解密包含私钥的密码保护PEM

Question

public string GetPrivateKey(AsymmetricCipherKeyPair keyPair, string password)
{
    var generator = new Pkcs8Generator(keyPair.Private, Pkcs8Generator.PbeSha1_3DES);
    generator.IterationCount = 4;
    generator.Password = password.ToCharArray();
    var pem = generator.Generate();

    TextWriter textWriter = new StringWriter();
    PemWriter pemWriter = new PemWriter(textWriter);
    pemWriter.WriteObject(pem);
    pemWriter.Writer.Flush();
    string privateKey = textWriter.ToString();
    return privateKey;
}

-----BEGIN ENCRYPTED PRIVATE KEY-----
...
-----END ENCRYPTED PRIVATE KEY-----

PEMException：创建加密私钥时出现问题：System.NullReferenceException：对象引用未设置为对象的实例。在org.bouncycastle.openssl.pemreader.readprivateKey（PemObject PemObject）

下面是Decrypt方法的代码：

public string Decrypt(string base64Input, string privateKey, string password)
{
    var bytesToDecrypt = Convert.FromBase64String(base64Input);

    //get a stream from the string
    AsymmetricCipherKeyPair keyPair;
    var decryptEngine = new Pkcs1Encoding(new RsaEngine());

    using (var txtreader = new StringReader(privateKey))
    {
        var obj = new PemReader(txtreader).ReadObject();
        keyPair = (AsymmetricCipherKeyPair) obj;

        decryptEngine.Init(false, keyPair.Private);
    }

    var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
    return decrypted;
}

Answer 1

在我看来，你需要解密私钥才能使用它。当前未使用密码参数。不幸的是，要弄清楚如何做到这一点似乎并不那么容易。

Bouncy Castle和许多其他Java API一样，使用密码处理程序来检索密码。这样做的原因是允许程序仅在需要时才向用户询问密码。这允许程序将密码保留在内存中的时间最短。

因此,要允许解密,请使用以下构造函数：

PemReader(TextReader reader, IPasswordFinder pFinder);

通过IPasswordFinder的实现(C#的Bouncy Castle主要是一个Java端口，否则可能会使用委托）。

导入语句：

using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Prng;
using Org.BouncyCastle.OpenSsl;
using Org.BouncyCastle.Security;
using System.IO;

解码器：

private static AsymmetricCipherKeyPair DecodePrivateKey(string encryptedPrivateKey, string password)
{
    TextReader textReader = new StringReader(encryptedPrivateKey);
    PemReader pemReader = new PemReader(textReader, new PasswordFinder(password));
    object privateKeyObject = pemReader.ReadObject();
    RsaPrivateCrtKeyParameters rsaPrivatekey = (RsaPrivateCrtKeyParameters)privateKeyObject;
    RsaKeyParameters rsaPublicKey = new RsaKeyParameters(false, rsaPrivatekey.Modulus, rsaPrivatekey.PublicExponent);
    AsymmetricCipherKeyPair kp = new AsymmetricCipherKeyPair(rsaPublicKey, rsaPrivatekey);
    return kp;
}

必需的帮助程序类：

private class PasswordFinder : IPasswordFinder
{
    private string password;

    public PasswordFinder(string password)
    {
        this.password = password;
    }


    public char[] GetPassword()
    {
        return password.ToCharArray();
    }
}