using System.Security.Cryptography;
public static void Main()
Encoding ascii = Encoding.ASCII;
String passphrase = "blahs";
String input_for_hash = "&secret=1617666146730x499209949986422800&epoch=1618594736&backendURI=https://graph.microsoft.com/v1.0/drives/b!zqQECMNv4UmKUnm4PzVglT2NNyP-10pOoOrAZ1IpYin3fhu94xNLTa4_qYzNVy0R/items/01HIWRJHMZGAJCRGA6QVG2N4E4THZ3PRCB/content";
String hash_received_in_URL = "WYoJBphUQc+jdkwv6amXpJWxBmqMX3I22dGbuK8vcus=";
HMACSHA256 hmac = new HMACSHA256(ascii.GetBytes(passphrase));
String calculated_hash = Convert.ToBase64String(hmac.ComputeHash(ascii.GetBytes(input_for_hash)));
if (hash_received_in_URL == calculated_hash) {
Console.WriteLine("Matches");
Console.WriteLine("Does not match");