public static IDictionary<string, object> DecodeJWT(string jwttoken,string key){//从/.well-known/openid-configuration路径获取jwks_urivar webClient = new WebClient();var endpoint = "http://localhost:5000/.well-known/openid-configuration";var json = webClient.DownloadString(endpoint);JObject metadata = JsonConvert.DeserializeObject<JObject>(json);var jwksUri = metadata["jwks_uri"].ToString();//从jwks_uri获取keysjson = webClient.DownloadString(jwksUri);var keys = JsonConvert.DeserializeObject<CustomJWKs>(json);//从jwt获取头部kid,并从keys中找到匹配kid的keystring[] tokenParts = jwttoken.Split('.');byte[] bytes = FromBase64Url(tokenParts[0]);string head= Encoding.UTF8.GetString(bytes);string kid = JsonConvert.DeserializeObject<JObject>(head)["kid"].ToString();var defaultkey=keys.keys.Where(t => t.kid == kid).FirstOrDefault();if(defaultkey==null){throw new Exception("未找到匹配的kid");}//jwt解密return RS256Decode(jwttoken, key, defaultkey.e, defaultkey.n);}public static IDictionary<string, object> RS256Decode(string token, string secret, string exponent,string modulus){try{IJsonSerializer serializer = new JsonNetSerializer();IDateTimeProvider provider = new UtcDateTimeProvider();IJwtValidator validator = new JwtValidator(serializer, provider);IBase64UrlEncoder urlEncoder = new JwtBase64UrlEncoder();RSAlgorithmFactory rS256Algorithm = new RSAlgorithmFactory(() =>{RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();rsa.ImportParameters(new RSAParameters(){Modulus = FromBase64Url(modulus),Exponent = FromBase64Url(exponent)});byte[] rsaBytes = rsa.ExportCspBlob(true);X509Certificate2 cert = new X509Certificate2(rsaBytes);return cert;});IJwtDecoder decoder = new JwtDecoder(serializer, validator, urlEncoder, rS256Algorithm);var json = decoder.DecodeToObject(token, secret, verify: false);return json;}catch (TokenExpiredException){throw new Exception("token已过期");//Console.WriteLine("Token has expired");//return null;
            }catch (SignatureVerificationException){throw new Exception("token验证失败");//Console.WriteLine("Token has invalid signature");//return null;
            }}public static byte[] FromBase64Url(string base64Url){string padded = base64Url.Length % 4 == 0? base64Url : base64Url + "====".Substring(base64Url.Length % 4);string base64 = padded.Replace("_", "/").Replace("-", "+");return Convert.FromBase64String(base64);}