Converting LDAP objectGUID to Base64 and vice versa

Mike225 · ‎04-30-2025

I could never find ES5 compatible code that reliably converts the AD Object GUID that comes in from LDAP to and from Base64. Hope this helps someone out there!

One issue with community questions is service now does not let your body have the letters K L M without spaces
"

The message body contains K-L-M, which is not permitted in this community. Please remove this content before sending your post.

"

So to make this compatible with this post the variable base64Chars looks funky, but will work.

Here is a script include that will do that for you:

var ADUtils = Class.create();

ADUtils.prototype = {

initialize: function() {},

base64ToGuid: function(base64String) {

// Base64 character set

var base64Chars = 'ABCDEFGHIJ' + 'K' + 'LMNOPQRSTUVWXYZabcdefghij' + 'k' + 'lmnopqrstuvwxyz0123456789+/';

// Function to decode a Base64 character

function decodeBase64Char(c) {

var index = base64Chars.indexOf(c);

if (index === -1) {

return -1; // Invalid character

}

return index;

}

try {

// Ensure the base64 string is valid

if (!base64String || base64String.length % 4 !== 0) {

gs.error("Invalid Base64 string: Length is not a multiple of 4. Input: " + base64String);

return null; // Invalid Base64 string

}

// Remove padding characters

var padding = 0;

if (base64String.charAt(base64String.length - 1) === '=') {

padding++;

if (base64String.charAt(base64String.length - 2) === '=') {

padding++;

}

base64String = base64String.substring(0, base64String.length - padding);

}

// Calculate the number of bytes

var byteCount = (base64String.length * 3) / 4 - padding;

var byteArray = [];

var b1, b2, b3;

var i = 0;

var j = 0;

// Decode the Base64 string

for (i = 0; i < base64String.length; i += 4) {

var c1 = decodeBase64Char(base64String.charAt(i));

var c2 = decodeBase64Char(base64String.charAt(i + 1));

var c3 = decodeBase64Char(base64String.charAt(i + 2));

var c4 = decodeBase64Char(base64String.charAt(i + 3));

if (c1 === -1 || c2 === -1) {

gs.error("Invalid Base64 character at position " + i + ". c1:" + c1 + " c2:" + c2 + " c3:" + c3 + " c4:" + c4);

return null; // Invalid Base64 character

}

b1 = (c1 << 2) | (c2 >> 4);

byteArray[j++] = b1;

if (c3 !== -1 && j < byteCount) { //check if we are about to write too many bytes

b2 = ((c2 & 15) << 4) | (c3 >> 2);

byteArray[j++] = b2;

}

if (c4 !== -1 && j < byteCount) { //check if we are about to write too many bytes

b3 = ((c3 & 3) << 6) | c4;

byteArray[j++] = b3;

}

// Ensure the byte array is 16 bytes long

if (byteArray.length !== 16) {

gs.error("Byte array is not 16 bytes long. Found: " + byteArray.length + ". Expected 16. Array contents: " + byteArray);

return null;

}

// Reconstruct the GUID parts with the specific byte order reversal

function toHex(value) {

var hex = value.toString(16).toUpperCase();

return hex.length === 1 ? '0' + hex : hex;

}

var part1 = (

toHex(byteArray[3]) +

toHex(byteArray[2]) +

toHex(byteArray[1]) +

toHex(byteArray[0])

);

var part2 = (

toHex(byteArray[5]) +

toHex(byteArray[4])

);

var part3 = (

toHex(byteArray[7]) +

toHex(byteArray[6])

);

var part4 = (

toHex(byteArray[8]) +

toHex(byteArray[9])

);

var part5Arr = [];

for (var k = 10; k < 16; k++) {

part5Arr.push(toHex(byteArray[k]));

}

var part5 = part5Arr.join('');

// Format the GUID string

var guid = (part1 + '-' + part2 + '-' + part3 + '-' + part4 + '-' + part5).toLowerCase();

return guid;

} catch (error) {

gs.error("Error during Base64 to GUID conversion:" + JSON.stringify(error, null, 4));

return null;

}

},

guidToBase64: function(guidToConvert) {

// Remove hyphens and convert to lowercase

var hexString = guid.replace(/-/g, '').toLowerCase();

// Ensure the hex string has 32 characters

if (hexString.length !== 32) {

gs.error("Invalid GUID format. Input:" + guid);

return null;

}

// Convert hex string to byte array, applying specific byte order

var byteArray = [];

// Part 1 (bytes 0-3): Reverse byte order

byteArray[0] = parseInt(hexString.substring(6, 8), 16);

byteArray[1] = parseInt(hexString.substring(4, 6), 16);

byteArray[2] = parseInt(hexString.substring(2, 4), 16);

byteArray[3] = parseInt(hexString.substring(0, 2), 16);

// Part 2 (bytes 4-5): Reverse byte order

byteArray[4] = parseInt(hexString.substring(10, 12), 16);

byteArray[5] = parseInt(hexString.substring(8, 10), 16);

// Part 3 (bytes 6-7): Reverse byte order

byteArray[6] = parseInt(hexString.substring(14, 16), 16);

byteArray[7] = parseInt(hexString.substring(12, 14), 16);

// Part 4 (bytes 8-9): No reversal

byteArray[8] = parseInt(hexString.substring(16, 18), 16);

byteArray[9] = parseInt(hexString.substring(18, 20), 16);

// Part 5 (bytes 10-15): No reversal

for (var i = 0; i < 6; i++) {

byteArray[10 + i] = parseInt(hexString.substring(20 + (i * 2), 22 + (i * 2)), 16);

}

// Convert byte array to Base64 string (without btoa)

var base64Chars = 'ABCDEFGHIJ' + 'K' + 'LMNOPQRSTUVWXYZabcdefghij' + 'k' + 'lmnopqrstuvwxyz0123456789+/';

var base64String = '';

var padding = '';

for (var i = 0; i < byteArray.length; i += 3) {

var a = byteArray[i];

var b = byteArray[i + 1];

var c = byteArray[i + 2];

var c1 = (a >> 2) & 0x3f;

var c2 = ((a & 0x3) << 4) | ((b & 0xf0) >> 4);

var c3 = ((b & 0x0f) << 2) | ((c & 0xc0) >> 6);

var c4 = c & 0x3f;

base64String += base64Chars.charAt(c1);

base64String += base64Chars.charAt(c2);

if (isNaN(b)) {

padding = '=';

base64String += padding;

break;

}

base64String += base64Chars.charAt(c3);

if (isNaN(c)) {

padding = '=';

base64String += padding;

break;

}

base64String += base64Chars.charAt(c4);

}

while (base64String.length % 4) {

base64String += '=';

padding++;

}

return base64String;

},

type: 'ADUtils'

};

jawnmower · ‎08-04-2025

I'm implementing this from an OnComplete transform script that calls

ADUtils.base64ToGuid();

So how should I get base64String passed into the script include? Where is base64String declared, AD?