c# 实现RSA非对称加密算法
目录
- 公钥与私钥
- C#实现
公钥与私钥
公钥与私钥是成对的，一般的，我们认为的是公钥加密、私钥解密、私钥签名、公钥验证，有人说成私钥加密，公钥解密时不对的。
公钥与私钥的生成有多种方式，可以通过程序生成（下文具体实现），可以通过openssl工具：
# 生成一个私钥，推荐使用1024位的秘钥，秘钥以pem格式保存到-out参数指定的文件中，采用PKCS1格式
openssl genrsa -out rsa.pem 1024
# 生成与私钥对应的公钥，生成的是Subject Public Key，一般配合PKCS8格式私钥使用
openssl rsa -in rsa.pem -pubout -out rsa.pub
RSA生成公钥与私钥一般有两种格式：PKCS1和PKCS8，上面的命令生成的秘钥是PKCS1格式的，而公钥是Subject Public Key，一般配合PKCS8格式私钥使用，所以就可能会涉及到PKCS1和PKCS8之间的转换：
# PKCS1格式私钥转换为PKCS8格式私钥，私钥直接输出到-out参数指定的文件中
openssl pkcs8 -topk8 -inform PEM -in rsa.pem -outform pem -nocrypt -out rsa_pkcs8.pem
# PKCS8格式私钥转换为PKCS1格式私钥，私钥直接输出到-out参数指定的文件中
openssl rsa -in rsa_pkcs8.pem -out rsa_pkcs1.pem
# PKCS1格式公钥转换为PKCS8格式公钥，转换后的内容直接输出
openssl rsa -pubin -in rsa.pub -RSAPublicKey_out
# PKCS8格式公钥转换为PKCS1格式公钥，转换后的内容直接输出
openssl rsa -RSAPublicKey_in -pubout -in rsa.pub
现实中，我们往往从pem、crt、pfx文件获取公私和私钥，crt、pfx的制作可以参考：简单的制作ssl证书，并在nginx和IIS中使用，或者使用现成的：https://pan.baidu.com/s/1MJ5YmuZiLBnf-DfNR_6D7A (提取码：c6tj)，密码都是：123456
C#实现
为了方便读取pem、crt、pfx文件中的公私和私钥，这里我使用了第三方的包：Portable.BouncyCastle，可以使用NuGet安装：Install-Package Portable.BouncyCastle
接着，这里我封装了一个RsaHelper辅助类来实现各种RSA加密的过程：
using Org.BouncyCastle.Utilities.IO.Pem;
using System;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;
namespace ConsoleApp1
{
public class RsaHelper
{
#region key
/// <summary>
/// 将秘钥保存到Pem文件
/// </summary>
/// <param name="isPrivateKey"></param>
/// <param name="buffer"></param>
/// <param name="pemFileName"></param>
/// <returns></returns>
public static void WriteToPem(byte[] buffer, bool isPrivateKey, string pemFileName)
{
PemObject pemObject = new PemObject(isPrivateKey ? "RSA PRIVATE KEY" : "RSA PUBLIC KEY", buffer);
if (File.Exists(pemFileName))
{
File.Delete(pemFileName);
}
using (var fileStream = new FileStream(pemFileName, FileMode.OpenOrCreate, FileAccess.Write))
{
using (var sw = new StreamWriter(fileStream))
{
var writer = new PemWriter(sw);
writer.WriteObject(pemObject);
sw.Flush();
}
}
}
/// <summary>
/// 从Pem文件中读取秘钥
/// </summary>
/// <param name="pemFileName"></param>
/// <returns></returns>
public static byte[] ReadFromPem(string pemFileName)
{
using (var fileStream = new FileStream(pemFileName, FileMode.Open, FileAccess.Read))
{
using (var sw = new StreamReader(fileStream))
{
var writer = new PemReader(sw);
return writer.ReadPemObject().Content;
}
}
}
/// <summary>
/// 从xml中读取秘钥
/// </summary>
/// <param name="xml"></param>
/// <param name="isPrivateKey"></param>
/// <param name="usePkcs8"></param>
/// <returns></returns>
public static byte[] ReadFromXml(string xml, bool isPrivateKey, bool usePkcs8)
{
using (var rsa = new RSACryptoServiceProvider())
{
rsa.FromXmlString(xml);
if (isPrivateKey)
{
return usePkcs8 ? rsa.ExportPkcs8PrivateKey() : rsa.ExportRSAPrivateKey();
}
