Imports System.IO
Imports System.Security.Cryptography
Imports System.Text

Public Class StringEncryption

    Public Shared KeyBase64 As String = "JVr/l75Wv29+d643g7+h89Q2Z4m/a1bY09iKz8Wn6as="
    Public Shared IVBase64 As String = "n869V+6/7Q11p049/wE99g=="


    ''' <summary>
    ''' 使用 AES 加密字符串。
    ''' </summary>
    ''' <param name="plainText">要加密的明文字符串。</param>
    ''' <param name="key">用于加密的密钥（必须是 AES 密钥大小，例如 128, 192 或 256 位）。</param>
    ''' <param name="iv">初始化向量（IV），用于增加加密的随机性（必须是 AES 块大小，即 16 字节）。</param>
    ''' <returns>Base64 编码的密文字符串。</returns>
    Public Shared Function EncryptStringAES(plainText As String, KeyBase64 As String, IVBase64 As String) As String
        Dim Key As Byte()
        Dim iv As Byte()
        Try
            Key = System.Convert.FromBase64String(KeyBase64)
            iv = System.Convert.FromBase64String(IVBase64)
        Catch ex As Exception
            Console.WriteLine("密钥和向量失败 err:", ex.Message)
        End Try
        ' 检查输入是否有效
        If plainText Is Nothing OrElse plainText.Length <= 0 Then
            Throw New ArgumentNullException("plainText")
        End If
        If Key Is Nothing OrElse Key.Length <= 0 Then
            Throw New ArgumentNullException("key")
        End If
        If iv Is Nothing OrElse iv.Length <= 0 Then
            Throw New ArgumentNullException("iv")
        End If
        If Key.Length <> 16 AndAlso Key.Length <> 24 AndAlso Key.Length <> 32 Then
            Throw New ArgumentException("密钥长度必须为 128, 192 或 256 位 (16, 24 或 32 字节)。")
        End If
        If iv.Length <> 16 Then
            Throw New ArgumentException("IV 长度必须为 128 位 (16 字节)。")
        End If

        Dim encrypted As Byte()

        ' 使用 AES 加密
        Using aesAlg As Aes = Aes.Create()
            aesAlg.Key = Key
            aesAlg.IV = iv

            ' 创建加密器
            Dim encryptor As ICryptoTransform = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV)

            ' 使用内存流进行加密
            Using msEncrypt As New MemoryStream()
                Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
                    Using swEncrypt As New StreamWriter(csEncrypt)
                        ' 将所有数据写入流。
                        swEncrypt.Write(plainText)
                    End Using
                    encrypted = msEncrypt.ToArray()
                End Using
            End Using
        End Using

        ' 返回 Base64 编码的加密字节
        Return Convert.ToBase64String(encrypted)
    End Function

    ''' <summary>
    ''' 使用 AES 解密字符串。
    ''' </summary>
    ''' <param name="cipherText">要解密的 Base64 编码的密文字符串。</param>
    ''' <param name="key">用于解密的密钥（必须与加密时使用的密钥相同）。</param>
    ''' <param name="iv">用于解密的初始化向量（必须与加密时使用的 IV 相同）。</param>
    ''' <returns>解密后的明文字符串。</returns>
    Public Shared Function DecryptStringAES(cipherText As String, keyBase As String, ivBase As String) As String
        Dim key As Byte()
        Dim iv As Byte()

        Try
            key = Convert.FromBase64String(KeyBase64)
            iv = Convert.FromBase64String(IVBase64)
        Catch ex As Exception
            Console.WriteLine("密钥和向量失败 err:", ex.Message)
        End Try

        ' 检查输入是否有效
        If cipherText Is Nothing OrElse cipherText.Length <= 0 Then
            Throw New ArgumentNullException("cipherText")
        End If
        If key Is Nothing OrElse key.Length <= 0 Then
            Throw New ArgumentNullException("key")
        End If
        If iv Is Nothing OrElse iv.Length <= 0 Then
            Throw New ArgumentNullException("iv")
        End If
        If key.Length <> 16 AndAlso key.Length <> 24 AndAlso key.Length <> 32 Then
            Throw New ArgumentException("密钥长度必须为 128, 192 或 256 位 (16, 24 或 32 字节)。")
        End If
        If iv.Length <> 16 Then
            Throw New ArgumentException("IV 长度必须为 128 位 (16 字节)。")
        End If

        ' 将 Base64 编码的密文转换为字节数组
        Dim encryptedBytes As Byte() = Convert.FromBase64String(cipherText)

        ' 用于存储解密后的明文
        Dim plaintext As String = String.Empty

        ' 使用 AES 解密
        Using aesAlg As Aes = Aes.Create()
            aesAlg.Key = key
            aesAlg.IV = iv

            ' 创建解密器
            Dim decryptor As ICryptoTransform = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV)

            ' 使用内存流进行解密
            Using msDecrypt As New MemoryStream(encryptedBytes)
                Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)
                    Using srDecrypt As New StreamReader(csDecrypt)
                        ' 从解密流中读取所有字节并将其解码为字符串。
                        plaintext = srDecrypt.ReadToEnd()
                    End Using
                End Using
            End Using
        End Using

        Return plaintext
    End Function

    ''' <summary>
    ''' 生成一个随机的 AES 密钥。
    ''' </summary>
    ''' <param name="keySize">所需的密钥大小（以位为单位，例如 128, 192 或 256）。</param>
    ''' <returns>随机生成的密钥字节数组。</returns>
    Public Shared Function GenerateRandomKey(keySize As Integer) As Byte()
        Using aesAlg As Aes = Aes.Create()
            aesAlg.KeySize = keySize
            aesAlg.GenerateKey()
            Return aesAlg.Key
        End Using
    End Function

    ''' <summary>
    ''' 生成一个随机的 AES 初始化向量 (IV)。
    ''' </summary>
    ''' <returns>随机生成的 IV 字节数组。</returns>
    Public Shared Function GenerateRandomIV() As Byte()
        Using aesAlg As Aes = Aes.Create()
            aesAlg.GenerateIV()
            Return aesAlg.IV
        End Using
    End Function

End Class