如题。使用SAML单点登录对IDP返回的Response断言使用微软提供的Microsoft.IdentityModel.Tokens对断言（Assertion）进行校验。

首先需要安装Muget包，Microsoft.IdentityModel.Tokens和Microsoft.IdentityModel.Tokens.Saml。

简易示例代码如下：

private X509SecurityKey GetSigningCertificate()
{//SAMLResponse ds:X509Data节点证书信息string samlCertificate = @"MIIC8DCCAdigAwIBAgIQY97pbBoha5tHlCRNbt64bjANBgkqhkiG9w0BAQsFADA0MTIwMAYDVQQDEylNaWNyb3NEiy9NIRqat894uFw2sxSlEe2zOSI1jBQVkI0qu/fAFEG/cK9/SMQ40f8/aLalWU6i2x5k3pslmuf1DN76mCIImBNxGBqtWKkRWZTuxbJ0zay70owDfS4JKsz";byte[] certBytes = Convert.FromBase64String(samlCertificate);X509Certificate2 certificate = new X509Certificate2(certBytes);//如果将证书安装在服务器，也可以调用证书，注意替换证书指纹// 加载用于验证签名的证书//var store = new X509Store(StoreName.My, StoreLocation.LocalMachine);//store.Open(OpenFlags.ReadOnly);//var certs = store.Certificates.Find(X509FindType.FindByThumbprint, "证书指纹", false);//store.Close();//if (certs.Count == 0)//    throw new Exception("Signing certificate not found.");//var key = new X509SecurityKey(certs[0]);var key = new X509SecurityKey(certificate);return key;
}public bool ValidateSamlAssertionSignature()
{string samlAssertion = Request.Form["SAMLResponse"].ToString();byte[] samlResponseBytes = Convert.FromBase64String(samlAssertion);// 将字节数组转换为 XML 文档XmlDocument samlResponseDoc = new XmlDocument();samlResponseDoc.Load(new MemoryStream(samlResponseBytes));// 从 SAML Response 中提取 Assertion 节点XmlNode assertionNode = samlResponseDoc.SelectSingleNode("//*[local-name()='Assertion' and namespace-uri()='urn:oasis:names:tc:SAML:2.0:assertion']");var tokenHandler = new Saml2SecurityTokenHandler();var validationParameters = new TokenValidationParameters{ValidateIssuer = true, // 根据需要设置ValidIssuer = "IDP提供的标识符",//Issuer节点ValidateAudience = false, // 根据需要设置ValidAudience= "你的EntityID",// 从证书存储中获取用于验证签名的证书IssuerSigningKey = GetSigningCertificate(),ValidateLifetime = true // 验证令牌是否在有效期内//以及其他校验点};try{//返回登录者信息，进行下一步处理ClaimsPrincipal securityToken = tokenHandler.ValidateToken(assertionNode.OuterXml, validationParameters, out var rawToken);var samlToken = rawToken as Saml2SecurityToken;// 验证成功，samlToken 包含断言信息，正常应该跳转到登录成功页面return true;}catch (SecurityTokenValidationException){// 验证失败return false;}
}

也可以使用开源的saml库。比如AspNetSaml，ITfoxtec.Identity.Saml2以及Sustainsys.Saml2等