ZPK Encryption ISO format 9594-1 Format 0 - encryption

Question

I need to integrate our IVR with ATM switch. In this case IVR needs to send pin block formed in ISO format 9594-1 Format 0 only (Zone pin key – Pin encryption). WE have Clear component - 1 ,2, & 3 & ZMK - Key check value. I need to know steps to generate PIN Block format 0 using ZPK encryption. Also as I am beginner need to know the role played here of clear component & ZMK .

Answer 1

Here is some javascript that will encrypt a pin into a Format-0 (PAN-free) pinblock. In this example it is creating a random DES ZPK (zone pin key), but you can use a fixed zone pin key if you wish. It is also using CryptoJS.
(I have an example in C# if you need it)
_createPinblockFromPin: function(pin) {
var pinBlockString = "1" + pin.length.toString() + pin;
while (pinBlockString.length < 16) {
var r = encoding.b2h((Math.random() * 0x100) & 255);
pinBlockString += r.toString(8).toUpperCase();
}
return pinBlockString;
}
_createZpk: function() {
var key = CryptoJS.enc.Hex.stringify(CryptoJS.lib.WordArray.random(16));
return key.toUpperCase();
}
_encryptPinBlock: function(clearPinBlockHex, zpkHex) {
var clearPinBlock = CryptoJS.enc.Hex.parse(clearPinBlockHex);
var key = CryptoJS.enc.Hex.parse(zpkHex);
key.words[4] = key.words[0];
key.words[5] = key.words[1];
var iv = CryptoJS.lib.WordArray.create(64 / 8);
var options = { iv: iv, mode: CryptoJS.mode.ECB, padding: CryptoJS.pad.NoPadding };
var encrypted = CryptoJS.TripleDES.encrypt(clearPinBlock, key, options);
var encryptedHex = encrypted.toString().toUpperCase();
return encryptedHex;
}
Usage is:
var clearPinBlock = this._createPinblockFromPin(pin);
var clearZpk = this._createZpk();
var ePinBlock = this._encryptPinBlock(clearPinBlock, clearZpk);
Here is a c# example that used BouncyCastle.net
// create zpk
var keyGenParams = new KeyGenerationParameters(new SecureRandom(), 128);
var keyGen = new DesEdeKeyGenerator();
keyGen.Init(keyGenParams);
var zpk = keyGen.GenerateKey();
System.Diagnostics.Debug.WriteLine($"zpk->{DataFormatter.ToHexString(zpk)}");
// create pinblock
var random = new Random();
var pinString = $"1{pin.Length}{pin}";
while (pinString.Length < 16) pinString += random.Next(0, 9).ToString();
var pinBlock = DataFormatter.HexStringToByteArray(pinString);
System.Diagnostics.Debug.WriteLine($"clearPinBlock->{DataFormatter.ToHexString(pinBlock)}");
// encrypt pinblock
var pinBlockZpk = new byte[8];
var keyParam = new DesEdeParameters(zpk);
var desEngine1 = new DesEdeEngine();
desEngine1.Init(true, keyParam);
desEngine1.ProcessBlock(pinBlock, 0, pinBlockZpk, 0);
System.Diagnostics.Debug.WriteLine($"pinBlockZpk-> {DataFormatter.ToHexString(pinBlockZpk)}");
Note that DataFormatter.ToHexString() is just a utility to convert a byte[] to a hex string for diagnostics.