/* Encrypts stdin to stdout using BLOWFISH */

#include <mcrypt.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

/* #include <mhash.h> */

typedef enum { ENCRYPT, DECRYPT } operation;

int main(int argc, char *argv[])
{
    MCRYPT td;
    int i;
    char *key;
    char password[20];
    char block_buffer;
    char *IV;
    int keysize=16;                               /* 128 bits */
    key=calloc(1, keysize);

    strcpy(password, "isa");

    operation op = ENCRYPT ;

    if ( argc == 2 && strcmp(argv[1], "-d") == 0 ) {
       op = DECRYPT;
    }

    /* Generate the key using the password */
    /*  mhash_keygen( KEYGEN_MCRYPT, MHASH_MD5, key, keysize, NULL, 0, password,
    strlen(password));
     */
    memmove( key, password, strlen(password));
    td = mcrypt_module_open("blowfish", NULL, "cfb", NULL);
    if (td==MCRYPT_FAILED)
    {
        return 1;
    }

    IV = malloc(mcrypt_enc_get_iv_size(td));

    // Put random data in IV. Does not have to be secrete, can even be public.
    for (i=0; i< mcrypt_enc_get_iv_size(td); i++)
    {
        IV[i] = rand();
    }

    i=mcrypt_generic_init( td, key, keysize, IV);

    if (i<0)
    {
        mcrypt_perror(i);
        return 1;
    }

    /* Encryption in CFB is performed in bytes */
    while ( fread (&block_buffer, 1, 1, stdin) == 1 )
    {
        if ( op == ENCRYPT ) {
           mcrypt_generic (td, &block_buffer, 1);
        } else {
           mdecrypt_generic (td, &block_buffer, 1);
        }

        fwrite ( &block_buffer, 1, 1, stdout);
    }
    /* Deinit the encryption thread, and unload the module */
    mcrypt_generic_end(td);
    return 0;
}