Just some easier code for Duplicati Login with known NONCE and Salted Password.

generate_nonced_password.js

const base64Decode = str => Uint8Array.from(atob(str), c => c.charCodeAt(0));
const base64Encode = bytes => btoa(String.fromCharCode(...new Uint8Array(bytes)));

const generatePassword = async (nounce, saltedPassword) => {
    const bytesNounce = base64Decode(nounce);
    const bytesSaltedPassword = base64Decode(saltedPassword);
    const concatenatedBytes = new Uint8Array([...bytesNounce, ...bytesSaltedPassword]);
    const hash = await crypto.subtle.digest('SHA-256', concatenatedBytes);
    return base64Encode(hash);
};

const urlEncode = str => encodeURIComponent(str).replace(/%20/g, '+');

const nounce = 'NONCE';
const saltedPassword = 'SALTED_PASSWORD';

generatePassword(nounce, saltedPassword).then(noncedPassword => {
    console.log(noncedPassword, urlEncode(noncedPassword));
});

generate_nonced_password.py

import hashlib
import base64
from urllib.parse import unquote, quote_plus

def generate_password(nounce: str, salted_password: str):
    bytes_nounce, bytes_salted_password  = base64.b64decode(unquote(nounce)), base64.b64decode(salted_password)
    hex_nounce, hex_salted_password = bytes_nounce.hex(), bytes_salted_password.hex()
    hex_concatenated = hex_nounce + hex_salted_password
    concatenated_bytes = bytes.fromhex(hex_concatenated)
    sha256_hash = hashlib.sha256(concatenated_bytes).digest()
    return base64.b64encode(sha256_hash).decode('utf-8')

nonced_password = generate_password('NONCE', 'SALTED_PASSWORD')
url_encoded_nonced_password = quote_plus(nonced_password)

print(nonced_password, url_encoded_nonced_password)