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f3ndot/key_schedule_test.c

Last active December 12, 2015 03:18
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An ugly proof-of-concept for removing the 8th bit of every byte in a 9-byte key and combining the results into an 8-byte key schedule.
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key_schedule_test.c
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define BYTETOBINARYPATTERN "%d%d%d%d%d%d%d%d"
#define BYTETOBINARY(byte) \
(byte & 0x80 ? 1 : 0), \
(byte & 0x40 ? 1 : 0), \
(byte & 0x20 ? 1 : 0), \
(byte & 0x10 ? 1 : 0), \
(byte & 0x08 ? 1 : 0), \
(byte & 0x04 ? 1 : 0), \
(byte & 0x02 ? 1 : 0), \
(byte & 0x01 ? 1 : 0)
int main(int argc, char **argv) {
int i;
unsigned char str[10] = "MyKeyGood";
unsigned char str2[8] = { 0x00 };
printf("Key: ");
for (i = 0; i < 9; ++i) {
printf("%c", str[i]);
}
putchar('\n');
for (i = 0; i < 9; ++i) {
printf("0x%.2X ", str[i]);
}
putchar('\n');
for (i = 0; i < 9; ++i) {
printf (BYTETOBINARYPATTERN" ", BYTETOBINARY(str[i]));
}
putchar('\n');
putchar('\n');
putchar('\n');
for (i = 0; i < 8; ++i) {
printf ("START: "BYTETOBINARYPATTERN" \n", BYTETOBINARY(str[i]));
// shift-left entire byte by i bits because of previous byte taking i bits of this one
str[i] = str[i] << i;
printf ("SHIFT LF: "BYTETOBINARYPATTERN" (Shift Left %i Bits)\n", BYTETOBINARY(str[i]), i);
// Remove/Mask out the last i+1 bits (i because of previous + 1 new bit to be removed)
str[i] = str[i] >> i+1;
str[i] = str[i] << i+1;
printf ("REM LAST: "BYTETOBINARYPATTERN" (Moved Right-Left %i Bits)\n", BYTETOBINARY(str[i]), (i+1));
// shift next byte's first-most i+1 bits to the right-most (position 8)
unsigned char temp = str[i+1] >> (8 - (i+1));
printf ("NXT SHFT: "BYTETOBINARYPATTERN" (Shift Right %i Bits)\n", BYTETOBINARY(temp), (8 - (i+1)));
// combine/bitwise-OR the result
str2[i] = str[i] | temp;
printf ("BOR BOTH: "BYTETOBINARYPATTERN" \n", BYTETOBINARY(str2[i]));
printf("---------------\n");
}
// printf("\n\nMasked out 8th bit of every byte in key:\n-----------");
printf("\n\nKey: ");
for (i = 0; i < 8; ++i) {
printf("%c", str2[i]);
}
putchar('\n');
for (i = 0; i < 8; ++i) {
printf("0x%.2X ", str2[i]);
}
putchar('\n');
for (i = 0; i < 8; ++i) {
printf (BYTETOBINARYPATTERN" ", BYTETOBINARY(str2[i]));
}
putchar('\n');
putchar('\n');
return 0;
}
// 01001101 01111001 01001011 01100101 01111001 01000111 01101111 01101111 01100100
// 01001100 11110001 00101011 00100111 10001000 11011011 10110111 01100100
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