AES128 encrypt/decrypt using gcrypt in c++ - libgcrypt

Question

i couldnt find a working good example so ive created one
you can change mykey ,and make the iv random using one of the gcrypt function.
sample
#include <iostream>
#include <gcrypt.h>
typedef unsigned char byte;
using namespace std;
#define BLOCK 16
const byte mykey []= {0x2d,0x65,0x20,0x74,0x69,0x6D,0x65,0x20,0x66,0x6F,0x72};
const byte end1[] ={0x0};
const byte message [] = {0x4E,0x6F,0x77,0x20,0x69,0x73,0x20,0x74,0x68,0x65,0x20,0x74,0x69,0x6D,0x65,0x20,0x66,0x6F,0x72,0x20,0x61,0x6C,0x6C,0x20,0x67,0x6F,0x6F,0x64,0x20,0x6D,0x65,0x6E,0x20,0x74,0x6F,0x20,0x63,0x6F,0x6D,0x65,0x20,0x74,0x6F,0x20,0x74,0x68,0x65,0x20,0x61,0x69,0x64,0x65,0x20,0x6F,0x66,0x20,0x74,0x68,0x65,0x20,0x63,0x6F,0x75,0x6E,0x74,0x72,0x79,0x2E,0x00 };
const byte end[] = {0x00};
// encrypt
// Encrypt data in BLOCK in place if EDFLAG is zero; otherwise decrypt
// block in place.
#define roundup(x,n) \
n *((sizeof(x))/n + (((sizeof(x))%n)+1)/(((sizeof(x))%n)+1))
void verify ( gcry_error_t err, const char* msg ) {
if (err) {
cout << msg << " " << gcry_strsource(err)<< " / " << gcry_strerror(err) << endl;
exit(1);
}
}
/* PROGMA BEGIN
* encrypt decrypt
* using the GCRYPT */
int main (){
gcry_error_t err = 0;
// init the lib ..
if (!gcry_check_version (GCRYPT_VERSION))
{ cout << "gcrypt: library version mismatch" << endl; exit(1); }
err = gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN);
err |= gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0);
err |= gcry_control (GCRYCTL_RESUME_SECMEM_WARN);
err |= gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
verify (err,"gcrypt: failed initialization");
//init the operation mode
#define GCRY_CIPHER GCRY_CIPHER_AES128
#define GCRY_MODE GCRY_CIPHER_MODE_ECB
//#define GCRY_FLAG GCRY_CIPHER_ENABLE_SYNC
#define GCRY_FLAG 0
gcry_cipher_hd_t handle;
err = gcry_cipher_open( &handle, GCRY_CIPHER, GCRY_MODE, GCRY_FLAG);
verify ( err, "gcry_cipher_open" ) ;
byte iv[BLOCK];
memset(iv,0x23,BLOCK); // just for example, we should get it from the cipher word, first 16 bytes
memset(iv, 0x89 , BLOCK -4);
err = gcry_cipher_setiv(handle,iv,BLOCK);
verify( err, "set iv ");
cout <<"iv seT: "<< BLOCK << ":"<< iv << endl;
err = gcry_cipher_setkey(handle, mykey, sizeof(mykey));
verify( err, "set KeY ");
cout << "KeY set: "<< sizeof(mykey) <<":";// << mykey << endl;
for ( int i = 0 ; i <sizeof(mykey) ; ++i ) cout << mykey[i];
cout << endl;
// init done
// in = message
// out - new
unsigned char out[ roundup(message,BLOCK) ];
memset(out,0,roundup(message,BLOCK) );
//memcpy( out, message, sizeof(message));
size_t outsize = sizeof(out);
err = gcry_cipher_encrypt( handle, out, outsize, message, outsize);
verify( err, "encrypt " );
cout <<endl<< "encrypt in: " << sizeof(message) << ":" << message << endl ;
cout << "encrypt out: " << outsize << ":"<< out << endl<<endl;
unsigned char decrypt[roundup(out,BLOCK)]; // to out
memset(decrypt, 0 , roundup(out,BLOCK) );
size_t dsize= sizeof(decrypt);
err = gcry_cipher_decrypt( handle, decrypt, dsize, out, outsize);
verify( err, "decrypt " );
cout << "decrypt in: " << outsize << ":";
for ( int i = 0 ; i < outsize ; ++i ) cout << out[i];
cout << endl;
cout << "decrypt out: " << dsize << ":"<< decrypt << endl;
gcry_cipher_close(handle);
return 0;
}
/* g++ -std=c++11 xxx.cpp -L/usr/lib64 -lgcrypt -lgpg-error*/
any comment is welcome
i know it doesn't look that good , tried to be concised