.NET Core加解密实战系列之——RSA非对称加密算法

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简介

加解密现状，编写此项目的背景：

  • 需要考虑系统环境兼容性问题（Linux、Windows）

  • 语言互通问题（如C#、Java）

  • 网上资料版本不一、不全面

  • .NET官方库密码算法提供不全面，很难针对其他语言（Java）进行适配

本系列文章主要介绍如何结合BouncyCastle在 .NET Core 中使用非对称加密算法、编码算法、哈希算法、对称加密算法、国密算法等一系列算法，内容篇幅代码居多（加解密算法相关的原理知识网上有很多，因此不过多介绍）。如有错误之处，还请大家批评指正。

功能依赖

BouncyCastle（https://www.bouncycastle.org/csharp） 是一个开放源码的轻量级密码术包；它支持大量的密码术算法，它提供了很多.NET Core标准库没有的算法。

支持.NET 4，.NET Standard 1.0-2.0，WP，Silverlight，Monoandroid，Xamarin.ios，.NET Core

功能 依赖
Portable.BouncyCastle Portable.BouncyCastle • 1.8.5

生成RSA秘钥

PKCS1格式

/// <summary>
/// PKCS1（非Java适用）
/// </summary>
/// <param name="keySize">密钥长度”一般只是指模值的位长度。目前主流可选值：1024、2048、3072、4096...</param>
/// <param name="format">PEM格式</param>
/// <returns></returns>
public RSAKeyParameter Pkcs1(int keySize, bool format=false)
{
var keyGenerator = GeneratorUtilities.GetKeyPairGenerator("RSA");
keyGenerator.Init(new KeyGenerationParameters(new SecureRandom(), keySize));

var keyPair = keyGenerator.GenerateKeyPair();

var subjectPublicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair.Public);
var privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(keyPair.Private);

if (!format)
{
return new RSAKeyParameter
{
PrivateKey = Base64.ToBase64String(privateKeyInfo.ParsePrivateKey().GetEncoded()),
PublicKey = Base64.ToBase64String(subjectPublicKeyInfo.GetEncoded())
};
}

var rsaKey = new RSAKeyParameter();
using (var sw = new StringWriter())
{
var pWrt = new PemWriter(sw);
pWrt.WriteObject(keyPair.Private);
pWrt.Writer.Close();
rsaKey.PrivateKey = sw.ToString();
}

using (var sw = new StringWriter())
{
var pWrt = new PemWriter(sw);
pWrt.WriteObject(keyPair.Public);
pWrt.Writer.Close();
rsaKey.PublicKey = sw.ToString();
}

return rsaKey;
}

PKCS8格式

/// <summary>
/// PKCS8（JAVA适用）
/// </summary>
/// <param name="keySize">密钥长度”一般只是指模值的位长度。目前主流可选值：1024、2048、3072、4096...</param>
/// <param name="format">PEM格式</param>
/// <returns></returns>
public RSAKeyParameter Pkcs8(int keySize, bool format=false)
{
var keyGenerator = GeneratorUtilities.GetKeyPairGenerator("RSA");
keyGenerator.Init(new KeyGenerationParameters(new SecureRandom(), keySize));
var keyPair = keyGenerator.GenerateKeyPair();

var subjectPublicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair.Public);
var privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(keyPair.Private);

if (!format)
{
return new RSAKeyParameter
{
PrivateKey = Base64.ToBase64String(privateKeyInfo.GetEncoded()),
PublicKey = Base64.ToBase64String(subjectPublicKeyInfo.GetEncoded())
};
}

var rsaKey = new RSAKeyParameter();
using (var sw = new StringWriter())
{
var pWrt = new PemWriter(sw);
var pkcs8 = new Pkcs8Generator(keyPair.Private);
pWrt.WriteObject(pkcs8);
pWrt.Writer.Close();
rsaKey.PrivateKey = sw.ToString();
}

using (var sw = new StringWriter())
{
var pWrt = new PemWriter(sw);
pWrt.WriteObject(keyPair.Public);
pWrt.Writer.Close();
rsaKey.PublicKey = sw.ToString();
}