return usePkcs8 ? rsa.ExportSubjectPublicKeyInfo() : rsa.ExportRSAPublicKey();
}
}
/// <summary>
/// 将秘钥保存到xml中
/// </summary>
/// <param name="buffer"></param>
/// <param name="isPrivateKey"></param>
/// <param name="usePkcs8"></param>
/// <returns></returns>
public static string WriteToXml(byte[] buffer, bool isPrivateKey, bool usePkcs8)
{
using (var rsa = CreateRSACryptoServiceProvider(buffer, isPrivateKey, usePkcs8))
{
return rsa.ToXmlString(isPrivateKey);
}
}
/// <summary>
/// 获取RSA非对称加密的Key
/// </summary>
/// <param name="publicKey"></param>
/// <param name="privateKey"></param>
public static void GenerateRsaKey(bool usePKCS8, out byte[] publicKey, out byte[] privateKey)
{
using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
{
rsa.KeySize = 1024;//1024位
if (usePKCS8)
{
//使用pkcs8填充方式导出
publicKey = rsa.ExportSubjectPublicKeyInfo();//公钥
privateKey = rsa.ExportPkcs8PrivateKey();//私钥
}
else
{
//使用pkcs1填充方式导出
【文章转自：韩国cn2服务器 转载请保留连接】 publicKey = rsa.ExportRSAPublicKey();//公钥
privateKey = rsa.ExportRSAPrivateKey();//私钥
}
}
}
/// <summary>
/// 从Pfx文件获取RSA非对称加密的Key
/// </summary>
/// <param name="pfxFileName"></param>
/// <param name="publicKey"></param>
/// <param name="privateKey"></param>
public static void ReadFromPfx(string pfxFileName, string password, out byte[] publicKey, out byte[] privateKey)
{
X509Certificate2 x509Certificate2 = new X509Certificate2(pfxFileName, password, X509KeyStorageFlags.Exportable);
publicKey = x509Certificate2.GetRSAPublicKey().ExportRSAPublicKey();
privateKey = x509Certificate2.GetRSAPrivateKey().ExportRSAPrivateKey();
}
/// <summary>
/// 从Crt文件中读取公钥
/// </summary>
/// <param name="crtFileName"></param>
/// <param name="password"></param>
/// <returns></returns>
public static byte[] ReadPublicKeyFromCrt(string crtFileName, string password)
{
X509Certificate2 x509Certificate2 = new X509Certificate2(crtFileName, password, X509KeyStorageFlags.Exportable);
var publicKey = x509Certificate2.GetRSAPublicKey().ExportRSAPublicKey();
return publicKey;
}
#endregion
#region Pkcs1 and Pkcs8
/// <summary>
/// Pkcs1转Pkcs8
/// </summary>
/// <param name="isPrivateKey"></param>
/// <param name="buffer"></param>
/// <returns></returns>
public static byte[] Pkcs1ToPkcs8(bool isPrivateKey, byte[] buffer)
{
using (var rsa = new RSACryptoServiceProvider())
{
if (isPrivateKey)
{
rsa.ImportRSAPrivateKey(buffer, out _);
return rsa.ExportPkcs8PrivateKey();
}
else
{
rsa.ImportRSAPublicKey(buffer, out _);
return rsa.ExportSubjectPublicKeyInfo();
}
}
}
/// <summary>
/// Pkcs8转Pkcs1
/// </summary>
/// <param name="isPrivateKey"></param>
/// <param name="buffer"></param>
/// <returns></returns>
public static byte[] Pkcs8ToPkcs1(bool isPrivateKey, byte[] buffer)
{
using (var rsa = new RSACryptoServiceProvider())
{
if (isPrivateKey)
{
