95 lines
2.0 KiB
C
95 lines
2.0 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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#include <string.h>
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bool block_eq(uint8_t const * const a, uint8_t const * const b) {
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/* Compares two blocks, return true if they are identical, else
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false */
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return !(memcmp(a, b, 16));
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}
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#ifdef HOST_BUILD
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void block_print(char const * const label,
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uint8_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[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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#endif /* HOST_BUILD */
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void block_xor(uint8_t *dest, uint8_t * const a, uint8_t * const b) {
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for (uint_fast8_t i = 0; i < 4; i++) {
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*((uint32_t *)dest+i) = *((uint32_t *)a+i) ^ *((uint32_t *)b+i);
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}
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return;
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}
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void block_shiftr(uint8_t *dest, uint8_t * const a, uint_fast8_t num) {
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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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dest[i] = a[i] >> n;
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if (i != 0) {
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dest[i] |= (a[i-1] << (8 - n));
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}
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}
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if (num - n != 0) {
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block_shiftr(dest, dest, num - n);
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}
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return;
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}
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void block_shiftl(uint8_t *dest, uint8_t * const a, uint_fast8_t num) {
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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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dest[i] = a[i] << n;
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if (i != 15) {
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dest[i] |= (a[i+1] >> (8 - n));
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}
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}
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if (num - n != 0) {
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block_shiftl(dest, dest, num - n);
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}
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return;
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}
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void block_incr(uint8_t *in) {
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for (int_fast8_t i = 15; i > 0 ; i--) {
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uint8_t prev = in[i];
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in[i] += 1;
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if (in[i] > prev) {
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/* No overflow, changes propagate no further */
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break;
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}
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}
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return;
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}
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void block_decr(uint8_t *in) {
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for (int_fast8_t i = 15; i > 0 ; i--) {
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uint8_t prev = in[i];
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in[i] -= 1;
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if (in[i] < prev) {
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/* No overflow, changes propagate no further */
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break;
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}
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}
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return;
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}
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