使用 Bouncy Castle 进行 C# RSA 解密

2022-01-10 00:00:00 cryptography rsa c# bouncycastle java

我得到了一个 Base64 编码的加密字符串，它是在 Java 中使用 Bouncy Castle 加密的.下面的示例 Java 代码段:

I have been given a Base64 Encoded encrypted string, which was encrypted in Java using Bouncy Castle. Example Java snippet below:

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, key.getPublic());
byte[] encryptedText = cipher.doFinal("xxxxx|xxxxx".getBytes("UTF-8"));
String encodedText = new BASE64Encoder().encode(encryptedText);

我需要使用 Bouncy Castle 解密生成的字符串，但在 C# 中我已经获得了有关如何在 Java 中执行此操作的代码片段，但我无法将其转换为 C#(原因是我们正在构建一个 .net 站点，并且将成为 Java 站点中的 iFrame.Java 站点将 RSA 加密字符串传递给 .NET 站点).下面要解密的示例 Java 代码:

I need to decrypt the resulting string using Bouncy Castle, but in C# I have been given a code snippet on how to do this in Java, but I can't convert this for C# (reasons is we are building a .net site, and is going to be an iFrame within a Java site. The Java site is going to passing in the RSA Encrypted string to the .NET site). Example Java code to decrypt below:

Cipher cipherDec = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipherDec.init(Cipher.DECRYPT_MODE, key.getPrivate());
byte[] decodedText = new BASE64Decoder().decodeBuffer(encodedText);
byte[] decryptedText = cipherDec.doFinal(decodedText);
String finalValue = new String(decryptedText, "UTF-8");

我已经从 http://www.bouncycastle.org/csharp/ 下载了示例，但是似乎没有输入字符串值进行加密的示例，然后通过加密/解密过程.

I have downloaded the examples from http://www.bouncycastle.org/csharp/ but there doesn't seem to be an example of inputting a string value to get encrypted, and it then going though the encrypt/decrypt process.

我得到了 模数、公共指数、私人指数、素数P、的值>prime q、prime exponent p、prime exponent q和crt coefficient.

I have been given values for modulus, public exponent, private expontent, prime P, prime q, prime exponent p, prime exponent q and crt coefficient.

我已经看到我可以使用以下内容:

I have seen that I can use the following:

IAsymmetricBlockCipher signer = new Pkcs1Encoding(new RsaEngine());
signer.Init(true, pubParameters);

但是 signer 对象似乎没有与上面的 Java 示例相同的方法.

But the signer object doesn't seem to have the same methods as the Java examples above.

我唯一能用的方法是

ProcessBlock(byte[] inbuf, int inOff, int inLen);

但我看不出如何在我的上下文中使用它.

But I can't see how to use this in my context.

这里的任何帮助将不胜感激.

Any help here would be most appreciated.

推荐答案

为了帮助别人，最终转换的代码如下:

To Help others, the final code to convert is as follows:

RsaKeyParameters privParameters = new RsaPrivateCrtKeyParameters(mod, pubExp, privExp, p, q, pExp, qExp, crtCoef);
RsaKeyParameters pubParameters = new RsaKeyParameters(false, mod, pubExp);
IAsymmetricBlockCipher eng = new Pkcs1Encoding(new RsaEngine());
eng.Init(false, privParameters);
byte[] encdata = System.Convert.FromBase64String("{the enc string}");
encdata = eng.ProcessBlock(encdata, 0, encdata.Length);
string result = Encoding.UTF8.GetString(encdata);

mod、pubExp 等都是 BigInteger 值:

mod, pubExp etc etc are all BigInteger values:

static BigInteger mod = new BigInteger("big int value");

以下 using 指令是必需的:

The Following using directives are required:

using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Crypto.Encodings;
using Org.BouncyCastle.Math;

这可以从 bouncycastle 网站获得.http://www.bouncycastle.org/csharp/

Which can be obtained from the bouncycastle site. http://www.bouncycastle.org/csharp/

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