Question

我正在尝试使用C＃读取仅包含RSA公钥的.pem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();

然而，代码会抛出InvalidCastException消息

无法投射类型的对象输入'Org.BouncyCastle.Crypto.Parameters.DsaPublicKeyParameters' 'Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair'。

如果没有私钥信息，我如何使用Bouncy Castle的PemReader只读取公钥？

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

这是一个可以将公共和私有PEM文件读入RSACryptoServiceProvider的可能解决方案：

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。

Answer 3

在回答c0d3Junk13时，我对PEM私钥有同样的问题，整个下午我都花了很多时间才找到使用C＃BouncyCastle 1.7版和Visual Studio 2013 Desktop Express的解决方案。不要忘记将项目引用添加到BouncyCastle.Crypto.dll

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Collections;
using System.IO;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Signers;
using Org.BouncyCastle.X509;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Utilities.Collections;
using Org.BouncyCastle.Utilities.Encoders;
using Org.BouncyCastle.Crypto; 
using Org.BouncyCastle.Crypto.Engines; 
using Org.BouncyCastle.OpenSsl;

/* 
    For an Active Directory generated pem, strip out everything in pem file before line:
    "-----BEGIN PRIVATE KEY-----" and re-save.
*/
string privateKeyFileName = @"C:\CertificateTest\CS\bccrypto-net-1.7-bin\private_key3.pem";

TextReader reader = File.OpenText(privateKeyFileName);

Org.BouncyCastle.Crypto.Parameters.RsaPrivateCrtKeyParameters key;

using (reader = File.OpenText(privateKeyFileName))
{
    key = (Org.BouncyCastle.Crypto.Parameters.RsaPrivateCrtKeyParameters)new PemReader(reader).ReadObject();
}

cipher.Init(false, key);

//Decrypting the input bytes

byte[] decipheredBytes = cipher.ProcessBlock(cipheredBytes, 0, cipheredBytes.Length);

MessageBox.Show(Encoding.UTF8.GetString(decipheredBytes));

Answer 4

代替：

keyPair = (Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair)new Org.BouncyCastle.OpenSsl.PemReader(reader).ReadObject();

使用：

keyPair = (Org.BouncyCastle.Crypto.AsymmetricKeyParameter)new Org.BouncyCastle.OpenSsl.PemReader(reader).ReadObject();

由于您仅使用公共密钥，并且实际上没有一对密钥（公共和私有），因此无法将其强制转换为“ AsymmetricCipherKeyPair”，因此应将其强制转换为“ AsymmetricKeyParameter”。

Answer 5

尝试以下代码：

Using Org.BouncyCastle.Crypto;


string path = HttpContext.Current.Server.MapPath(@"~\key\ABCD.pem");



AsymmetricCipherKeyPair Key;

TextReader tr = new StreamReader(@path);

 PemReader pr = new PemReader(tr);
        Key = (AsymmetricCipherKeyPair)pr.ReadObject();
        pr.Reader.Close();
        tr.Close();



         AsymmetricKeyParameter keaa = Key.Public;

Answer 6

编辑：看起来这取决于您使用的密钥文件类型。对于 ssh-keygen 密钥，私钥似乎具有AsymmetricCipherKeyPair类型，但是对于 openssl 密钥，私钥具有{{1 }}。

Bryan Jyh Herng Chong的答案似乎不再对我有用（至少在Bouncy Castle版本v1.8.5中）。看来RsaPrivateCrtKeyParameters的公钥和私钥PEM对象的设置不再相同。看来，使用kp.GetType().GetProperty("Private")返回的对象现在直接是PemReader.ReadObject()对象，因此不再需要先强制转换RsaPrivateCrtKeyParameters对象。

我将该行更改为此行，它就像一种魅力：

AsymmetricCipherKeyPair

仅使用Bouncy Castle阅读PEM RSA公钥

6 个答案: