ref: 3.5.0002 MaraDNS/rng/make_32bit_tables.c -rw-r--r-- 3.9 KiB
db09084f — Sam Trenholme MaraDNS release 3.5.0002 7 months ago
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```/* This is a program which calculates and makes the tables used by
the RNG core
Written by Sam Trenholme
* Copyright (c) 2002,2003 Sam Trenholme
*
* TERMS
*
* 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 'as is' with no guarantees of correctness or
* fitness for purpose.
*/

#include <stdio.h>
#include <stdlib.h>

/* Multiply two elements together for any GF(2^n), where n is less than 30
Input: The two elements to multiply together, the degree to
multiply by, the reducing polynomial for the degree in question
Output: The product of the two elements
*/
int gmul(int i1, int i2, int degree, int field) {
int result = 0;
int counter;
int hibit = 1;
for(counter = 0; counter < degree; counter++)
hibit <<= 1;
for(counter = 0; counter < degree; counter++) {
if((i2 & 1) == 1)
result ^= i1;
i2 >>= 1;
i1 <<= 1;
if((i1 & hibit) == hibit)
i1 ^= field;
}
return result;
}

/* Multiply two elements together in a galois field of 2^8
Input: The two elements to multiply together
Output: The product of the two elements
*/
int mul(int i1, int i2) {
return gmul(i1,i2,8,0x11b);
}

/* Multiply two elements together in the field of 2^4
Input: The two elements to multiply together
Output: The product of the two elements
*/
unsigned char mul_4(unsigned char i1, unsigned char i2) {
return gmul(i1,i2,4,0x13);
}

/* sbox: calculate, on the fly, the sbox
Input: The byte to calculate the sbox for
Output: The sbox for the byte in question
*/
unsigned char sbox(unsigned char in) {
/* The sboxes */
unsigned char rbox = {0x7,0xc,0xb,0xd,0xe,0x4,0x9,0xf,
0x6,0x3,0x8,0xa,0x2,0x5,0x1,0x0};
unsigned char ebox,iebox;
/* The two nibbles of this byte */
unsigned char lnib, rnib, ivalue;
int counter;

/* Generate the ebox */
ebox = 1;
for(counter = 1; counter < 15; counter++)
ebox[counter] = mul_4(ebox[counter - 1],0xb) & 0xf;
ebox[0xf] = 0;

/* Generate the inverse ebox */
for(counter = 0; counter < 16; counter++)
iebox[ebox[counter]] = counter;

lnib = (in & 0xf0) >> 4;
rnib = in & 0x0f;
lnib = ebox[lnib];
rnib = iebox[rnib];
ivalue = lnib ^ rnib;
ivalue = rbox[ivalue];
lnib ^= ivalue;
rnib ^= ivalue;
lnib = ebox[lnib];
rnib = iebox[rnib];
return (lnib << 4) | rnib;
}

/* Make one table: Make a single one of the four tables
Input: four multiply constants
Output: Displays table on stdout
*/

void one_en_table(int m1, int m2, int m3, int m4) {
int counter;
unsigned char s;
for(counter = 0; counter < 256; counter++) {
if(counter % 4 == 0)
printf("\n");
s = sbox(counter);
printf("0x%02x%02x%02x%02xU, ",
mul(s,m1),mul(s,m2),mul(s,m3),mul(s,m4));
}
printf("\n};\n");
}

int main() {
int a = {19,77,6,16};
printf("/* This file is automatically generated by the program ");
printf("make_32bit_tables.c */\n\n");
printf("static const u32 Te0 = {");
one_en_table(a,a,a,a);
printf("static const u32 Te1 = {");
one_en_table(a,a,a,a);
printf("static const u32 Te2 = {");
one_en_table(a,a,a,a);
printf("static const u32 Te3 = {");
one_en_table(a,a,a,a);
printf("static const u32 Te4 = {");
one_en_table(1,1,1,1);
exit(0);
}
```