Question

求助!请高手解释一下这段VB代码,谢谢!!!

Function UserCode(password As String) As String
'用户口令加密
Dim il_bit, il_x, il_y, il_z, il_len, i As Long
Dim is_out As String
il_len = Len(password)
il_x = 0
il_y = 0
is_out = ""
For i = 1 To il_len
il_bit = AscW(Mid(password, i, 1)) 'W系列支持unicode

il_y = (il_bit * 13 Mod 256) + il_x
is_out = is_out & ChrW(Fix(il_y)) '取整 int和fix区别: fix修正负数
il_x = il_bit * 13 / 256
Next
is_out = is_out & ChrW(Fix(il_x))

password = is_out
il_len = Len(password)
il_x = 0
il_y = 0
is_out = ""
For i = 1 To il_len
il_bit = AscW(Mid(password, i, 1))
'取前4位值
il_y = il_bit / 16 + 64
is_out = is_out & ChrW(Fix(il_y))
'取后4位值
il_y = (il_bit Mod 16) + 64
is_out = is_out & ChrW(Fix(il_y))
Next
UserCode = is_out
End Function
Function UserDeCode(password As String) As String
'口令解密
Dim is_out As String
Dim il_x, il_y, il_len, i, il_bit As Long

il_len = Len(password)
il_x = 0
il_y = 0
is_out = ""
For i = 1 To il_len Step 2
il_bit = AscW(Mid(password, i, 1))
'取前4位值
il_y = (il_bit - 64) * 16
'取后4位值
'dd = AscW(Mid(password, i + 1, 1)) - 64
il_y = il_y + AscW(Mid(password, i + 1, 1)) - 64
is_out = is_out & ChrW(il_y)
Next

il_x = 0
il_y = 0
password = is_out
is_out = ""

il_len = Len(password)
il_x = AscW(Mid(password, il_len, 1))

For i = (il_len - 1) To 1 Step -1
il_y = il_x * 256 + AscW(Mid(password, i, 1))
il_x = il_y Mod 13
is_out = ChrW(Fix(il_y / 13)) & is_out
Next
UserDeCode = is_out
End Function
il_bit = AscW(Mid(password, i, 1)) 'W系列支持unicode

il_y = (il_bit * 13 Mod 256) + il_x 'Mod是取余数的意思
is_out = is_out & ChrW(Fix(il_y)) '取整 int和fix区别: fix修正负数
il_x = il_bit * 13 / 256
Next '转到for执行下一次循环
is_out = is_out & ChrW(Fix(il_x)) 'chrW是把ASC码转化为字符的函数

password = is_out '赋值
il_len = Len(password) 'il_len的值为参数pwssword的长度
il_x = 0
il_y = 0
is_out = ""
For i = 1 To il_len '又一个循环
il_bit = AscW(Mid(password, i, 1)) 'AscW是把字符转成Asc码,Mid是从字符串中间取一段字符
'取前4位值
il_y = il_bit / 16 + 64
is_out = is_out & ChrW(Fix(il_y))
'取后4位值
il_y = (il_bit Mod 16) + 64
is_out = is_out & ChrW(Fix(il_y))
谢谢高手指点,这一段的算法可以再解释一下吗?

Answer 1

Function UserCode(password As String) As String '自定义函数usercode，包含一个名为password的字符串参数，返回值为字符串
'用户口令加密
Dim il_bit, il_x, il_y, il_z, il_len, i As Long '定义几个变量为整型
Dim is_out As String '定义一个变量为字符串类型
il_len = Len(password) 'il_len=传入的参数password的字符串长度
il_x = 0 '赋值
il_y = 0 '赋值
is_out = "" '赋值
For i = 1 To il_len '用变量i开始从1到il_len的值循环执行以下操作
il_bit = AscW(Mid(password, i, 1)) 'W系列支持unicode

il_y = (il_bit * 13 Mod 256) + il_x 'Mod是取余数的意思
is_out = is_out & ChrW(Fix(il_y)) '取整 int和fix区别: fix修正负数
il_x = il_bit * 13 / 256
Next '转到for执行下一次循环
is_out = is_out & ChrW(Fix(il_x)) 'chrW是把ASC码转化为字符的函数

password = is_out '赋值
il_len = Len(password) 'il_len的值为参数pwssword的长度
il_x = 0
il_y = 0
is_out = ""
For i = 1 To il_len '又一个循环
il_bit = AscW(Mid(password, i, 1)) 'AscW是把字符转成Asc码,Mid是从字符串中间取一段字符
'取前4位值
il_y = il_bit / 16 + 64
is_out = is_out & ChrW(Fix(il_y))
'取后4位值
il_y = (il_bit Mod 16) + 64
is_out = is_out & ChrW(Fix(il_y))
Next '再执行下次循环
UserCode = is_out '函数返回值输出
End Function '自定义函数结束
Function UserDeCode(password As String) As String
'口令解密
Dim is_out As String
Dim il_x, il_y, il_len, i, il_bit As Long

il_len = Len(password)
il_x = 0
il_y = 0
is_out = ""
For i = 1 To il_len Step 2
il_bit = AscW(Mid(password, i, 1))
'取前4位值
il_y = (il_bit - 64) * 16
'取后4位值
'dd = AscW(Mid(password, i + 1, 1)) - 64
il_y = il_y + AscW(Mid(password, i + 1, 1)) - 64
is_out = is_out & ChrW(il_y)
Next

il_x = 0
il_y = 0
password = is_out
is_out = ""

il_len = Len(password)
il_x = AscW(Mid(password, il_len, 1))

For i = (il_len - 1) To 1 Step -1
il_y = il_x * 256 + AscW(Mid(password, i, 1))
il_x = il_y Mod 13
is_out = ChrW(Fix(il_y / 13)) & is_out
Next
UserDeCode = is_out
End Function
'第二个函数是用来对第一个函数加过密的字串进行反算解密的。