Scoped app: Is there an API for base64 encoding / decoding raw byte arrays (not the Base64 encode/decode of string via GlideSystem)

[Sundeep7]

Wanted to know if we have any such APIs available for scoped apps? A sample use case is decoding encoded keys from a messaging provider- in this case, gs.base64Decode() is generating a different value compared to a server side JS invoker compared to how it would have been if we just fetched the raw bytes.

[Roy Verrips]

Hoping this helps as I had this problem and overcame it using an implementation of the fix script below:  It has a sample which was encoded externally and then decoded within ServiceNow using both gs.base64Encode and decoding it as Hex - The Hex decode may be why you may be getting a different result.   

var data = 'This is a test of payload data';
var secret = 'secret';
var EXTGeneratedSignature = '6d77f08aac96b28aa442960af0a0d5e0b9a80791aecb7b47829320bc724a408d';
// signature was generated by https://www.freeformatter.com/hmac-generator.html

var key = gs.base64Encode(secret);
var mac = new CertificateEncryption();
var SNgeneratedSignature = mac.generateMac(key, 'HmacSHA256', data);
var EXTdecode = hexToBase64(EXTGeneratedSignature);
if (SNgeneratedSignature == EXTdecode) {
    gs.info('The signature is valid');
} else {
    gs.info('the signature is not valid');
}

function hexToBase64(str) {
    function btoa(bin) {
        var tableStr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
        var table = tableStr.split('');
        for (var i = 0, j = 0, len = bin.length / 3, base64 = []; i < len; ++i) {
            var a = bin.charCodeAt(j++),
                b = bin.charCodeAt(j++),
                c = bin.charCodeAt(j++);
            if ((a | b | c) > 255) throw new Error('String contains an invalid character');
            base64[base64.length] =
                table[a >> 2] +
                table[((a << 4) & 63) | (b >> 4)] +
                (isNaN(b) ? '=' : table[((b << 2) & 63) | (c >> 6)]) +
                (isNaN(b + c) ? '=' : table[c & 63]);
        }
        return base64.join('');
    }
    return btoa(
        String.fromCharCode.apply(
            null,
            str
                .replace(/\r|\n/g, '')
                .replace(/([\da-fA-F]{2}) ?/g, '0x$1 ')
                .replace(/ +$/, '')
                .split(' ')
        )
    );
}