return rsaKey;
}

私钥操作

PKCS1与PKCS8格式互转

仅私钥有PKCS1和PKCS8之分，公钥无格式区别。

/// <summary>
/// Pkcs1>>Pkcs8
/// </summary>
/// <param name="privateKey">Pkcs1私钥</param>
/// <param name="format">是否转PEM格式</param>
/// <returns></returns>
public static string PrivateKeyPkcs1ToPkcs8(string privateKey, bool format = false)
 {
var akp = RSAUtilities.GetAsymmetricKeyParameterFormPrivateKey(privateKey);
if (format)
{
var sw = new StringWriter();
var pWrt = new PemWriter(sw);
var pkcs8 = new Pkcs8Generator(akp);
pWrt.WriteObject(pkcs8);
pWrt.Writer.Close();
return sw.ToString();
}
else
{
var privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(akp);
return Base64.ToBase64String(privateKeyInfo.GetEncoded());
}
}
/// <summary>
/// Pkcs8>>Pkcs1
/// </summary>
/// <param name="privateKey">Pkcs8私钥</param>
/// <param name="format">是否转PEM格式</param>
/// <returns></returns>
public static string PrivateKeyPkcs8ToPkcs1(string privateKey, bool format = false)
{
var akp = RSAUtilities.GetAsymmetricKeyParameterFormAsn1PrivateKey(privateKey);
if (format)
{
var sw = new StringWriter();
var pWrt = new PemWriter(sw);
pWrt.WriteObject(akp);
pWrt.Writer.Close();
return sw.ToString();
}
else
{
var privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(akp);
return Base64.ToBase64String(privateKeyInfo.ParsePrivateKey().GetEncoded());
}
}

PKCS1与PKCS8私钥中提取公钥

/// <summary>
/// 从Pkcs1私钥中提取公钥
/// </summary>
/// <param name="privateKey">Pkcs1私钥</param>
/// <returns></returns>
public static string GetPublicKeyFromPrivateKeyPkcs1(string privateKey)
{
var instance = RsaPrivateKeyStructure.GetInstance(Base64.Decode(privateKey));

var publicParameter = (AsymmetricKeyParameter)new RsaKeyParameters(false, instance.Modulus,instance.PublicExponent);

var privateParameter = (AsymmetricKeyParameter)new RsaPrivateCrtKeyParameters(instance.Modulus,instance.PublicExponent, instance.PrivateExponent, instance.Prime1, instance.Prime2, instance.Exponent1,instance.Exponent2, instance.Coefficient);

var keyPair = new AsymmetricCipherKeyPair(publicParameter, privateParameter);
var subjectPublicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair.Public);

return Base64.ToBase64String(subjectPublicKeyInfo.GetEncoded());
}
/// <summary>
/// 从Pkcs8私钥中提取公钥
/// </summary>
/// <param name="privateKey">Pkcs8私钥</param>
/// <returns></returns>
public static string GetPublicKeyFromPrivateKeyPkcs8(string privateKey)
{
var privateKeyInfo = PrivateKeyInfo.GetInstance(Asn1Object.FromByteArray(Base64.Decode(privateKey)));
privateKey = Base64.ToBase64String(privateKeyInfo.ParsePrivateKey().GetEncoded());

var instance = RsaPrivateKeyStructure.GetInstance(Base64.Decode(privateKey));

var publicParameter = (AsymmetricKeyParameter)new RsaKeyParameters(false, instance.Modulus,instance.PublicExponent);

var privateParameter = (AsymmetricKeyParameter)new RsaPrivateCrtKeyParameters(instance.Modulus,instance.PublicExponent, instance.PrivateExponent, instance.Prime1, instance.Prime2, instance.Exponent1,instance.Exponent2, instance.Coefficient);

var keyPair = new AsymmetricCipherKeyPair(publicParameter, privateParameter);
var subjectPublicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair.Public);

return Base64.ToBase64String(subjectPublicKeyInfo.GetEncoded());
}

PEM操作

PEM格式密钥读取

public static string ReadPkcs1PrivateKey(string text)
{
if (!text.StartsWith("-----BEGIN RSA PRIVATE KEY-----"))
{
return text;
}

using (var reader = new StringReader(text))
{
var pr = new PemReader(reader);
var keyPair = pr.ReadObject() as AsymmetricCipherKeyPair;
pr.Reader.Close();

var privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(keyPair?.Private);
return Base64.ToBase64String(privateKeyInfo.ParsePrivateKey().GetEncoded());
}
}

public static string ReadPkcs8PrivateKey(string text)
{
if (!text.StartsWith("-----BEGIN PRIVATE KEY-----"))
{
return text;
}

