前言
这两天主要是公司同事用到了RSA加密，事后也看了下，以为很简单，最终利用RSACryptoServiceProvider来实现RSA加密，然后大致了解到RSACryptoServiceProvider不支持跨平台，此类原先存在于.NET Framework中，本文我讲讲利用RSA.Create来实现各种加密模式统一封装。
RSA加密或解密
主要是在查找资料时看到了dudu老大写的有关RSA加密的文章（http://www.cnblogs.com/dudu/p/dotnet-core-rsa-openssl.html），刚好找到了我们项目中需要用到的openssl加密模式对应.NET Core中的Pkcs1，这里实现代码实在有点多，然后自己也遇到如评论中所说加密长度超出的情况，这个时候只能采取分段加密的方式。接下来我们来看看。首先看看如下代码：
var privateKey = "<RSAKeyValue><Modulus>0wE26IHp4U9OLtPhJ+fT8ej6aWORFP8pd++MjUuhkQQm/zhcImbxQbjxtSAftz+kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt+4UDMwKakgZqFoapDuwjKlTErFvKCyKCs+qN9OZvZwKWk=</Modulus><Exponent>AQAB</Exponent><P>8Ei6NIsZtgV3DQjuGHfGLS6o1O+IUXxzjqLxdMm77yhEPUxR9YPIxODJ2VVTddXSAHxViJJt30yJ7JhVz6cpQw==</P><Q>4M49NrmalgVQFMsea2RMB1qN8fAPfIw5G9q9hzsLcWSCmkeRRIQlvPYflVEKAYKiDVVzENETbnnduFXWBABx4w==</Q><DP>t+JQbemN0Zi5FQaif6MZzHYKynpNTl75aE0Wj5Pa+RlNr8N6bXNe8Bw/HM2Jw4HQ5oJASvYUk3DVlHS4JuP8VQ==</DP><DQ>lT62iv9brp9mU/epgVh71SH8PJPIZEJfo6tryjyb0zMMNcqvmZI1z6aCv0mm3+vPFBUXqCF1yhFj7n4l8FAvSw==</DQ><InverseQ>flrvgxHvf4l+fdymEVDgKjsfGqshOpppoNgZj9kpeWBto3o8z++Ki6eSLQT3nVnpx2QCZeTWkxTED4nhSLKscw==</InverseQ><D>cQTCg1Eqk7sltmFYxUYgOP/AOPjSufteG9acYwYymPkvZh6rAuY+rSRBmvGE62NUYskzuB/gM6iG2/2HrA5SixfNgCvZ+nsK+kX5pzQRsYdD71ViQW0hOanXwj45I2zHRgBiuTtCUP0fs5pISmQkaeJkDL5pO2l+wvlgl+wunj0=</D></RSAKeyValue>";
var publicKey = "<RSAKeyValue><Modulus>0wE26IHp4U9OLtPhJ+fT8ej6aWORFP8pd++MjUuhkQQm/zhcImbxQbjxtSAftz+kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt+4UDMwKakgZqFoapDuwjKlTErFvKCyKCs+qN9OZvZwKWk=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>"; using (var rsa = RSA.Create())
{
rsa.FromXmlString(publicKey);
}
经到github上查找解决方案，我们需要手动设置值，如下：
public static void FromXmlString(RSA rsa, string xmlString)
{
RSAParameters parameters = new RSAParameters(); XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml(xmlString); if (xmlDoc.DocumentElement.Name.Equals("RSAKeyValue"))
{
foreach (XmlNode node in xmlDoc.DocumentElement.ChildNodes)
{
switch (node.Name)
{
case "Modulus": parameters.Modulus = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "Exponent": parameters.Exponent = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "P": parameters.P = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "Q": parameters.Q = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "DP": parameters.DP = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "DQ": parameters.DQ = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "InverseQ": parameters.InverseQ = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "D": parameters.D = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
}
}
}
else
{
throw new Exception("Invalid XML RSA key.");
} rsa.ImportParameters(parameters);
}
其中经过很多尝试，要么是Base64格式不正确，要么是待解密的数据长度和Key Size无效，我第一次尝试是返回的加密字符串，然后进行解密，就是有问题，最后还是返回字节数组来进行加密和解密，直接看代码，这里解决了加密数据长度超出问题以及各种加密模式的统一，如下RSAHelper。
public static class RSAHelper
{
private const string privateKey = "<RSAKeyValue><Modulus>0wE26IHp4U9OLtPhJ+fT8ej6aWORFP8pd++MjUuhkQQm/zhcImbxQbjxtSAftz+kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt+4UDMwKakgZqFoapDuwjKlTErFvKCyKCs+qN9OZvZwKWk=</Modulus><Exponent>AQAB</Exponent><P>8Ei6NIsZtgV3DQjuGHfGLS6o1O+IUXxzjqLxdMm77yhEPUxR9YPIxODJ2VVTddXSAHxViJJt30yJ7JhVz6cpQw==</P><Q>4M49NrmalgVQFMsea2RMB1qN8fAPfIw5G9q9hzsLcWSCmkeRRIQlvPYflVEKAYKiDVVzENETbnnduFXWBABx4w==</Q><DP>t+JQbemN0Zi5FQaif6MZzHYKynpNTl75aE0Wj5Pa+RlNr8N6bXNe8Bw/HM2Jw4HQ5oJASvYUk3DVlHS4JuP8VQ==</DP><DQ>lT62iv9brp9mU/epgVh71SH8PJPIZEJfo6tryjyb0zMMNcqvmZI1z6aCv0mm3+vPFBUXqCF1yhFj7n4l8FAvSw==</DQ><InverseQ>flrvgxHvf4l+fdymEVDgKjsfGqshOpppoNgZj9kpeWBto3o8z++Ki6eSLQT3nVnpx2QCZeTWkxTED4nhSLKscw==</InverseQ><D>cQTCg1Eqk7sltmFYxUYgOP/AOPjSufteG9acYwYymPkvZh6rAuY+rSRBmvGE62NUYskzuB/gM6iG2/2HrA5SixfNgCvZ+nsK+kX5pzQRsYdD71ViQW0hOanXwj45I2zHRgBiuTtCUP0fs5pISmQkaeJkDL5pO2l+wvlgl+wunj0=</D></RSAKeyValue>";
