C# BouncyCastle - 使用 Public/Private 密钥的 RSA 加密

Question

我需要在 C# 中加密数据以便将其传递给 Java。 Java 代码属于第 3 方，但我已获得相关来源，因此我决定由于 Java 使用 Bouncy Castle 库，我将使用 C# 端口。

解密工作正常。但是，只有当我使用私钥而不是 public 密钥进行加密时，解密才有效。使用 public 密钥时，解密失败 unknown block type.

显然RsaEncryptWithPrivate里面的加密在加密时使用了public密钥，所以我不明白为什么这两种加密方法在功能上不相同：

using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Encodings;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.OpenSsl;

public class EncryptionClass
{       
    public string RsaEncryptWithPublic(string clearText
        , string publicKey)
    {
        var bytesToEncrypt = Encoding.UTF8.GetBytes(clearText);

        var encryptEngine = new Pkcs1Encoding(new RsaEngine());

        using (var txtreader = new StringReader(publicKey))
        {
            var keyParameter = (AsymmetricKeyParameter)new PemReader(txtreader).ReadObject();

            encryptEngine.Init(true, keyParameter);
        }

        var encrypted = Convert.ToBase64String(encryptEngine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length));
        return encrypted;

    }

    public string RsaEncryptWithPrivate(string clearText
        , string privateKey)
    {
        var bytesToEncrypt = Encoding.UTF8.GetBytes(clearText);

        var encryptEngine = new Pkcs1Encoding(new RsaEngine());

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

            encryptEngine.Init(true, keyPair.Public);
        }

        var encrypted= Convert.ToBase64String(encryptEngine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length));
        return encrypted;
    }


    // Decryption:

    public string RsaDecrypt(string base64Input
        , string privateKey)
    {
        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) )
        {
            keyPair = (AsymmetricCipherKeyPair) new PemReader(txtreader).ReadObject();

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

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

// In my test project   

    [Test()]
    public void EncryptTest()
    {
        // Set up 
        var input = "Perceived determine departure explained no forfeited";
        var enc = new EncryptionClass();
        var publicKey = "-----BEGIN PUBLIC KEY----- // SNIPPED // -----END PUBLIC KEY-----";
        var privateKey = "-----BEGIN PRIVATE KEY----- // SNIPPED // -----END PRIVATE KEY-----";

        // Encrypt it
        var encryptedWithPublic = enc.RsaEncryptWithPublic(input, publicKey); 

        var encryptedWithPrivate = enc.RsaEncryptWithPrivate(input, privateKey);

        // Decrypt
        var outputWithPublic = payUEnc.RsaDecrypt(encryptedWithPrivate, privateKey); 
        // Throws error: "unknown block type"

        var outputWithPrivate = payUEnc.RsaDecrypt(encryptedWithPrivate, _privateKey); 
        // returns the correct decrypted text, "Perceived determine departure explained no forfeited"

        // Assertion
        Assert.AreEqual(outputWithPrivate, input); // This is true
    }

顺便说一下，Java 解密也出现了同样的问题 - 当仅使用 public 密钥加密时，它会失败。

我是密码学的新手，所以我确定我在 RsaEncryptWithPublic 方法中犯了一些非常简单的错误。

编辑：

我还添加了一个单元测试，证明 public 密钥等于从私钥中提取的 public 密钥：

    [Test()]
    public void EncryptCompareTest()
    {
        AsymmetricKeyParameter keyParameterFromPub;
        AsymmetricKeyParameter keyParameterFromPriv;
        AsymmetricCipherKeyPair keyPair;

        using (var txtreader = new StringReader(_publicKey))
        {
            keyParameterFromPub = (AsymmetricKeyParameter)new PemReader(txtreader).ReadObject();
        }

        using (var txtreader = new StringReader(_privateKey))
        {
            keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();
            keyParameterFromPriv = keyPair.Public;
        }

        Assert.AreEqual(keyParameterFromPub, keyParameterFromPriv); // returns true;

    }

Answer 1

我使用的 Public 密钥不正确.. 证明私钥和 Public 密钥匹配的测试使用的是正确的 Public 密钥。

只要你的密钥正确，上面的代码就可以完美运行！

Answer 2

OP 的代码中存在一些错误。我做了一些改变。这是我得到的运行.

public class TFRSAEncryption
{
    public string RsaEncryptWithPublic(string clearText, string publicKey)
    {
        var bytesToEncrypt = Encoding.UTF8.GetBytes(clearText);

        var encryptEngine = new Pkcs1Encoding(new RsaEngine());

        using (var txtreader = new StringReader(publicKey))
        {
            var keyParameter = (AsymmetricKeyParameter)new PemReader(txtreader).ReadObject();

            encryptEngine.Init(true, keyParameter);
        }

        var encrypted = Convert.ToBase64String(encryptEngine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length));
        return encrypted;

    }

    public string RsaEncryptWithPrivate(string clearText, string privateKey)
    {
        var bytesToEncrypt = Encoding.UTF8.GetBytes(clearText);

        var encryptEngine = new Pkcs1Encoding(new RsaEngine());

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

            encryptEngine.Init(true, keyPair.Private);
        }

        var encrypted = Convert.ToBase64String(encryptEngine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length));
        return encrypted;
    }


    // Decryption:

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

        AsymmetricCipherKeyPair keyPair;
        var decryptEngine = new Pkcs1Encoding(new RsaEngine());

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

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

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

    public string RsaDecryptWithPublic(string base64Input, string publicKey)
    {
        var bytesToDecrypt = Convert.FromBase64String(base64Input);

        var decryptEngine = new Pkcs1Encoding(new RsaEngine());

        using (var txtreader = new StringReader(publicKey))
        {
            var keyParameter = (AsymmetricKeyParameter)new PemReader(txtreader).ReadObject();

            decryptEngine.Init(false, keyParameter);
        }

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

class Program
{

    static void Main(string[] args)
    {
        // Set up 
        var input = "Perceived determine departure explained no forfeited";
        var enc = new TFRSAEncryption();
        var publicKey = "-----BEGIN PUBLIC KEY----- // Base64 string omitted // -----END PUBLIC KEY-----";
        var privateKey = "-----BEGIN PRIVATE KEY----- // Base64 string omitted// -----END PRIVATE KEY-----";

        // Encrypt it
        var encryptedWithPublic = enc.RsaEncryptWithPublic(input, publicKey);

        var encryptedWithPrivate = enc.RsaEncryptWithPrivate(input, privateKey);

        // Decrypt
        var output1 = enc.RsaDecryptWithPrivate(encryptedWithPublic, privateKey);

        var output2 = enc.RsaDecryptWithPublic(encryptedWithPrivate, publicKey);

        Console.WriteLine(output1 == output2 && output2 == input);

        Console.Read();
    }
}

Answer 3

我尝试了@Morio 的解决方案，但出现了一些异常。第一个是

-----END PUBLIC KEY not found

我能够通过正确格式化两个键来修复

publicKey = $"-----BEGIN PUBLIC KEY-----\n{publicKey}\n-----END PUBLIC KEY-----\n";

第二个错误是在尝试解密文本时出现的。 Unable to cast object of type 'Org.BouncyCastle.Crypto.Parameters.RsaPrivateCrtKeyParameters' to type 'Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair'.
我通过转换为适当的类型来解决这个问题。

var keyPair = (RsaPrivateCrtKeyParameters)new PemReader(txtreader).ReadObject();

C# BouncyCastle - 使用 Public/Private 密钥的 RSA 加密

C# BouncyCastle - RSA Encryption with Public/Private keys

c#

encryption

cryptography

rsa

bouncycastle