using (var reader = new StringReader(text))
{
var pr = new PemReader(reader);
var akp = pr.ReadObject() as AsymmetricKeyParameter; ;
pr.Reader.Close();
return Base64.ToBase64String(PrivateKeyInfoFactory.CreatePrivateKeyInfo(akp).GetEncoded());
}
}

public static string ReadPublicKey(string text)
 {
if (!text.StartsWith("-----BEGIN PUBLIC KEY-----"))
{
return text;
}
using (var reader = new StringReader(text))
{
var pr = new PemReader(reader);
var keyPair = pr.ReadObject() as AsymmetricCipherKeyPair;
pr.Reader.Close();

var subjectPublicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair?.Public);
returnBase64.ToBase64String(subjectPublicKeyIno.GetEncoded());
}
}

PEM格式密钥写入

public static string WritePkcs1PrivateKey(string privateKey)
{
if (privateKey.StartsWith("-----BEGIN RSA PRIVATE KEY-----"))
{
return privateKey;
}

var akp = RSAUtilities.GetAsymmetricKeyParameterFormPrivateKey(privateKey);
using (var sw = new StringWriter())
{
var pWrt = new PemWriter(sw);
pWrt.WriteObject(akp);
pWrt.Writer.Close();
return sw.ToString();
}
}

public static string WritePkcs8PrivateKey(string privateKey)
{
if (privateKey.StartsWith("-----BEGIN PRIVATE KEY-----"))
{
return privateKey;
}

var akp = RSAUtilities.GetAsymmetricKeyParameterFormAsn1PrivateKey(privateKey);

using (var sw = new StringWriter())
{
var pWrt = new PemWriter(sw);
var pkcs8 = new Pkcs8Generator(akp);
pWrt.WriteObject(pkcs8);
pWrt.Writer.Close();
return sw.ToString();
}
}

public static string WritePublicKey(string publicKey)
{
if (publicKey.StartsWith("-----BEGIN PUBLIC KEY-----"))
{
return publicKey;
}
var akp = RSAUtilities.GetAsymmetricKeyParameterFormPublicKey(publicKey);
using (var sw = new StringWriter())
{
var pWrt = new PemWriter(sw);
pWrt.WriteObject(akp);
pWrt.Writer.Close();
return sw.ToString();
}
}

RSA加解密

获取非对称秘钥参数（AsymmetricKeyParameter）

/// <summary>
/// -----BEGIN RSA PRIVATE KEY-----
/// ...
/// -----END RSA PRIVATE KEY-----
/// </summary>
/// <param name="privateKey">Pkcs1格式私钥</param>
/// <returns></returns>
public static AsymmetricKeyParameter GetAsymmetricKeyParameterFormPrivateKey(string privateKey)
{
if (string.IsNullOrEmpty(privateKey))
{
throw new ArgumentNullException(nameof(privateKey));
}

var instance = RsaPrivateKeyStructure.GetInstance(Base64.Decode(privateKey));
return new RsaPrivateCrtKeyParameters(instance.Modulus, instance.PublicExponent, instance.PrivateExponent,instance.Prime1, instance.Prime2, instance.Exponent1, instance.Exponent2, instance.Coefficient);
}

/// <summary>
/// -----BEGIN PRIVATE KEY-----
/// ...
/// -----END PRIVATE KEY-----
/// </summary>
/// <param name="privateKey">Pkcs8格式私钥</param>
/// <returns></returns>
public static AsymmetricKeyParameter GetAsymmetricKeyParameterFormAsn1PrivateKey(string privateKey)
{
return PrivateKeyFactory.CreateKey(Base64.Decode(privateKey));
}

/// <summary>
/// -----BEGIN PUBLIC KEY-----
/// ...
/// -----END PUBLIC KEY-----
/// </summary>
/// <param name="publicKey">公钥</param>
/// <returns></returns>
public static AsymmetricKeyParameter GetAsymmetricKeyParameterFormPublicKey(string publicKey)
{
if (string.IsNullOrEmpty(publicKey))
{
throw new ArgumentNullException(nameof(publicKey));
}

return PublicKeyFactory.CreateKey(Base64.Decode(publicKey));
}

RSA加解与解密

/// <summary>
/// RSA加密
/// </summary>
/// <param name="data">未加密数据字节数组</param>
/// <param name="parameters">非对称密钥参数</param>
/// <param name="algorithm">密文算法</param>
/// <returns>已加密数据字节数组</returns>
public static byte[] Encrypt(byte[] data, AsymmetricKeyParameter parameters, string algorithm)
 {
if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
if (parameters == null)
{
throw new ArgumentNullException(nameof(parameters));
}
if (string.IsNullOrEmpty(algorithm))
{
throw new ArgumentNullException(nameof(algorithm));
}

var bufferedCipher = CipherUtilities.GetCipher(algorithm);
bufferedCipher.Init(true, parameters);
return bufferedCipher.DoFinal(data);
}