private const string publicKey = "<RSAKeyValue><Modulus>0wE26IHp4U9OLtPhJ+fT8ej6aWORFP8pd++MjUuhkQQm/zhcImbxQbjxtSAftz+kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt+4UDMwKakgZqFoapDuwjKlTErFvKCyKCs+qN9OZvZwKWk=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>"; public static byte[] Encrypt(byte[] encryptBytes, RSAEncryptionPadding padding)
{
using (var rsa = RSA.Create())
{ FromXmlString(rsa, publicKey); var maxBlockSize = GetMaxBlockSize(rsa, padding); if (encryptBytes.Length <= maxBlockSize)
{
var @bytes = rsa.Encrypt(encryptBytes, padding);
return @bytes;
} using (var memoryStream = new MemoryStream(encryptBytes))
{
using (var readStream = new MemoryStream())
{
byte[] buffer = new byte[maxBlockSize]; int blockSize = memoryStream.Read(buffer, , maxBlockSize); while (blockSize > )
{
var blockByte = new byte[blockSize]; Array.Copy(buffer, , blockByte, , blockSize); var encrypts = rsa.Encrypt(blockByte, padding); readStream.Write(encrypts, , encrypts.Length); blockSize = memoryStream.Read(buffer, , maxBlockSize);
} return readStream.ToArray();
}
}
}
} public static byte[] Decrypt(byte[] decryptBytes, RSAEncryptionPadding padding)
{
using (var rsa = RSA.Create())
{
FromXmlString(rsa, privateKey); var maxBlockSize = rsa.KeySize / ; if (decryptBytes.Length <= maxBlockSize)
{
var @bytes = rsa.Decrypt(decryptBytes, padding);
return @bytes;
} using (var memoryStream = new MemoryStream(decryptBytes))
{
using (var readStream = new MemoryStream())
{
var buffer = new byte[maxBlockSize]; var blockSize = memoryStream.Read(buffer, , maxBlockSize); while (blockSize > )
{
var blockByte = new byte[blockSize]; Array.Copy(buffer, , blockByte, , blockSize); var decrypts = rsa.Decrypt(blockByte, padding); readStream.Write(decrypts, , decrypts.Length); blockSize = memoryStream.Read(buffer, , maxBlockSize);
} return readStream.ToArray();
}
}
}
} public static void FromXmlString(RSA rsa, string xmlString)
{
RSAParameters parameters = new RSAParameters(); XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml(xmlString); if (xmlDoc.DocumentElement.Name.Equals("RSAKeyValue"))
{
foreach (XmlNode node in xmlDoc.DocumentElement.ChildNodes)
{
switch (node.Name)
{
case "Modulus": parameters.Modulus = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "Exponent": parameters.Exponent = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "P": parameters.P = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "Q": parameters.Q = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "DP": parameters.DP = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "DQ": parameters.DQ = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "InverseQ": parameters.InverseQ = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
case "D": parameters.D = (string.IsNullOrEmpty(node.InnerText) ? null : Convert.FromBase64String(node.InnerText)); break;
}
}
}
else
{
throw new Exception("Invalid XML RSA key.");
} rsa.ImportParameters(parameters);
} static int GetMaxBlockSize(RSA rsa, RSAEncryptionPadding padding)
{
var offset = ;
if (padding.Mode == RSAEncryptionPaddingMode.Pkcs1)
{
offset = ;
}
else
{
if (padding.Equals(RSAEncryptionPadding.OaepSHA1))
{
offset = ;
} if (padding.Equals(RSAEncryptionPadding.OaepSHA256))
{
offset = ;
} if (padding.Equals(RSAEncryptionPadding.OaepSHA384))
{
offset = ;
} if (padding.Equals(RSAEncryptionPadding.OaepSHA512))
{
offset = ;
}
}
return rsa.KeySize / - offset;
}
}
我们开始进行如下测试，加密数据长度为6890，如下。
static void Main(string[] args)
{
var encryptString = "";
for (int i = ; i < ; i++)
{
encryptString += i;
} Console.WriteLine(encryptString.Length); var encryptBytes = Encoding.UTF8.GetBytes(encryptString); //加密后字节数组
var resultBytes = RSAHelper.Encrypt(encryptBytes, RSAEncryptionPadding.Pkcs1); //解密后字节数组
var decryptBytes = RSAHelper.Decrypt(resultBytes, RSAEncryptionPadding.Pkcs1); //解密结果
var result = Encoding.UTF8.GetString(decryptBytes); //比较加密字符串和解密结果是否相等
Console.WriteLine(encryptString == result);
Console.ReadKey();
}
总结
本文通过实现RSA加密和解密，同时也对加密数据超出采取分段加密的方式，测试在windows上通过，由于没有linux和mac环境未经测试，不知是否好使，一试见分晓。