facebook webhook签名计算(C#)

using System;
using System.Security.Cryptography;
using System.Text;

public class FacebookWebhookSignature
{
    public static bool VerifySignature(string requestBody, string signatureHeader, string appSecret)
    {
        var signature = signatureHeader.Replace("sha1=", "");
        var secretBytes = Encoding.UTF8.GetBytes(appSecret);
        var requestBodyBytes = Encoding.UTF8.GetBytes(requestBody);

        using (var hmac = new HMACSHA1(secretBytes))
        {
            var hashBytes = hmac.ComputeHash(requestBodyBytes);
            var hashString = BitConverter.ToString(hashBytes).Replace("-", "").ToLower();

            return hashString.Equals(signature);
        }
    }
}