/// <summary>
/// RSA解密
/// </summary>
/// <param name="data">已加密数据字节数组</param>
/// <param name="parameters">非对称密钥参数</param>
/// <param name="algorithm">密文算法</param>
/// <returns>未加密数据字节数组</returns>
public static byte[] Decrypt(byte[] data, AsymmetricKeyParameter parameters, string algorithm)
{
if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
if (parameters == null)
{
throw new ArgumentNullException(nameof(parameters));
}
if (string.IsNullOrEmpty(algorithm))
{
throw new ArgumentNullException(nameof(algorithm));
}
var bufferedCipher = CipherUtilities.GetCipher(algorithm);
bufferedCipher.Init(false, parameters);
return bufferedCipher.DoFinal(data);
}

/// <summary>
/// RSA加密——Base64
/// </summary>
/// <param name="data">未加密字符串</param>
/// <param name="parameters">非对称密钥参数</param>
/// <param name="algorithm">密文算法</param>
/// <returns>已加密Base64字符串</returns>
public static string EncryptToBase64(string data, AsymmetricKeyParameter parameters, string algorithm)
 {
return Base64.ToBase64String(Encrypt(Encoding.UTF8.GetBytes(data), parameters, algorithm));
}

/// <summary>
/// RSA解密——Base64
/// </summary>
/// <param name="data">已加密Base64字符串</param>
/// <param name="parameters">非对称密钥参数</param>
/// <param name="algorithm">密文算法</param>
/// <returns>未加密字符串</returns>
public static string DecryptFromBase64(string data, AsymmetricKeyParameter parameters, string algorithm)
 {
return Encoding.UTF8.GetString(Decrypt(Base64.Decode(data), parameters, algorithm));
}

/// <summary>
/// RSA加密——十六进制
/// </summary>
/// <param name="data">未加密字符串</param>
/// <param name="parameters">非对称密钥参数</param>
/// <param name="algorithm">密文算法</param>
/// <returns>已加密十六进制字符串</returns>
public static string EncryptToHex(string data, AsymmetricKeyParameter parameters, string algorithm)
{
return Hex.ToHexString(Encrypt(Encoding.UTF8.GetBytes(data), parameters, algorithm));
}

/// <summary>
/// RSA解密——十六进制
/// </summary>
/// <param name="data">已加密十六进制字符串</param>
/// <param name="parameters">非对称密钥参数</param>
/// <param name="algorithm">密文算法</param>
/// <returns>未加密字符串</returns>
public static string DecryptFromHex(string data, AsymmetricKeyParameter parameters, string algorithm)
{
return Encoding.UTF8.GetString(Decrypt(Hex.Decode(data), parameters, algorithm));
}

RSA密文算法

public const string RSA_NONE_NoPadding = "RSA/NONE/NoPadding";
public const string RSA_NONE_PKCS1Padding = "RSA/NONE/PKCS1Padding";
public const string RSA_NONE_OAEPPadding = "RSA/NONE/OAEPPadding";
public const string RSA_NONE_OAEPWithSHA1AndMGF1Padding = "RSA/NONE/OAEPWithSHA1AndMGF1Padding";
public const string RSA_NONE_OAEPWithSHA224AndMGF1Padding = "RSA/NONE/OAEPWithSHA224AndMGF1Padding";
public const string RSA_NONE_OAEPWithSHA256AndMGF1Padding = "RSA/NONE/OAEPWithSHA256AndMGF1Padding";
public const string RSA_NONE_OAEPWithSHA384AndMGF1Padding = "RSA/NONE/OAEPWithSHA384AndMGF1Padding";
public const string RSA_NONE_OAEPWithMD5AndMGF1Padding = "RSA/NONE/OAEPWithMD5AndMGF1Padding";

