95 lines
2.4 KiB
C
95 lines
2.4 KiB
C
#include "../../lib/md2_impls/md2_2.h"
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#include "../../lib/md2_impls/md2_common.h"
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void process_block_hash(uint8_t block[16], uint8_t messageDigestBuf[48]) {
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for (int j = 0; j < 16; j++) {
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messageDigestBuf[16 + j] = block[j];
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messageDigestBuf[32 + j] = (messageDigestBuf[16 + j] ^ messageDigestBuf[j]);
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}
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u_int8_t t = 0;
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for (int j = 0; j < 18; j++) {
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for (int k = 0; k < 48; k++) {
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t = messageDigestBuf[k] = messageDigestBuf[k] ^ MD2_PI_SUBST[t];
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}
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t = (t + j) % 256;
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}
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}
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void process_block_checksum(uint8_t block[16], uint8_t checksum[16],
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uint8_t* l) {
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for (int j = 0; j < 16; j++) {
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u_int8_t c = block[j];
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// reference is wrong. It says: Set C[j] to S[c xor L]. But it should be:
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(*l) = checksum[j] ^= MD2_PI_SUBST[c ^ (*l)];
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}
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}
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void apply_padding(size_t len, uint8_t buf[16]) {
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int paddingNeeded = 16 - (len % 16);
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uint8_t originalPadding = paddingNeeded;
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len += paddingNeeded;
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while (paddingNeeded > 0) {
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buf[len - paddingNeeded] = originalPadding;
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paddingNeeded--;
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}
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}
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void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
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FILE* file;
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struct stat file_stat;
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if (!open_file((char*)buf, &file, &file_stat)) {
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return;
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}
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// === step 3 ===
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uint8_t* messageDigestBuf = calloc(48, sizeof(uint8_t));
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if (messageDigestBuf == NULL) {
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return;
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}
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// === step 4 ===
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uint8_t l = 0;
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uint8_t* checksum = calloc(16, sizeof(uint8_t));
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if (checksum == NULL) {
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return;
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}
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uint8_t* data = malloc(16);
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if (data == NULL) {
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return;
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}
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size_t bytes_left_to_read = file_stat.st_size;
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size_t bytes_left_to_process = 0;
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while (bytes_left_to_read != 0) {
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bytes_left_to_process = bytes_left_to_read >= 16 ? 16 : bytes_left_to_read;
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size_t size = fread(data, 1, bytes_left_to_process, file);
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if (size == 0 || ferror(file) || feof(file)) {
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if (errno == 0) errno = EIO;
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return;
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}
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process_block_checksum(data, checksum, &l);
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process_block_hash(data, messageDigestBuf);
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bytes_left_to_read -= bytes_left_to_process;
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};
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fclose(file);
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apply_padding(bytes_left_to_process % 16, data);
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process_block_checksum(data, checksum, &l);
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process_block_hash(data, messageDigestBuf);
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process_block_hash(checksum, messageDigestBuf);
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memcpy(out, messageDigestBuf, 16);
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free(data);
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free(messageDigestBuf);
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free(checksum);
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}
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