VB.Net 字符串加密类

Public Class Cls_JM


    ‘使用
    ‘Dim Jm As New Cls_JM(2)
    ‘Dim strTmp As String

    ‘Jm.jiemi(strTmp)
    ‘Jm.Jiami(strTmp)

    Private TripleDes As New System.Security.Cryptography.TripleDESCryptoServiceProvider

    Private Function TruncateHash(ByVal key As String, ByVal length As Integer) As Byte()
        Dim sha1 As New System.Security.Cryptography.SHA1CryptoServiceProvider  ‘ Hash the key.  
        Dim keyBytes() As Byte = System.Text.Encoding.Unicode.GetBytes(key)
        Dim hash() As Byte = sha1.ComputeHash(keyBytes)  ‘ Truncate or pad the hash. 
        ReDim Preserve hash(length - 1)
        Return hash
    End Function

    Sub New(ByVal key As String)  ‘ Initialize the crypto provider.  
        TripleDes.Key = TruncateHash(key, TripleDes.KeySize \ 8)
        TripleDes.IV = TruncateHash("", TripleDes.BlockSize \ 8)
    End Sub

    Public Function jiami(ByVal plaintext As String) As String  ‘ Convert the plaintext string to a byte array. 
        Dim plaintextBytes() As Byte = System.Text.Encoding.Unicode.GetBytes(plaintext)  ‘ Create the stream. 
        Dim ms As New System.IO.MemoryStream  ‘ Create the encoder to write to the stream. 
        Dim encStream As New System.Security.Cryptography.CryptoStream(ms, TripleDes.CreateEncryptor(), System.Security.Cryptography.CryptoStreamMode.Write)  ‘ Use the crypto stream to write the byte array to the stream. 
        encStream.Write(plaintextBytes, 0, plaintextBytes.Length)
        encStream.FlushFinalBlock()  ‘ Convert the encrypted stream to a printable string. 
        Return Convert.ToBase64String(ms.ToArray)
    End Function

    Public Function jiemi(ByVal encryptedtext As String) As String  ‘ Convert the encrypted text string to a byte array. 
        Dim encryptedBytes() As Byte = Convert.FromBase64String(encryptedtext)  ‘ Create the stream. 
        Dim ms As New System.IO.MemoryStream  ‘ Create the decoder to write to the stream. 
        Dim decStream As New System.Security.Cryptography.CryptoStream(ms, TripleDes.CreateDecryptor(), System.Security.Cryptography.CryptoStreamMode.Write)  ‘ Use the crypto stream to write the byte array to the stream. 
        decStream.Write(encryptedBytes, 0, encryptedBytes.Length)
        decStream.FlushFinalBlock()  ‘ Convert the plaintext stream to a string. 
        Return System.Text.Encoding.Unicode.GetString(ms.ToArray)
    End Function


End Class