public const string RSA_ECB_NoPadding = "RSA/ECB/NoPadding";
public const string RSA_ECB_PKCS1Padding = "RSA/ECB/PKCS1Padding";
public const string RSA_ECB_OAEPPadding = "RSA/ECB/OAEPPadding";
public const string RSA_ECB_OAEPWithSHA1AndMGF1Padding = "RSA/ECB/OAEPWithSHA1AndMGF1Padding";
public const string RSA_ECB_OAEPWithSHA224AndMGF1Padding = "RSA/ECB/OAEPWithSHA224AndMGF1Padding";
public const string RSA_ECB_OAEPWithSHA256AndMGF1Padding = "RSA/ECB/OAEPWithSHA256AndMGF1Padding";
public const string RSA_ECB_OAEPWithSHA384AndMGF1Padding = "RSA/ECB/OAEPWithSHA384AndMGF1Padding";
public const string RSA_ECB_OAEPWithMD5AndMGF1Padding = "RSA/ECB/OAEPWithMD5AndMGF1Padding";

......

编码算法

大家要明白，不管是对称算法还是非对称算法，其输入与输出均是字节数组，通常我们要结合编码算法对加密之后或解密之前的数据，进行编码操作。

BouncyCastle提供的Base64编码算法

namespace Org.BouncyCastle.Utilities.Encoders
{
public sealed class Base64
{
//
public static byte[] Decode(byte[] data);
//
public static byte[] Decode(string data);
//
public static int Decode(string data, Stream outStream);
//
public static byte[] Encode(byte[] data);
//
public static byte[] Encode(byte[] data, int off, int length);
//
public static int Encode(byte[] data, Stream outStream);
//
public static int Encode(byte[] data, int off, int length, Stream outStream);
public static string ToBase64String(byte[] data);
public static string ToBase64String(byte[] data, int off, int length);
}
}

BouncyCastle提供的Hex十六进制编码算法

namespace Org.BouncyCastle.Utilities.Encoders
{
//
// 摘要:
// Class to decode and encode Hex.
public sealed class Hex
{
//
public static byte[] Decode(byte[] data);
//
public static byte[] Decode(string data);
//
public static int Decode(string data, Stream outStream);
//
public static byte[] Encode(byte[] data);
//
public static byte[] Encode(byte[] data, int off, int length);
//
public static int Encode(byte[] data, Stream outStream);
//
public static int Encode(byte[] data, int off, int length, Stream outStream);
public static string ToHexString(byte[] data);
public static string ToHexString(byte[] data, int off, int length);
}
}

RSA加解密示例

private static void RSA_ECB_PKCS1Padding()
 {
var data = "hello rsa";

Console.WriteLine($"加密原文：{data}");

// rsa pkcs8 private key encrypt
//algorithm rsa/ecb/pkcs1padding
var pkcs8data = RSA.EncryptToBase64(data, RSAUtilities.GetAsymmetricKeyParameterFormAsn1PrivateKey(pkcs8_1024_private_key),CipherAlgorithms.RSA_ECB_PKCS1Padding);

Console.WriteLine("密钥格式：pkcs8，密文算法：rsa/ecb/pkcs1padding，加密结果");
Console.WriteLine(pkcs8data);

//rsa pkcs1 private key encrypt
//algorithm rsa/ecb/pkcs1padding
var pkcs1data = RSA.EncryptToBase64(data, RSAUtilities.GetAsymmetricKeyParameterFormPrivateKey(pkcs1_1024_private_key),CipherAlgorithms.RSA_ECB_PKCS1Padding);

Console.WriteLine($"密钥格式：pkcs1，密文算法：rsa/ecb/pkcs1padding");
Console.WriteLine(pkcs1data);

Console.WriteLine($"加密结果比对是否一致：{pkcs8data.Equals(pkcs1data)}");

var _1024_public_key = RSAKeyConverter.GetPublicKeyFromPrivateKeyPkcs1(pkcs1_1024_private_key);

Console.WriteLine($"从pkcs1私钥中提取公钥：");
Console.WriteLine(_1024_public_key);

Console.WriteLine("使用公钥解密数据：");
//rsa public key decrypt
//algorithm rsa/ecb/pkcs1padding
Console.WriteLine(RSA.DecryptFromBase64(pkcs1data, RSAUtilities.GetAsymmetricKeyParameterFormPublicKey(_1024_public_key),CipherAlgorithms.RSA_ECB_PKCS1Padding));

Console.WriteLine();
}


下期预告

下一篇将介绍哈希算法（HMACSHA1、HMACSHA256、SHA1、SHA1WithRSA、SHA256、SHA256WithRSA），敬请期待…


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