rsa.ImportPkcs8PrivateKey(buffer, out _);
return rsa.ExportRSAPrivateKey();
}
else
{
rsa.ImportSubjectPublicKeyInfo(buffer, out _);
return rsa.ExportRSAPublicKey();
}
}
}
#endregion
#region RSA
/// <summary>
/// 获取一个RSACryptoServiceProvider
/// </summary>
/// <param name="isPrivateKey"></param>
/// <param name="buffer"></param>
/// <param name="usePkcs8"></param>
/// <returns></returns>
public static RSACryptoServiceProvider CreateRSACryptoServiceProvider(byte[] buffer, bool isPrivateKey, bool usePkcs8 = false)
{
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
if (isPrivateKey)
{
if (usePkcs8)
rsa.ImportPkcs8PrivateKey(buffer, out _);
else
rsa.ImportRSAPrivateKey(buffer, out _);
}
else
{
if (usePkcs8)
rsa.ImportSubjectPublicKeyInfo(buffer, out _);
else
rsa.ImportRSAPublicKey(buffer, out _);
}
return rsa;
}
/// <summary>
/// RSA公钥加密
/// </summary>
/// <param name="value">待加密的明文</param>
/// <param name="publicKey">公钥</param>
/// <param name="usePkcs8">是否使用pkcs8填充</param>
/// <returns></returns>
public static string RsaEncrypt(string value, byte[] publicKey, bool usePkcs8 = false)
{
if (string.IsNullOrEmpty(value)) return value;
using (RSACryptoServiceProvider rsa = CreateRSACryptoServiceProvider(publicKey, false, usePkcs8))
{
var buffer = Encoding.UTF8.GetBytes(value);
buffer = rsa.Encrypt(buffer, false);
//使用hex格式输出数据
StringBuilder result = new StringBuilder();
foreach (byte b in buffer)
{
result.AppendFormat("{0:x2}", b);
}
return result.ToString();
//或者使用下面的输出
//return BitConverter.ToString(buffer).Replace("-", "").ToLower();
}
}
/// <summary>
/// RSA私钥解密
/// </summary>
/// <param name="value">密文</param>
/// <param name="privateKey">私钥</param>
/// <param name="usePkcs8">是否使用pkcs8填充</param>
/// <returns></returns>
public static string RsaDecrypt(string value, byte[] privateKey, bool usePkcs8 = false)
{
if (string.IsNullOrEmpty(value)) return value;
using (RSACryptoServiceProvider rsa = CreateRSACryptoServiceProvider(privateKey, true, usePkcs8))
{
//转换hex格式数据为byte数组
var buffer = new byte[value.Length / 2];
for (var i = 0; i < buffer.Length; i++)
{
buffer[i] = (byte)Convert.ToInt32(value.Substring(i * 2, 2), 16);
}
buffer = rsa.Decrypt(buffer, false);
return Encoding.UTF8.GetString(buffer);
}
}
/// <summary>
/// RSA私钥生成签名
/// </summary>
/// <param name="value">原始值</param>
/// <param name="publicKey">公钥</param>
/// <param name="halg">签名hash算法：SHA，SHA1，MD5，SHA256，SHA384，SHA512</param>
/// <param name="usePkcs8">是否使用pkcs8填充</param>
/// <returns></returns>
public static string Sign(string value, byte[] privateKey, string halg = "MD5", bool usePkcs8 = false)
{
if (string.IsNullOrEmpty(value)) return value;
using (RSACryptoServiceProvider rsa = CreateRSACryptoServiceProvider(privateKey, true, usePkcs8))
{
byte[] buffer = Encoding.UTF8.GetBytes(value);
