xor encryption inopérante
bonjour,
au cvours de mes ballades on line j'ai trouvé un challenge qui m'a intrigué :
Citation:
XOR Encryption (which most people will tell you is not really encryption at all) is performed by taking a key and xoring each byte in a file with the each byte in the key. This is generally performed by moving through the key a character at a time, and repeating when the end is reached.
Take this file and xor it with the string secret (restart at s when you come to t).
Then exchange the following byte values in the file:
# 23 with 0
# 78 with 66
# 36 with 144
and the other way round!! i.e. 0 with 23
Save the result as a file and rename it to .jpg Open it in a picture viewer and the resulting message is your solution.
j'ai codé ça :
Code:
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| #include <iostream>
#include <fstream>
int main() {
std::ifstream f("data.bin",std::ios::binary);
std::ofstream out("sortie.jpg",std::ios::binary);
std::string key("secret");
int i=0;
if (f.is_open() && out.is_open()) {
int y=0;
unsigned char c=f.get() ^ key[y];
while(f.eof()!=true) {
(y == key.size())? y=0 :y++;
switch(c) {
case 0x0: c=0x17; break; // 0 <-> 23
case 0x42: c=0x4e; break; // 66 <-> 78
case 0x90: c=0x24; break; // 144 <-> 36
case 0x17: c=0x0; break;
case 0x4e: c=0x42; break;
case 0x24: c=0x90; break;
default:break;
}
out << c;
c=f.get() ^ key[y];
}
}
return 1;
} |
Mais ça ne marche pas. où est le problème ?
