.NET使用OpenSSL生成的pem密钥文件

NET要使用OpenSSL生成的pem密钥文件，网上资料很少（http://www.faqs.org/rfcs/rfc1421.html，RFC1421文件又老长老长），仅有的资料还是有错误的，所以今天干了件体力活，把PEM密钥文件610个字节一个个看过来，终于搞清了它的格式。

using System;
using System.Text;
using System.Security.Cryptography;
using System.Web;
using System.IO;

namespace Thinhunan.Cnblogs.Com.RSAUtility
{
public class PemConverter
{
/// <summary>
/// 将pem格式公钥转换为RSAParameters
/// </summary>
/// <param name="pemFileConent">pem公钥内容</param>
/// <returns>转换得到的RSAParamenters</returns>
public static RSAParameters ConvertFromPemPublicKey(string pemFileConent)
{
if (string.IsNullOrEmpty(pemFileConent))
{
throw new ArgumentNullException("pemFileConent", "This arg cann't be empty.");
}
pemFileConent = pemFileConent.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("\n", "").Replace("\r", "");
byte[] keyData = Convert.FromBase64String(pemFileConent);
if (keyData.Length < 162)
{
throw new ArgumentException("pem file content is incorrect.");
}
byte[] pemModulus = new byte[128];
byte[] pemPublicExponent = new byte[3];
Array.Copy(keyData, 29, pemModulus, 0, 128);
Array.Copy(keyData, 159, pemPublicExponent, 0, 3);
RSAParameters para = new RSAParameters();
para.Modulus = pemModulus;
para.Exponent = pemPublicExponent;
return para;
}

/// <summary>
/// 将pem格式私钥转换为RSAParameters
/// </summary>
/// <param name="pemFileConent">pem私钥内容</param>
/// <returns>转换得到的RSAParamenters</returns>
public static RSAParameters ConvertFromPemPrivateKey(string pemFileConent)
{
if (string.IsNullOrEmpty(pemFileConent))
{
throw new ArgumentNullException("pemFileConent", "This arg cann't be empty.");
}
pemFileConent = pemFileConent.Replace("-----BEGIN RSA PRIVATE KEY-----", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("\n", "").Replace("\r","");
byte[] keyData = Convert.FromBase64String(pemFileConent);
if (keyData.Length < 609)
{
throw new ArgumentException("pem file content is incorrect.");
}

int index = 11;
byte[] pemModulus = new byte[128];
Array.Copy(keyData, index, pemModulus, 0, 128);

index += 128;
index += 2;//141
byte[] pemPublicExponent = new byte[3];
Array.Copy(keyData, index, pemPublicExponent, 0, 3);

index += 3;
index += 4;//148
byte[] pemPrivateExponent = new byte[128];
Array.Copy(keyData, index , pemPrivateExponent, 0, 128);

index += 128;
index += ((int)keyData[index+1] == 64?2: 3);//279
byte[] pemPrime1 = new byte[64];
Array.Copy(keyData, index, pemPrime1, 0, 64);

index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);//346
byte[] pemPrime2 = new byte[64];
Array.Copy(keyData, index , pemPrime2, 0, 64);

index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);//412/413
byte[] pemExponent1 = new byte[64];
Array.Copy(keyData,index, pemExponent1, 0, 64);

index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);//479/480
byte[] pemExponent2 = new byte[64];
Array.Copy(keyData, index, pemExponent2, 0, 64);

index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);//545/546
byte[] pemCoefficient = new byte[64];
Array.Copy(keyData, index, pemCoefficient, 0, 64);

RSAParameters para = new RSAParameters();
para.Modulus = pemModulus;
para.Exponent = pemPublicExponent;
para.D = pemPrivateExponent;
para.P = pemPrime1;
para.Q = pemPrime2;
para.DP = pemExponent1;
para.DQ = pemExponent2;
para.InverseQ = pemCoefficient;
return para;
}

}
}

测试pem导成RSAParameters成功，使用通过：
using System;
using System.Security.Cryptography;
using System.Text;
using System.IO;
using System.Web;

namespace Thinhunan.Cnblogs.Com.RSAUtility
{
class Program
{
#region keys

const string PUBLICKEY =
@"-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDpsDr+W45aFHIkvotZaGK/THlF
FpuZfUtghhWkHAm3H7yvL42J4xHrTr6IeUDCl4eKe6qiIgvYSNoL3u4SERGOeYmV
1F+cocu9IMGnNoicbh1zVW6e8/iGT3xaYQizJoVuWA/TC/zdds2ihCJfHDBDsouO
CXecPapyWCGQNsH5sQIDAQAB
-----END PUBLIC KEY-----";

const string PRIVATEKEY =
@"-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----";

#endregion

static void Main(string[] args)
{

TestSignAndVerify();

}

public static void TestSignAndVerify()
{
//sign
RSAParameters para = PemConverter.ConvertFromPemPrivateKey(PRIVATEKEY);
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
rsa.ImportParameters(para);
byte[] testData = Encoding.UTF8.GetBytes("hello");
MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
byte[] signData = rsa.SignData(testData, md5);

//verify
RSAParameters paraPub = PemConverter.ConvertFromPemPublicKey(PUBLICKEY);
RSACryptoServiceProvider rsaPub = new RSACryptoServiceProvider();
rsaPub.ImportParameters(paraPub);
if (rsaPub.VerifyData(testData, md5, signData))
{
Console.WriteLine("ok");
}
else
{
Console.WriteLine("no");
}

}

}
}

作者 THINK(谭振林)