Is there any way to represent 4 byte number as a 16 byte number?

Question

I have to encrypt some data using a 4 byte IV. However, the encryption algorithm that I am using (AES128)needs a 16 byte (128 bit) key. Say, my code is as follows:

#include<gcrypt.h>
void encrypt(){
    int IV = 6174;
    gcry_cipher_hd_t hd;        
    errStatus = gcry_cipher_open(&hd, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CBC, 0);
    errStatus = gcry_cipher_setkey(hd, keyBuffer, 16);
    gcry_cipher_setiv(hd, &IV, 16);
    gcry_cipher_encrypt(hd, output, 16, bytesToEncrypt, 16);
}

Say keyBuffer contains a 16 byte key and bytes,output` are my input and output respectively. How do I go about properly giving the IV?

Answer 1

Can you try this code just for avoiding buffer overflow? I haven't tested this myself, though

int IV[4] = { 6174 }; // { 6174, 0, 0, 0 }