseudo-random 32-bit values. 
   Output is accessible through "keystream" global variable. */
void sn3()
{
	u32 *v1, *v2, *v3, *temp, *kstream;
	u32 t1, t2, t3, i, m, n;
	static u32 j = 0;
	
	kstream = (u32 *) keystream;
    v1 = seed;
	v2 = v1 + TABLE_SIZE;
	v3 = v2 + TABLE_SIZE;
	for (n = 0; n < 3; n++)
	{
		for (i = 0; i < TABLE_SIZE; i++)
		{
			t1 = v1[i];
			t2 = v2[j];
			m  = t1 & INDEX_MASK;
			t3 = v3[m];
			
			*kstream++ = t1 ^ t2 ^ t3;

			v1[i] = rotl(t1, 1)  ^ t2;
			v2[j] = rotl(t2, 5)  ^ t3 ^ 0x8c591ca1;
			v3[m] = rotl(t3, 17) ^ t1 ^ 0xab8ec254;

			j = (t1 >> 8) & INDEX_MASK;
		}
		
		temp = v1;
		v1   = v2;
		v2   = v3;
		v3   = temp;
	}    
}

void init_seed(char *key, u32 key_len)
{
	u32 i, j;
	char *char_seed = (char *) seed;

	for (i = j = 0; i < SBOX_SIZE*sizeof(u32); i++, j++)
	{
		if (j == key_len)
			j = 0;
		char_seed[i] = key[j];
	}

	sn3();
	for (i = 0; i < SBOX_SIZE; i++)
		seed[i] = rotl(seed[i], 19) ^ keystream[i];
}

void print_keystream()
{
	u32 i;

	for (i = 1; i <= SBOX_SIZE; i++) {
		printf("%08x\t", keystream[i - 1]);
		if (i % 4 == 0)
			printf("\n");
	}
	printf("\n\n");
}