aes.c

#include <openssl/aes.h>
#include <stdio.h>

//AES ENCRYPTION KEY (CHANGE THIS)
static const unsigned char key[] = {
    0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
    0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
    0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
};

int main(int argc, char *argv[]) {

    AES_KEY enc_key, dec_key;
    unsigned char enc_out[1024];
    unsigned char dec_out[1024];

    if (strcmp(argv[2], "1") == 0)
    {
        AES_set_encrypt_key(key, 256, &enc_key);
        int len = strlen(argv[1]); //or get cipher text length by any mean.
        int i;
        for(i=0; i<=len; i+=16)
            AES_encrypt(argv[1]+i, enc_out+i, &enc_key);
        //AES_encrypt(argv[1], enc_out, &enc_key);
        puts(enc_out);
        return 0;
    } else {
        AES_set_decrypt_key(key, 256,&dec_key);
        int len = strlen(argv[1]); //or get cipher text length by any mean.
        int i;
        for(i=0; i<=len; i+=16)
            AES_decrypt(argv[1]+i, dec_out+i, &dec_key);
        //AES_decrypt(argv[1], dec_out, &dec_key);
        puts(dec_out);
        return 0;
    }
}