buffer = rsa.SignData(buffer, HashAlgorithm.Create(halg));
//使用hex格式输出数据
StringBuilder result = new StringBuilder();
foreach (byte b in buffer)
{
result.AppendFormat("{0:x2}", b);
}
return result.ToString();
//或者使用下面的输出
//return BitConverter.ToString(buffer).Replace("-", "").ToLower();
}
}
/// <summary>
/// RSA公钥验证签名
/// </summary>
/// <param name="value">原始值</param>
/// <param name="publicKey">公钥</param>
/// <param name="signature">签名</param>
/// <param name="halg">签名hash算法：SHA，SHA1，MD5，SHA256，SHA384，SHA512</param>
/// <param name="usePkcs8">是否使用pkcs8填充</param>
/// <returns></returns>
public static bool Verify(string value, byte[] publicKey, string signature, string halg = "MD5", bool usePkcs8 = false)
{
if (string.IsNullOrEmpty(value)) return false;
using (RSACryptoServiceProvider rsa = CreateRSACryptoServiceProvider(publicKey, false, usePkcs8))
{
//转换hex格式数据为byte数组
var buffer = new byte[signature.Length / 2];
for (var i = 0; i < buffer.Length; i++)
{
buffer[i] = (byte)Convert.ToInt32(signature.Substring(i * 2, 2), 16);
}
return rsa.VerifyData(Encoding.UTF8.GetBytes(value), HashAlgorithm.Create(halg), buffer);
}
}
#endregion
}
}
可以使用生成RSA的公私秘钥：
//通过程序生成
RsaHelper.GenerateRsaKey(usePKCS8, out publicKey, out privateKey);
生成秘钥后，需要保存，一般保存到pem文件中：
//保存到Pem文件，filePath是文件目录
RsaHelper.WriteToPem(publicKey, false, Path.Combine(filePath, "rsa.pub"));
RsaHelper.WriteToPem(privateKey, true, Path.Combine(filePath, "rsa.pem"));
还以将公钥和私钥输出为xml格式:
//保存到xml中
string publicKeyXml = RsaHelper.WriteToXml(publicKey, false, usePKCS8);
string privateKeyXml = RsaHelper.WriteToXml(privateKey, true, usePKCS8);
保存到pem文件和xml中后，也可以从中读取：
//从Pem文件获取，filePath是文件目录
publicKey = RsaHelper.ReadFromPem(Path.Combine(filePath, "rsa.pub"));
privateKey = RsaHelper.ReadFromPem(Path.Combine(filePath, "rsa.pem"));
//从xml中读取
publicKey = RsaHelper.ReadFromXml(publicKeyXml, false, usePKCS8);
privateKey = RsaHelper.ReadFromXml(privateKeyXml, true, usePKCS8);
还可以从crt证书中读取公钥，而crt文件不包含私钥，因此需要单独获取私钥：
//从crt文件读取，filePath是文件目录
publicKey = RsaHelper.ReadPublicKeyFromCrt(Path.Combine(filePath, "demo.crt"), "");
privateKey = RsaHelper.ReadFromPem(Path.Combine(filePath, "demo.key"));
pfx文件中包含了公钥和私钥，可以很方便就读取到：
//从demo.pfx文件读取（demo.pfx采用的是pkcs1），filePath是文件目录
RsaHelper.ReadFromPfx(Path.Combine(filePath, "demo.pfx"), "123456", out publicKey, out privateKey);
有时候我们还可能需要进行秘钥的转换：
// Pkcs8格式公钥转换为Pkcs1格式公钥
publicKey = RsaHelper.Pkcs8ToPkcs1(false, publicKey);
// Pkcs8格式私钥转换为Pkcs1格式私钥
privateKey = RsaHelper.Pkcs8ToPkcs1(true, privateKey);
// Pkcs1格式公钥转换为Pkcs8格式公钥
publicKey = RsaHelper.Pkcs1ToPkcs8(false, publicKey);
// Pkcs1格式私钥转换为Pkcs8格式私钥
privateKey = RsaHelper.Pkcs1ToPkcs8(true, privateKey);
有了公钥和私钥，接下就就能实现加密、解密、签名、验证签名等操作了：
string encryptText = RsaHelper.RsaEncrypt(text, publicKey, usePKCS8);
