csharp 使用pem密钥的本地文件RSA加密解密信息，以及SHA256的签名与验签代码

以下是使用 C# 语言使用 PEM 密钥的本地文件 RSA 加密解密信息，以及 SHA256 的签名与验签代码：

加密：

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public static string Encrypt(string publicKeyPath, string plainText)
{
    var rsa = new RSACryptoServiceProvider();
    var publicKey = File.ReadAllText(publicKeyPath);
    rsa.FromXmlString(publicKey);

    var plainBytes = Encoding.UTF8.GetBytes(plainText);
    var encryptedBytes = rsa.Encrypt(plainBytes, false);

    return Convert.ToBase64String(encryptedBytes);
}

解密：

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public static string Decrypt(string privateKeyPath, string encryptedText)
{
    var rsa = new RSACryptoServiceProvider();
    var privateKey = File.ReadAllText(privateKeyPath);
    rsa.FromXmlString(privateKey);

    var encryptedBytes = Convert.FromBase64String(encryptedText);
    var plainBytes = rsa.Decrypt(encryptedBytes, false);

    return Encoding.UTF8.GetString(plainBytes);
}

签名：

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public static string Sign(string privateKeyPath, string plainText)
{
    var rsa = new RSACryptoServiceProvider();
    var privateKey = File.ReadAllText(privateKeyPath);
    rsa.FromXmlString(privateKey);

    var plainBytes = Encoding.UTF8.GetBytes(plainText);
    var signatureBytes = rsa.SignData(plainBytes, new SHA256CryptoServiceProvider());

    return Convert.ToBase64String(signatureBytes);
}

验签：

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public static bool Verify(string publicKeyPath, string plainText, string signatureText)
{
    var rsa = new RSACryptoServiceProvider();
    var publicKey = File.ReadAllText(publicKeyPath);
    rsa.FromXmlString(publicKey);

    var plainBytes = Encoding.UTF8.GetBytes(plainText);
    var signatureBytes = Convert.FromBase64String(signatureText);

    return rsa.VerifyData(plainBytes, new SHA256CryptoServiceProvider(), signatureBytes);
}

注意：以上代码仅供参考，实际使用时需要根据具体情况进行修改和调整。