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feat: implement step 2: checksum

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This commit is contained in:
Thomas Florian 2022-06-29 15:53:46 +02:00
parent eeb4164610
commit 3940ee3a21
1 changed files with 37 additions and 3 deletions
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40
Implementierung/src/md2.c
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@ -3,6 +3,27 @@
// The file "testfile" should lead to this hash:
// fc982e558db259f298b43cd4c1241c66
// Source: https://datatracker.ietf.org/doc/html/rfc1319
static unsigned char PI_SUBST[256] = {
41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6,
19, 98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188,
76, 130, 202, 30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24,
138, 23, 229, 18, 190, 78, 196, 214, 218, 158, 222, 73, 160, 251,
245, 142, 187, 47, 238, 122, 169, 104, 121, 145, 21, 178, 7, 63,
148, 194, 16, 137, 11, 34, 95, 33, 128, 127, 93, 154, 90, 144, 50,
39, 53, 62, 204, 231, 191, 247, 151, 3, 255, 25, 48, 179, 72, 165,
181, 209, 215, 94, 146, 42, 172, 86, 170, 198, 79, 184, 56, 210,
150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241, 69, 157,
112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2, 27,
96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197,
234, 38, 44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65,
129, 77, 82, 106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123,
8, 12, 189, 177, 74, 120, 136, 149, 139, 227, 99, 232, 109, 233,
203, 213, 254, 59, 0, 29, 57, 242, 239, 183, 14, 102, 88, 208, 228,
166, 119, 114, 248, 235, 117, 75, 10, 49, 68, 80, 180, 143, 237,
31, 26, 219, 153, 141, 51, 159, 17, 131, 20};
void printBuf(size_t len, uint8_t buf[len]) {
for (int i = 0; i < len; i++) {
printf("'%lx',", buf[i]);
@ -10,7 +31,17 @@ void printBuf(size_t len, uint8_t buf[len]) {
printf("\n");
}
void md2_checksum(size_t len, uint8_t* buf) {}
void md2_checksum(size_t len, uint8_t* buf) {
uint8_t l = 0;
for (int i = 0; i < len / 16; i++) {
for (int j = 0; j < 16; j++) {
u_int8_t c = buf[i * 16 + j];
buf[len + j] = PI_SUBST[c ^ l];
l = buf[len + j];
}
}
}
void md2_hash(size_t len, const uint8_t buf[len], uint8_t out[16]) {
// add padding
@ -20,7 +51,7 @@ void md2_hash(size_t len, const uint8_t buf[len], uint8_t out[16]) {
printf("len: %d\n", len);
uint8_t* newBuf = malloc(len);
uint8_t* newBuf = malloc(len + 16); // 16 = Checksum
memcpy(newBuf, buf, len - paddingNeeded);
newBuf[4] = 'f';
@ -28,8 +59,11 @@ void md2_hash(size_t len, const uint8_t buf[len], uint8_t out[16]) {
newBuf[len - paddingNeeded] = originalPadding;
paddingNeeded--;
}
printBuf(len, newBuf);
md2_checksum(len, newBuf);
printBuf(len + 16, newBuf);
free(newBuf);
}