c# 字符串 加密解密

在 C# 中，可以使用许多不同的加密算法来加密和解密字符串。这里介绍两种常用的加密算法：AES 和 RSA。

AES 加密和解密字符串的代码示例：

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

class AesExample
{
    static void Main()
    {
        string original = "Hello World!";
        byte[] key = new byte[32];
        byte[] iv = new byte[16];

        using (Aes aes = Aes.Create())
        {
            aes.Key = key;
            aes.IV = iv;

            // Encrypt the string to an array of bytes.
            byte[] encrypted = EncryptStringToBytes_Aes(original, aes.Key, aes.IV);

            // Decrypt the bytes to a string.
            string roundtrip = DecryptStringFromBytes_Aes(encrypted, aes.Key, aes.IV);

            //Display the original data and the decrypted data.
            Console.WriteLine("Original:   {0}", original);
            Console.WriteLine("Round Trip: {0}", roundtrip);
        }
    }

    static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
    {
        // Check arguments.
        if (plainText == null || plainText.Length <= 0)
            throw new ArgumentNullException("plainText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("IV");
        byte[] encrypted;
        // Create an Aes object
        // with the specified key and IV.
        using (Aes aes = Aes.Create())
        {
            aes.Key = Key;
            aes.IV = IV;

            // Create an encryptor to perform the stream transform.
            ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);

            // Create the streams used for encryption.
            using (MemoryStream msEncrypt = new MemoryStream())
            {
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {
                        //Write all data to the stream.
                        swEncrypt.Write(plainText);
                    }
                    encrypted = msEncrypt.ToArray();
                }
            }
        }

        // Return the encrypted bytes from the memory stream.
        return encrypted;
    }

    static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
    {
        // Check arguments.
        if (cipherText == null || cipherText.Length <= 0)
            throw new ArgumentNullException("cipherText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("IV");

        // Declare the string used to hold
        // the decrypted text.
        string plaintext = null;

        // Create an Aes object
        // with the specified key and IV.
        using (Aes aes = Aes.Create())
        {
            aes.Key = Key;
            aes.IV = IV;

            // Create a decryptor to perform the stream transform.
            ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV);

            // Create the streams used for decryption.
            using (MemoryStream msDecrypt = new MemoryStream(cipherText))
            {
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {

                        // Read the decrypted bytes from the decrypting stream
                        // and place them in a string.
                        plaintext = srDecrypt.ReadToEnd();
                    }
                }
            }
        }

        return plaintext;

    }
}

RSA 加密和解密字符串的代码示例：

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

class RSACSPSample
{
    static void Main()
    {
        // Create a new instance of RSACryptoServiceProvider
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();

        //Export the key information to an RSAParameters object.
        //Pass false to export the public key information or pass
        //true to export public and private key information.
        RSAParameters RSAParams = rsa.ExportParameters(false);

        //Create some data to sign and verify.
        byte[] data = Encoding.UTF8.GetBytes("Data to Sign");

        try
        {
            //Sign the data using the private key.
            byte[] signature = SignData(data, RSAParams);

            //Verify the data using the public key.
            bool verified = VerifyData(data, signature, RSAParams);

            Console.WriteLine("Data verified: {0}", verified);
        }
        catch (CryptographicException e)
        {
            Console.WriteLine(e.Message);
        }
    }

    static byte[] SignData(byte[] data, RSAParameters RSAParams)
    {
        try
        {
            //Create a new instance of RSACryptoServiceProvider.
            using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
            {
                //Import the RSA key information.
                rsa.ImportParameters(RSAParams);

                //Sign the data.
                return rsa.SignData(data, SHA256.Create());
            }
        }
        catch (CryptographicException e)
        {
            Console.WriteLine(e.Message);

            return null;
        }
    }

    static bool VerifyData(byte[] data, byte[] signature, RSAParameters RSAParams)
    {
        try
        {
            //Create a new instance of RSACryptoServiceProvider.
            using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
            {
                //Import the RSA key information.
                rsa.ImportParameters(RSAParams);

                //Verify the data.
                return rsa.VerifyData(data, SHA256.Create(), signature);
            }
        }
        catch (CryptographicException e)
        {
            Console.WriteLine(e.Message);

            return false;
        }
    }
}

请注意，这些示例代码只是演示如何使用 AES 和 RSA 加密和解密字符串，并不一定适用于所有情况。在实际应用中，需要根据具体需求选择适当的加密算法和实现方式，并且需要采取额外的安全措施来保护加密密钥等敏感信息。