Hello,
I have tried to use crypto++ to get the same result as mcrypt for a
simple CFB crypto. The reason is I am trying to write a new client for
an existing server that use mcrypt, and mcrypt is not "easily"
available for windows.
The result from mcrypt is:
0xa7, 0x8f, 0x88, 0x4e, ...
Where-as the result from crypto++ is:
0xa7, 0x44, 0x24, 0x6e, ...
As you can see the first byte is the same but the following ones are
not. I have seen another post on the list regarding a similar issue
but there was no solution. I am thinking it might be related to some
issues with block-size or some such but I am not an expert on
cryptography so I hope that someone here might be able to help me with
this. I have also tried this with DES/3DES with the exact same result
(ie. first char correct, the rest are not).
// Michael Medin
The code I use is:
#include <stdio.h>
#include <mcrypt.h>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <crypto++/cryptlib.h>
#include <crypto++/modes.h>
#include <crypto++/des.h>
#include <crypto++/aes.h>
#include <crypto++/filters.h>
#include <mcrypt.h>
unsigned char key[] = {0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
0x39, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x30,
0x31, 0x32}; // 12345678901234567890123456789012
unsigned char iv[] = {0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
0x39, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36}; // 1234567890123456
unsigned char plain[] = {0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x77,
0x6f, 0x72, 0x6c, 0x64}; // hello world
void print_it(char *title, unsigned char* buff, int len) {
int i;
printf("unsigned char %s[] = {", title);
for (i=0;i<len-1;i++) {
printf("0x%x, ", (unsigned char)buff[i]);
}
printf("0x%x", (unsigned char)buff[len-1]);
printf("} // %s\n", buff);
}
void testCryptoPP() {
CryptoPP::CFB_Mode< CryptoPP::AES >::Encryption encryptor(key,
sizeof(key), iv, sizeof(iv));
unsigned char ciphertext[100];
for(int x=0;x<sizeof(plain);x++) {
encryptor.ProcessData(&ciphertext[x], (unsigned
char*)&plain[x], 1);
ciphertext[x+1] = 0;
}
print_it("plain", plain, sizeof(plain));
print_it("crypto", ciphertext, sizeof(plain));
}
void testMCrypt() {
MCRYPT td;
td = mcrypt_module_open(MCRYPT_RIJNDAEL_128,NULL,"cfb",NULL);
int iv_size = mcrypt_enc_get_iv_size(td);
printf("iv size: %d (%d)\n", iv_size, sizeof(iv));
int key_size = mcrypt_enc_get_key_size(td);
printf("key size: %d (%d)\n", key_size, sizeof(key));
mcrypt_generic_init(td,key,key_size,iv);
print_it("plain", plain, sizeof(plain));
for(int x=0;x<sizeof(plain);x++)
mcrypt_generic(td,&plain[x],1);
print_it("mcrypt", plain, sizeof(plain));
}
int main(int argv, char *argc[]) {
testCryptoPP();
testMCrypt();
}
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