问解密SAML响应

EN

namespace SAMLDecrypter
{
    class Program
    {
        static void Main(string[] args)
        {
            var certPath = "cartPath";
            var samlPath = "samlresponse.xml";
            var saml = XElement.Parse(File.ReadAllText(samlPath));
            var cert = X509Certificate2.CreateFromPemFile(certPath);
            var cipherKeys = GetCipherValues(saml);
            var privateKey = cert.GetRSAPrivateKey();
            var aeskey = privateKey.Decrypt(Convert.FromBase64String(cipherKeys[0]), RSAEncryptionPadding.OaepSHA1);
            var assertions = AesDecrypt(Convert.FromBase64String(cipherKeys[1]), aeskey);
            assertions = XElement.Parse(assertions.Substring(assertions.IndexOf("<"))).ToString();

            Console.WriteLine(assertions);
        }

        static string[] GetCipherValues(XElement saml)
        {
            var alg = XName.Get("Algorithm");
            var encryptedData = XPathSelectElements(saml, "./saml2:EncryptedAssertion/xenc:EncryptedData").First();
            var encryptionMethod = XPathSelectElements(encryptedData, "./xenc:EncryptionMethod").First().Attribute(alg).Value;
            var keyInfo = XPathSelectElements(encryptedData, "./ds:KeyInfo").First();
            var encryptionMethodKey = XPathSelectElements(keyInfo, "./xenc:EncryptedKey/xenc:EncryptionMethod").First().Attribute(alg).Value;
            var cipherValueKey = XPathSelectElements(keyInfo, "./xenc:EncryptedKey/xenc:CipherData/xenc:CipherValue").First().Value;
            var cipherValue = XPathSelectElements(encryptedData, "./xenc:CipherData/xenc:CipherValue").First().Value;
            return new[] { cipherValueKey, cipherValue };
        }

        private static Dictionary<string, string> GetDefaultDict()
        {
            return new Dictionary<string, string>
            {
                { "saml2", "urn:oasis:names:tc:SAML:2.0:assertion" },
                { "saml2p", "urn:oasis:names:tc:SAML:2.0:protocol" },
                { "xenc", "http://www.w3.org/2001/04/xmlenc#" },
                { "ds", "http://www.w3.org/2000/09/xmldsig#" }
            };
        }

        private static IEnumerable<XElement> XPathSelectElements(XNode element, string query)
        {
            return XPathSelectElements(element, query, GetDefaultDict());
        }

        private static IEnumerable<XElement> XPathSelectElements(XNode element, string query, Dictionary<string,string> namespaces)
        {
            var namespaceManager = new XmlNamespaceManager(new NameTable());
            namespaces.ToList().ForEach(entry => namespaceManager.AddNamespace(entry.Key, entry.Value));
            return element.XPathSelectElements(query, namespaceManager);
        }

        static string AesDecrypt(byte[] cipherText, byte[] aesKey)
        {
            // Check arguments.
            if (cipherText == null || cipherText.Length <= 0)
                throw new ArgumentNullException("cipherText");
            if (aesKey == null || aesKey.Length < 16)
                throw new ArgumentNullException("Key");

            var aesIV = aesKey.Take(16).ToArray();
            using (var ms = new MemoryStream())
            {
                using (var aes = new AesManaged()) {
                    aes.Key = aesKey;
                    aes.IV = aesIV;
                    aes.Padding = PaddingMode.ISO10126;
                    CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write);
                    cs.Write(cipherText, 0, cipherText.Length);
                    cs.Close();
                    var result = Encoding.UTF8.GetString(ms.ToArray());
                    return result;
                }
            }
        }

    }
}