Console.WriteLine($"【{text}】经过【RSA】加密后：{encryptText}");
string decryptText = RsaHelper.RsaDecrypt(encryptText, privateKey, usePKCS8);
Console.WriteLine($"【{encryptText}】经过【RSA】解密后：{decryptText}");
string signature = RsaHelper.Sign(text, privateKey, "MD5", usePKCS8);
Console.WriteLine($"【{text}】经过【RSA】签名后：{signature}");
bool result = RsaHelper.Verify(text, publicKey, signature, "MD5", usePKCS8);
Console.WriteLine($"【{text}】的签名【{signature}】经过【RSA】验证后结果是：{result}");
完整的demo代码：
using System;
using System.IO;
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
string text = "上山打老虎";
bool usePKCS8 = true;// usePKCS8=true表示是否成PKCS8格式的公私秘钥,否则乘车PKCS1格式的公私秘钥
string filePath = Directory.GetCurrentDirectory();
Console.WriteLine($"文件路径：{filePath}");// 存放pem,crt,pfx等文件的目录
byte[] publicKey, privateKey;// 公钥和私钥
//通过程序生成
RsaHelper.GenerateRsaKey(usePKCS8, out publicKey, out privateKey);
//从Pem文件获取，filePath是文件目录
//publicKey = RsaHelper.ReadFromPem(Path.Combine(filePath, "rsa.pub"));
//privateKey = RsaHelper.ReadFromPem(Path.Combine(filePath, "rsa.pem"));
//从demo.pfx文件读取（demo.pfx采用的是pkcs1），filePath是文件目录
//RsaHelper.ReadFromPfx(Path.Combine(filePath, "demo.pfx"), "123456", out publicKey, out privateKey);
//从crt文件读取，filePath是文件目录
//publicKey = RsaHelper.ReadPublicKeyFromCrt(Path.Combine(filePath, "demo.crt"), "");
//privateKey = RsaHelper.ReadFromPem(Path.Combine(filePath, "demo.key"));
//保存到Pem文件，filePath是文件目录
RsaHelper.WriteToPem(publicKey, false, Path.Combine(filePath, "rsa.pub"));
RsaHelper.WriteToPem(privateKey, true, Path.Combine(filePath, "rsa.pem"));
//保存到xml中
string publicKeyXml = RsaHelper.WriteToXml(publicKey, false, usePKCS8);
string privateKeyXml = RsaHelper.WriteToXml(privateKey, true, usePKCS8);
//从xml中读取
publicKey = RsaHelper.ReadFromXml(publicKeyXml, false, usePKCS8);
privateKey = RsaHelper.ReadFromXml(privateKeyXml, true, usePKCS8);
// Pkcs8格式公钥转换为Pkcs1格式公钥
publicKey = RsaHelper.Pkcs8ToPkcs1(false, publicKey);
// Pkcs8格式私钥转换为Pkcs1格式私钥
privateKey = RsaHelper.Pkcs8ToPkcs1(true, privateKey);
// Pkcs1格式公钥转换为Pkcs8格式公钥
publicKey = RsaHelper.Pkcs1ToPkcs8(false, publicKey);
// Pkcs1格式私钥转换为Pkcs8格式私钥
privateKey = RsaHelper.Pkcs1ToPkcs8(true, privateKey);
string encryptText = RsaHelper.RsaEncrypt(text, publicKey, usePKCS8);
Console.WriteLine($"【{text}】经过【RSA】加密后：{encryptText}");
string decryptText = RsaHelper.RsaDecrypt(encryptText, privateKey, usePKCS8);
Console.WriteLine($"【{encryptText}】经过【RSA】解密后：{decryptText}");
string signature = RsaHelper.Sign(text, privateKey, "MD5", usePKCS8);
Console.WriteLine($"【{text}】经过【RSA】签名后：{signature}");
bool result = RsaHelper.Verify(text, publicKey, signature, "MD5", usePKCS8);
Console.WriteLine($"【{text}】的签名【{signature}】经过【RSA】验证后结果是：{result}");
}
}
}
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