vb6和c#中的AES加密

前言

在VB6和C#中实现AES加密算法是一种常见的需求。AES（Advanced Encryption Standard）是一种对称加密算法，使用相同的密钥用于加密和解密数据。本文将介绍如何在VB6和C#中使用AES加密算法。

VBA中的AES加密

VBA是VB6的一部分，可以使用Microsoft Enhanced Cryptographic Provider（CryptoAPI）来实现AES加密。首先，需要在代码中引用"Microsoft Enhanced Cryptographic Provider v1.0"。

Option Explicit

Private Sub Foo()
    Dim data As String
    Dim password As String
    Dim encryptedData As String
    Dim decryptedData As String
    
    data = "Hello, world!"
    password = "secretpassword"
    
    encryptedData = AESEncrypt(data, password)
    decryptedData = AESDecrypt(encryptedData, password)
    
    MsgBox "Encrypted data: " & encryptedData
    MsgBox "Decrypted data: " & decryptedData
End Sub

Private Function AESEncrypt(ByVal data As String, ByVal password As String) As String
    Dim provider As String
    Dim cryptoService As Object
    Dim passwordBytes() As Byte
    Dim dataToEncrypt() As Byte
    Dim encryptedBytes() As Byte
    Dim encryptedData As String
    
    provider = "Microsoft Enhanced Cryptographic Provider v1.0"
    
    Set cryptoService = CreateObject("CAPICOM.EncryptedData")
    cryptoService.Algorithm.Name = CAPICOM_ENCRYPTION_ALGORITHM_AES
    
    passwordBytes = StrConv(password, vbFromUnicode)
    dataToEncrypt = StrConv(data, vbFromUnicode)
    
    cryptoService.SetSecret passwordBytes
    encryptedBytes = cryptoService.Encrypt(dataToEncrypt)
    
    encryptedData = CryptBinaryToString(encryptedBytes)
    AESEncrypt = encryptedData
End Function

Private Function AESDecrypt(ByVal encryptedData As String, ByVal password As String) As String
    Dim provider As String
    Dim cryptoService As Object
    Dim passwordBytes() As Byte
    Dim encryptedBytes() As Byte
    Dim decryptedBytes() As Byte
    Dim decryptedData As String
    
    provider = "Microsoft Enhanced Cryptographic Provider v1.0"
    
    Set cryptoService = CreateObject("CAPICOM.EncryptedData")
    cryptoService.Algorithm.Name = CAPICOM_ENCRYPTION_ALGORITHM_AES
    
    passwordBytes = StrConv(password, vbFromUnicode)
    encryptedBytes = CryptStringToBinary(encryptedData)
    
    cryptoService.SetSecret passwordBytes
    decryptedBytes = cryptoService.Decrypt(encryptedBytes)
    
    decryptedData = StrConv(decryptedBytes, vbUnicode)
    AESDecrypt = decryptedData
End Function

Private Function CryptBinaryToString(ByVal binData() As Byte) As String
    Dim i As Long
    Dim result As String
    
    For i = LBound(binData) To UBound(binData)
        result = result & Right("0" & Hex(binData(i)), 2)
    Next i
    
    CryptBinaryToString = result
End Function

Private Function CryptStringToBinary(ByVal strData As String) As Byte()
    Dim i As Long
    Dim length As Long
    Dim result() As Byte
    
    length = Len(strData) \ 2
    ReDim result(0 To length - 1) As Byte
    
    For i = 0 To length - 1
      result(i) = Val("&H" & Mid(strData, i * 2 + 1, 2))
    Next i
    
    CryptStringToBinary = result
End Function

C#中的AES加密

在C#中，可以使用.NET Framework提供的System.Security.Cryptography命名空间中的类来实现AES加密。下面是一个示例代码：

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

class Program
{
    static void Main()
    {
        string data = "Hello, world!";
        string password = "secretpassword";
        
        byte[] encryptedBytes = AESEncrypt(data, password);
        string encryptedData = Convert.ToBase64String(encryptedBytes);
        
        byte[] decryptedBytes = AESDecrypt(encryptedBytes, password);
        string decryptedData = Encoding.UTF8.GetString(decryptedBytes);
        
        Console.WriteLine($"Encrypted data: {encryptedData}");
        Console.WriteLine($"Decrypted data: {decryptedData}");
    }
    
    static byte[] AESEncrypt(string data, string password)
    {
        byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
        byte[] dataBytes = Encoding.UTF8.GetBytes(data);
        byte[] encryptedBytes;
        
        using (Aes aes = Aes.Create())
        {
            aes.Key = passwordBytes;
            
            using (ICryptoTransform encryptor = aes.CreateEncryptor())
            {
                encryptedBytes = encryptor.TransformFinalBlock(dataBytes, 0, dataBytes.Length);
            }
        }
        
        return encryptedBytes;
    }
    
    static byte[] AESDecrypt(byte[] encryptedBytes, string password)
    {
        byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
        byte[] decryptedBytes;
        
        using (Aes aes = Aes.Create())
        {
            aes.Key = passwordBytes;
            
            using (ICryptoTransform decryptor = aes.CreateDecryptor())
            {
                decryptedBytes = decryptor.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length);
            }
        }
        
        return decryptedBytes;
    }
}

总结

通过上述示例代码，我们可以在VB6和C#中实现AES加密算法。在VB6中，我们使用CryptoAPI来实现加密和解密，而在C#中，我们使用.NET Framework提供的System.Security.Cryptography命名空间。这种加密算法可以在保护敏感数据时提供强大的安全性。