RSA密钥之C#格式与Java格式转换

前言

　　最近由于项目需求，服务端由c#编写，客户端由java编写。通信数据使用RSA非对称加密。但是java和c#生成的密钥格式是不一样的，所以需要转换格式才可以正常使用。网上搜到使用java进行格式转换的代码（如：http://blog.csdn.net/road2010/article/details/40071881 ），本文将给出一种c#的实现方法。

密钥格式

java密钥格式如下：

私钥：

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

公钥：

MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCkmUkhHT4b++zuaHJyzRl3kNtaiQwKwtfsiHfvf6WOW15GZObwgePRKXzMDbpC7+gCaqH04WTzTrNbdNeX3RGCFJ5CHNkFcUcGtMU3hT+jfA+FkF0VrOHzRtuySuZD+ObPvSpSbceYbOxve2jHM3oSFqR2juo/Ypzpo5VPJetimQIDAQAB

.NET密钥格式如下：

私钥：

<RSAKeyValue>
  <Modulus>pJlJIR0+G/vs7mhycs0Zd5DbWokMCsLX7Ih373+ljlteRmTm8IHj0Sl8zA26Qu/oAmqh9OFk806zW3TXl90RghSeQhzZBXFHBrTFN4U/o3wPhZBdFazh80bbskrmQ/jmz70qUm3HmGzsb3toxzN6Ehakdo7qP2Kc6aOVTyXrYpk=</Modulus>
  <Exponent>AQAB</Exponent>
  <P>1WKkFg6jlS2eZSVLiH1CK4b9uhr7qE1/L+tPqKQs+PzHX4eiZXnyAlQ+kgGmL7n1wR1RWNuiYnDZUetmTogaDQ==</P>
  <Q>xXhsuEnNJNQcQHEVTPZoulbMbTV1VZIDQ1zjG8fvu8sv6IBYcR5+EsC8n3/6RkW8/iCJDzxE++VHzhoSQSoDvQ==</Q>
  <DP>zr/rcn+umd0Aisnu/Ik48smxz39TdIfaAwkBPsoL1Re+6V2WyLG1/fG4SmmUpsuMRRdt+SWdmbnzpr7peo++hQ==</DP>
  <DQ>MWi2W04sBEEGaKFi4QTuo2FAeTrdBvIn2t0M/lCCjYyDijtC5drpVKvhBk+xQZAFf9iIMsWzxQtTciBX3PI0SQ==</DQ>
  <InverseQ>wGEfA3LWM4NHgRnXDqwwOUs3OtqWK0tsJPPcFMci+Bcgy96JpFTCr7bubXHMu14bdopCWUann2d3UuwEpvP+</InverseQ>
  <D>mK3TRtMwRJb33OGnn9OeFumYfy92qxi3X6Hq1o6qDBW2qkd4bImfv+ni6AinyOVuaadt2Y+lq4dKGcCVJzoZvPm1VKxD2y7xKa8/vEbPRiRTt0qnPq9T7UJkpDsiXf/zOMfWdjc3uA1bPnQ65RWHSJ7zAE+Gd7xnyCE5MEyijLE=</D>
</RSAKeyValue>

公钥：

<RSAKeyValue>
  <Modulus>pJlJIR0+G/vs7mhycs0Zd5DbWokMCsLX7Ih373+ljlteRmTm8IHj0Sl8zA26Qu/oAmqh9OFk806zW3TXl90RghSeQhzZBXFHBrTFN4U/o3wPhZBdFazh80bbskrmQ/jmz70qUm3HmGzsb3toxzN6Ehakdo7qP2Kc6aOVTyXrYpk=</Modulus>
  <Exponent>AQAB</Exponent>
</RSAKeyValue>

　　

转换实现代码（c#）

　　格式转换要用到一个开源加密库Bouncy Castle Crypto APIs，官网地址： http://www.bouncycastle.org/csharp/

　　具体实现代码如下：

using System;
using System.Xml;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Pkcs;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;

/// <summary>
/// RSA密钥格式转换
/// </summary>
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);
    }
}