cryptopals/utils.c

35 lines
1 KiB
C

#include "utils.h"
#include <ctype.h>
#include <string.h>
size_t hex_to_bytes(unsigned char *out, const char hex[static 1]) {
for (size_t i = 0; i < strlen(hex); ++i) {
char c = tolower(hex[i]);
unsigned char value;
if (isdigit(c)) {
value = c - '0';
} else {
value = 10 + c - 'a';
}
if (i % 2 == 0) {
value <<= 4;
}
out[i / 2] += value;
}
return strlen(hex) / 2 + strlen(hex) % 2;
}
unsigned char *bytes_to_base64(unsigned char *out,
const unsigned char in[static 1], size_t len) {
static const unsigned char base64_table[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (size_t i = 0; i < len - 2; i += 3) {
size_t j = i / 3 * 4;
out[j] = base64_table[in[i] >> 2];
out[j + 1] = base64_table[((in[i] & 0x03) << 4) | (in[i + 1] >> 4)];
out[j + 2] = base64_table[((in[i + 1] & 0x0f) << 2) | (in[i + 2] >> 6)];
out[j + 3] = base64_table[in[i + 2] & 0x3f];
}
return out;
}