仅使用Bouncy Castle阅读PEM RSA公钥

Question

我正在尝试使用C#读取.pem仅包含RSA公钥的文件.我无权访问私钥信息,我的应用程序也不需要它.文件myprivatekey.pem文件以.开头

-----BEGIN PUBLIC KEY----- 最后以 -----END PUBLIC KEY-----.

我目前的代码如下:

    Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair keyPair;

    using (var reader = File.OpenText(@"c:\keys\myprivatekey.pem"))
        keyPair = (Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair)new Org.BouncyCastle.OpenSsl.PemReader(reader).ReadObject();

但是代码会抛出一条InvalidCastException消息

无法将"Org.BouncyCastle.Crypto.Parameters.DsaPublicKeyParameters"类型的对象强制转换为"Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair".

PemReader当没有私钥信息时,如何使用Bouncy Castle 只读公钥？

Answer 1

以下代码仅在给定文件名的情况下读取公钥.应该为任何生产代码更改异常处理.此方法返回一个AsymetricKeyParameter.

public Org.BouncyCastle.Crypto.AsymmetricKeyParameter ReadAsymmetricKeyParameter(string pemFilename)
{
    var fileStream = System.IO.File.OpenText (pemFilename);
    var pemReader = new Org.BouncyCastle.OpenSsl.PemReader (fileStream);
    var KeyParameter = (Org.BouncyCastle.Crypto.AsymmetricKeyParameter)pemReader.ReadObject ();
    return KeyParameter;
}

Answer 2

这是一个可能的解决方案,它将公共和私有PEM文件读入RSACryptoServiceProvider:

public class PemReaderB
{
    public static RSACryptoServiceProvider GetRSAProviderFromPem(String pemstr)
    {
        CspParameters cspParameters = new CspParameters();
        cspParameters.KeyContainerName = "MyKeyContainer";
        RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(cspParameters);

        Func<RSACryptoServiceProvider, RsaKeyParameters, RSACryptoServiceProvider> MakePublicRCSP = (RSACryptoServiceProvider rcsp, RsaKeyParameters rkp) =>
        {
            RSAParameters rsaParameters = DotNetUtilities.ToRSAParameters(rkp);
            rcsp.ImportParameters(rsaParameters);
            return rsaKey;
        };

        Func<RSACryptoServiceProvider, RsaPrivateCrtKeyParameters, RSACryptoServiceProvider> MakePrivateRCSP = (RSACryptoServiceProvider rcsp, RsaPrivateCrtKeyParameters rkp) =>
        {
            RSAParameters rsaParameters = DotNetUtilities.ToRSAParameters(rkp);
            rcsp.ImportParameters(rsaParameters);
            return rsaKey;
        };

        PemReader reader = new PemReader(new StringReader(pemstr));
        object kp = reader.ReadObject();

        // If object has Private/Public property, we have a Private PEM
        return (kp.GetType().GetProperty("Private") != null) ? MakePrivateRCSP(rsaKey, (RsaPrivateCrtKeyParameters)(((AsymmetricCipherKeyPair)kp).Private)) : MakePublicRCSP(rsaKey, (RsaKeyParameters)kp);
    }

    public static RSACryptoServiceProvider GetRSAProviderFromPemFile(String pemfile)
    {
        return GetRSAProviderFromPem(File.ReadAllText(pemfile).Trim());
    }
}

希望这有助于某人.