一、.net → java RSA轉換

 /// <summary>
    /// RSA金鑰格式轉換
    /// </summary>
    public static class RSAConverter
    {
        /// <summary>    
        /// RSA私鑰格式轉換，java->.net    
        /// </summary>    
        /// <param name="privateKey">java生成的RSA私鑰</param>    
        /// <returns></returns>
 
   
        public static string RSAPrivateKeyJava2DotNet(this string privateKey)
        {
            RsaPrivateCrtKeyParameters privateKeyParam = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(Convert.FromBase64String(privateKey));
            return string.Format("<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent><P>{2}</P><Q>{3}</Q><DP>{4}</DP><DQ>{5}</DQ><InverseQ>{6}</InverseQ><D>{7}</D></RSAKeyValue>
 
",
            Convert.ToBase64String(privateKeyParam.Modulus.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.PublicExponent.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.P.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.Q.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.DP.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.DQ.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.QInv.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.Exponent.ToByteArrayUnsigned()));
        }

        
 
/// <summary>    
        /// RSA私鑰格式轉換，.net->java    
        /// </summary>    
        /// <param name="privateKey">.net生成的私鑰</param>    
        /// <returns></returns>   
        public static string RSAPrivateKeyDotNet2Java(this string privateKey)
        {
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(privateKey);
            BigInteger m = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Modulus")[0].InnerText));
            BigInteger exp = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Exponent")[0].InnerText));
            BigInteger d = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("D")[0].InnerText));
            BigInteger p = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("P")[0].InnerText));
            BigInteger q = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Q")[0].InnerText));
            BigInteger dp = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("DP")[0].InnerText));
            BigInteger dq = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("DQ")[0].InnerText));
            BigInteger qinv = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("InverseQ")[0].InnerText));
            RsaPrivateCrtKeyParameters privateKeyParam = new RsaPrivateCrtKeyParameters(m, exp, d, p, q, dp, dq, qinv);
            PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(privateKeyParam);
            byte[] serializedPrivateBytes = privateKeyInfo.ToAsn1Object().GetEncoded();
            return Convert.ToBase64String(serializedPrivateBytes);
        }

        /// <summary>    
        /// RSA公鑰格式轉換，java->.net    
        /// </summary>    
        /// <param name="publicKey">java生成的公鑰</param>    
        /// <returns></returns>    
        public static string RSAPublicKeyJava2DotNet(this string publicKey)
        {
            RsaKeyParameters publicKeyParam = (RsaKeyParameters)PublicKeyFactory.CreateKey(Convert.FromBase64String(publicKey));
            return string.Format("<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent></RSAKeyValue>",
                Convert.ToBase64String(publicKeyParam.Modulus.ToByteArrayUnsigned()),
                Convert.ToBase64String(publicKeyParam.Exponent.ToByteArrayUnsigned()));
        }

        /// <summary>    
        /// RSA公鑰格式轉換，.net->java    
        /// </summary>    
        /// <param name="publicKey">.net生成的公鑰</param>    
        /// <returns></returns>   
        public static string RSAPublicKeyDotNet2Java(this string publicKey)
        {
            XmlDocument doc = new XmlDocument(); doc.LoadXml(publicKey);
            BigInteger m = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Modulus")[0].InnerText));
            BigInteger p = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Exponent")[0].InnerText));
            RsaKeyParameters pub = new RsaKeyParameters(false, m, p);
            SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(pub);
            byte[] serializedPublicBytes = publicKeyInfo.ToAsn1Object().GetDerEncoded();
            return Convert.ToBase64String(serializedPublicBytes);
        }
    }

二、示例

       /// <summary>
        /// .net RSA私鑰解密
        /// </summary>
        private static void test()
        {
            string privateKey = @"MIIBVQIBADANBgkqhkiG9w0BAQEFAASCAT8wggE7AgEAAkEA2fy4b8rHvwhvEGY3

hGSoIVHOPNN0DzEm01kZ0hpoxO6kZzmuecZRyTJTai42ujupqVSD4aWPuStuAul7

whzjtwIDAQABAkArY89+iRmLX+1jkUUZuENzJmpr1xcx8vGsff7SwGj8Uboic0Rc

ydQr74MX+j2k71PrfCaScX9P7Bo2WQixeTDpAiEA7QoIXFkuUj2dcj5XuaBUUww8

c+USpjDlSt+ocOaeAPUCIQDrbIz4Z1D1cXzCuWbLTQaVTC5p2seCpzGgjFt+ycv2

ewIhAK2twzB++4ywrrMtcLOHASIUfhrgxkhU3Tx+IfoPT8gdAiEAxZGwcFqMF57o

+6WJ/b0jdDGdldozqpLTVA/WTP3e/HcCIDmNqE4Lyx2tgIrQDIgi9R7Fe30vgCwR

0ju33PubEg5f";


            string k = "<?xml version='1.0'>" + privateKey.RSAPrivateKeyJava2DotNet();

            String enStr = "HItL1liIdBn3orZmCUSJoyQ8038aXfjYs7xCNoepYAbsG+a4u74Tiy+ppUVD4Y8fXs8hdUK05SEfNC+/Pk41Fg==";

            //解密
            string y = Decrypt(enStr, k);

        }