由于项目的原因，原来的项目使用.net 进行开发，现在需要转成java， 所以原来的加解密就成了一个棘手的问题。由于数据使用RSA签名加密，又因为.net 和 Java 加解密算法上的差异，并不能使用同一个私钥来对原始数据进行解密。所以考虑的方向就是签名密钥之间互相转换。

有幸的是，网络上也有很多遇到此问题的朋友，网上也有类似的很多解决方法。但是寻找最终的解决方案还是花了很长时间。再加上自己对程序上的修改，得出了比较适合自己转换的一个解决方案吧。

转换需要使用BouncyCastle.Crypto.dll

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Xml;

using System.Security.Cryptography;

using Org.BouncyCastle.Crypto.Parameters;

using Org.BouncyCastle.Asn1.Pkcs;

using Org.BouncyCastle.Pkcs;

using Org.BouncyCastle.Math;

using Org.BouncyCastle.Asn1.X509;

using Org.BouncyCastle.X509;

using Org.BouncyCastle.Security;

namespace RSADemo

{

    public class RSAKeyConvert

    {

        /// <summary>

        /// RSA私钥格式转换，java->.net

        /// </summary>

        /// <param name="privateKey">java生成的RSA私钥</param>

        /// <returns></returns>

        public static string RSAPrivateKeyJava2DotNet(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私钥格式转换，.net->java

        /// </summary>

        /// <param name="privateKey">.net生成的私钥</param>

        /// <returns></returns>

        public static string RSAPrivateKeyDotNet2Java(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公钥格式转换，java->.net

        /// </summary>

        /// <param name="publicKey">java生成的公钥</param>

        /// <returns></returns>

        public static string RSAPublicKeyJava2DotNet(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公钥格式转换，.net->java

        /// </summary>

        /// <param name="publicKey">.net生成的公钥</param>

        /// <returns></returns>

        public static string RSAPublicKeyDotNet2Java(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);

        }

    }

}

写于2016-07-19