Caesar TC's crack programming achieves recent security development, more and more important for cryptography, although we now use non-symmetric cryptosystems, but at the same time due to some important reasons, the traditional password is still in A large number of uses, such as shift, alternative basic thinking still has no change, I personally think that in the future, we will spend a lot of time to study the cryptography, so that we can promote our e-government, electronics The healthy development of business, the following I want to talk about the decryption of a classical password ---- Caeser password, which is to find its encryption key, thus decrypt, because it is a symmetric password The system, the add-on key is the same, and the following is simple to decrypt the encryption process: ciphertext: c = m k (MOD 26) Decryption process: clear text: m = ck (MOD 26) For detailed procedures, please refer to the relevant information The characteristics of probability statistics are mainly used when cracking, and the probability of e-letters is the largest.
The encrypted program is not to say, the following focuses on the decryption program: I was written in C, and the VC6.0 is down-regulated.
#include "stdio.h" #include "ctype.h" #include "stdlib.h"
Main (int Argc, char * argv []) {
File * fp_ciper, * fp_plain; // Ciphertext and plaintext file pointer char ch_ciper, ch_plain; int i, temp = 0;
