72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
/* Utility functions for manipulating block_t structures; 128bit
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blocks of data for AES & CMAC */
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#include "block.h"
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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bool block_cmp(block_t const * const a, block_t const * const b) {
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for (uint_fast8_t i = 0; i < 4; i++) {
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if (a->ui32[i] != b->ui32[i]) {
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return false;
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}
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}
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return true;
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}
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void block_print(char const * const label,
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block_t const * const b) {
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if (label != NULL) {
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printf("\n%s: ", label);
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} else {
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printf("\n");
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}
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for(int i = 0; i < 16; i++) {
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printf("%.2x", b->ui8[i]);
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if (!((i+1) % 4)) {
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printf(" ");
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}
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}
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printf("\n");
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return;
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}
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block_t block_xor(block_t const * const a, block_t const * const b) {
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block_t c;
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for (uint_fast8_t i = 0; i < 4; i++) {
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c.ui32[i] = a->ui32[i] ^ b->ui32[i];
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}
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return c;
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}
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block_t block_shiftr(block_t const * const a, uint_fast8_t const num) {
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block_t c;
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uint_fast8_t n = (num <= 8 ? num : 8);
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for (int_fast8_t i = 15; i >= 0; i--) {
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/* Shift right from LSB to MSB */
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c.ui8[i] = a->ui8[i] >> n;
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if (i != 0) {
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/* If theres a more significant uint32, we need to pull in its lsb */
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c.ui8[i] |= (a->ui8[i-1] << (8 - n));
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}
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}
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return (num - n == 0 ? c : block_shiftr(&c, num - n));
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}
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block_t block_shiftl(block_t const * const a, uint_fast8_t const num) {
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/* Shifts block b right by num bits (where num <= 32) */
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block_t c;
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uint_fast8_t n = (num <= 8 ? num : 8);
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for (int_fast8_t i = 0; i < 16; i++) {
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/* Shift right from LSB to MSB */
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c.ui8[i] = a->ui8[i] << n;
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if (i != 15) {
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/* If theres a less significant uint32, we need to pull in its msb */
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c.ui8[i] |= (a->ui8[i+1] >> (8 - n));
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}
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}
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return (num - n == 0 ? c : block_shiftl(&c, num - n));
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}
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