无法使用私钥将生成的证书导出到 .NET 4.0/4.5 中的字节数组

Question

我需要在字节数组中导出和导入带有私钥的生成证书，除非我使用 .NET 框架 4.0 和 4.5，否则我没有任何问题。我正在使用 BouncyCastle 库生成自签名证书，然后将它们转换为 .NET 格式（X509Certificate2 对象）。不幸的是，升级到最新框架后，我无法导出私钥。代码如下：

using System;
using System.Diagnostics;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Prng;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;

namespace X509CertificateExport
{
    class Program
    {
        static void Main(string[] args)
        {
            var certificate = Generate();
            var exported = certificate.Export(X509ContentType.Pfx);
            var imported = new X509Certificate2(exported, (string)null, X509KeyStorageFlags.Exportable | X509KeyStorageFlags.PersistKeySet);

            Console.WriteLine("Certificate has private key: " + imported.HasPrivateKey);
            Console.ReadKey();
        }

        public static X509Certificate2 Generate()
        {
            var keyPairGenerator = new RsaKeyPairGenerator();
            var secureRandom = new SecureRandom(new CryptoApiRandomGenerator());
            keyPairGenerator.Init(new KeyGenerationParameters(secureRandom, 1024));
            var keyPair = keyPairGenerator.GenerateKeyPair();
            var publicKey = keyPair.Public;
            var privateKey = (RsaPrivateCrtKeyParameters)keyPair.Private;

            var generator = new X509V3CertificateGenerator();
            generator.SetSerialNumber(BigInteger.ProbablePrime(120, new Random()));
            generator.SetSubjectDN(new X509Name("CN=Test"));
            generator.SetIssuerDN(new X509Name("CN=Test"));
            generator.SetNotAfter(DateTime.Now + new TimeSpan(10, 10, 10, 10));
            generator.SetNotBefore(DateTime.Now.Subtract(new TimeSpan(7, 0, 0, 0)));
            generator.SetSignatureAlgorithm("MD5WithRSA");
            generator.SetPublicKey(publicKey);

            var newCert = generator.Generate(privateKey);
            var dotNetPrivateKey = ToDotNetKey(privateKey);
            var dotNetCert = new X509Certificate2(DotNetUtilities.ToX509Certificate(newCert));
            dotNetCert.PrivateKey = dotNetPrivateKey;

            return dotNetCert;
        }

        public static AsymmetricAlgorithm ToDotNetKey(RsaPrivateCrtKeyParameters privateKey)
        {
            var rsaProvider = new RSACryptoServiceProvider();
            var parameters = new RSAParameters
            {
                Modulus = privateKey.Modulus.ToByteArrayUnsigned(),
                P = privateKey.P.ToByteArrayUnsigned(),
                Q = privateKey.Q.ToByteArrayUnsigned(),
                DP = privateKey.DP.ToByteArrayUnsigned(),
                DQ = privateKey.DQ.ToByteArrayUnsigned(),
                InverseQ = privateKey.QInv.ToByteArrayUnsigned(),
                D = privateKey.Exponent.ToByteArrayUnsigned(),
                Exponent = privateKey.PublicExponent.ToByteArrayUnsigned()
            };

            rsaProvider.ImportParameters(parameters);
            return rsaProvider;
        }
    }
}

仔细查看生成的证书后，我注意到 PrivateKey.CspKeyContainerInfo.Exportable 标志对于 .NET 框架 3.5 是正确的，但对于更高版本，它会抛出：

'Exportable' threw an exception of type
'System.Security.Cryptography.CryptographicException' / Key does not exist

我看到的唯一区别是 PrivateKey.CspKeyContainerInfo.m_parameters.Flags： .NET 3.5 - 'NoFlags'; .NET 4.5 - 'CreateEphemeralKey'。 文档指出“CreateEphemeralKey”创建了一个临时密钥，该密钥在关联的 RSA 对象关闭时释放。它是在 4.0 框架中引入的，之前并不存在。我试图通过显式创建 CspParameters 来摆脱这个标志：

public static AsymmetricAlgorithm ToDotNetKey(RsaPrivateCrtKeyParameters privateKey)
{
    var cspParams = new CspParameters
    {
        Flags = CspProviderFlags.UseMachineKeyStore
    };

    var rsaProvider = new RSACryptoServiceProvider(cspParams);
    // ...

但没有运气。无论如何都添加了“CreateEphemeralKey”，因此我得到了UseMachineKeyStore | CreateEphemeralKey 标志，但我不知道如何删除它。有没有办法可以忽略此标志并正常导出带有私钥的证书？

Answer 1

我没有注意到 CspKeyContainerInfo.CspParameters.KeyContainerName 在 .NET 4.0 和 .NET 4.5 中创建密钥后为空，但它是在 .NET 3.5 中自动生成的。我已经为容器设置了一个唯一的名称，现在我可以导出私钥了。

public static AsymmetricAlgorithm ToDotNetKey(RsaPrivateCrtKeyParameters privateKey)
{
    var cspParams = new CspParameters
    {
          KeyContainerName = Guid.NewGuid().ToString(),
          KeyNumber = (int)KeyNumber.Exchange,
          Flags = CspProviderFlags.UseMachineKeyStore
    };

    var rsaProvider = new RSACryptoServiceProvider(cspParams);
    // ...