classencrypttext.vb

vb.net编写的数据加密程序

#Region "信息加密和解密"

Public Class EncryptText

#Region "Function HandleChar() —— 字符运算处理"
    Public Function HandleChar(ByVal SourceChar As Integer, ByVal EChar As Char) As Integer
        Dim tempchar
        tempchar = SourceChar
        tempchar = tempchar Xor Asc(EChar)
        Return tempchar
    End Function
#End Region

#Region "Function EncryptString() —— 字符串加密"
    Public Function EncryptString(ByVal sourcestr As String, ByVal EStr As String) As String
        If EStr = "" Then
            EStr = "lipeng@cs-air"  '密钥Estr的默认值
        End If

        Dim si, ei As Integer
        Dim Stempchar, result As String
        Dim tempresult As Integer
        Dim Etempchar As String

        si = 1
        Stempchar = Left(sourcestr, 1)
        result = ""
        Do While Not Stempchar = ""  '依次加密明文字符

            ei = 1
            Etempchar = Left(EStr, 1)  '选取密钥的第一个字符
            tempresult = Asc(Stempchar)
            Do While Not Etempchar = ""  '依次选取密钥与明文字符运算
                tempresult = HandleChar(tempresult, Etempchar)
                Etempchar = Left(Right(EStr, Len(EStr) - ei), 1)
                ei = ei + 1     '选取下一个密钥字符
            Loop
            If result <> "" Then
                result = result + "-" + Trim(tempresult) '密文数据以 '－' 相连
            Else
                result = result + Trim(tempresult)
            End If

            '取下一个明文字符
            Stempchar = Left(Right(sourcestr, Len(sourcestr) - si), 1)
            si = si + 1
        Loop

        Return result
    End Function
#End Region

#Region "Function DecryptString() —— 字符串解密"
    Public Function DecryptString(ByVal sourcestr As String, ByVal DStr As String) As String
        If DStr = "" Then
            DStr = "lipeng@cs-air"
        End If

        If Trim(sourcestr) = "" Then Return ""

        Dim si, di As Integer
        Dim Stempchar, result As String
        Dim Dtempchar As String
        Dim tempresult As Integer

        Dim sstrarr() As String
        Dim arrcount, arri As Integer

        sstrarr = Split(sourcestr, "-")
        arrcount = UBound(sstrarr)

        result = ""

        For si = 0 To arrcount
            tempresult = sstrarr(si)
            di = 1
            Dtempchar = Right(DStr, 1)
            Do While Not Dtempchar = ""
                tempresult = HandleChar(tempresult, Dtempchar)
                Dtempchar = Right(Left(DStr, Len(DStr) - di), 1)
                di = di + 1
            Loop
            result = result + Chr(tempresult)

        Next
        Return result

    End Function
#End Region

#Region "Function ImprovedEncryptString() —— 改进的字符串加密"
    Public Function ImprovedEncryptString(ByVal sourcestr As String, ByVal EStr As String) As String
        If EStr = "" Then
            EStr = "lipeng@cs-air"
        End If

        Dim si, ei, Estrlen As Integer
        Dim Stempchar, result As String
        Dim tempresult As Integer
        Dim Etempchar As String
        Dim EcharArr() As Char

        Estrlen = EStr.Length
        ReDim EcharArr(Estrlen)
        EcharArr = EStr     '将密钥字符串赋给字符数组

        si = 1
        ei = 0
        Stempchar = Left(sourcestr, 1)
        result = ""
        Do While Not Stempchar = ""

            tempresult = Asc(Stempchar)
            Etempchar = EcharArr(ei)

            tempresult = HandleChar(tempresult, Etempchar)

            ei = ei + 1     '选取下一个密钥
            ei = ei Mod Estrlen     '当密钥字符选取完后就从头开始

            If result <> "" Then
                result = result + "-" + Trim(tempresult) '密文数据以 '－' 相连
            Else
                result = result + Trim(tempresult)
            End If

            '取下一个明文字符
            Stempchar = Left(Right(sourcestr, Len(sourcestr) - si), 1)
            si = si + 1
        Loop

        Return result
    End Function
#End Region

#Region "Function ImprovedDecryptString() —— 改进的字符串解密"
    Public Function ImprovedDecryptString(ByVal sourcestr As String, ByVal DStr As String) As String
        If DStr = "" Then
            DStr = "lipeng@cs-air"
        End If

        If Trim(sourcestr) = "" Then Return ""

        Dim si, di, Dstrlen As Integer
        Dim Stempchar, result As String
        Dim Dtempchar As String
        Dim tempresult As Integer

        Dim DcharArr() As Char

        Dstrlen = DStr.Length
        ReDim DcharArr(Dstrlen)
        DcharArr = DStr

        Dim sstrarr() As String
        Dim arrcount, arri As Integer

        sstrarr = Split(sourcestr, "-")
        arrcount = UBound(sstrarr)

        result = ""

        di = 0
        For si = 0 To arrcount
            tempresult = sstrarr(si)

            Dtempchar = DcharArr(di)

            tempresult = HandleChar(tempresult, Dtempchar)

            di = di + 1
            di = di Mod Dstrlen

            result = result + Chr(tempresult)

        Next
        Return result

    End Function
#End Region

End Class

#End Region