Question

I’m writing an encryption to my application and website, but I don’t know how to correctly encrypt the string in php. Decryption is already done by this code:

function decrypt_blowfish($data,$key){
$iv=pack("H*" , substr($data,0,16));
$key=pack("H*" , $key);
$x =pack("H*" , substr($data,16)); 
$res = mcrypt_decrypt(MCRYPT_BLOWFISH, $key, $x , MCRYPT_MODE_CBC, $iv);
return $res;
}

I tried with simple:

function encrypt_blowfish($data,$key){
    $iv_size = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $crypttext = mcrypt_encrypt(MCRYPT_BLOWFISH, $key, $data, MCRYPT_MODE_CBC, $iv);
    return $crypttext;
}

But it returns strang ASCI chars instead of correct blowfish code. Could somebody explain me why, and what am I doing wrong?
Thanks in advance

C.H.

Answer 1

function decrypt_blowfish($data,$key){
    $iv=pack("H*" , substr($data,0,16));
    $x =pack("H*" , substr($data,16)); 
    $res = mcrypt_decrypt(MCRYPT_BLOWFISH, $key, $x , MCRYPT_MODE_CBC, $iv);
    return $res;
}

function encrypt_blowfish($data,$key){
    $iv_size = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $crypttext = mcrypt_encrypt(MCRYPT_BLOWFISH, $key, $data, MCRYPT_MODE_CBC, $iv);
    return bin2hex($iv . $crypttext);
}

$string = encrypt_blowfish('hello world', 'abc123');
echo 'ENCRYPTED: ' . $string . "\n";
echo 'DECRYPTED: ' . decrypt_blowfish($string, 'abc123');

Try that. In the decryption function you are converting from hex to binary, so it is expecting a hex value to be passed. Your encryption function is outputting binary, so you need to convert it to hex with the above change.