使用md5加密的缺点是不能进行解密，这是一个麻烦事。
现在我想实现的功能是：
给某网站一个地址，这个地址用来展示该网站在公司网站上发布的产品。如果直接使用http://www.aspprogram.cn/a.asp?id=2来的话，客户如果修改2为3后，这个客户就转为其他网站的客户了，那这个网站损失了一个客户，自己的宣传就白宣传了。
所以我想起来对这个2进行加密，以至于客户不可以修改为3。
在网上找了两天，终于找到。
< %
dim sBASE_64_CHARACTERS,varchar,varasc
dim len1
dim i
dim m3
sBASE_64_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
sBASE_64_CHARACTERS = strUnicode2Ansi(sBASE_64_CHARACTERS)
Function strUnicodeLen(asContents)
'计算unicode字符串的Ansi编码的长度
asContents1="a"&asContents
len1=len(asContents1)
k=0
for i=1 to len1
asc1=asc(mid(asContents1,i,1))
if asc1<0 then asc1=65536+asc1
if asc1>255 then
k=k+2
else
k=k+1
end if
next
strUnicodeLen=k-1
End Function
Function strUnicode2Ansi(asContents)
'将Unicode编码的字符串，转换成Ansi编码的字符串
strUnicode2Ansi=""
len1=len(asContents)
for i=1 to len1
varchar=mid(asContents,i,1)
varasc=asc(varchar)
if varasc<0 then varasc=varasc+65536
if varasc>255 then
varHex=Hex(varasc)
varlow=left(varHex,2)
varhigh=right(varHex,2)
strUnicode2Ansi=strUnicode2Ansi & chrb("&H" & varlow ) & chrb("&H" & varhigh )
else
strUnicode2Ansi=strUnicode2Ansi & chrb(varasc)
end if
next
End function
Function strAnsi2Unicode(asContents)
'将Ansi编码的字符串，转换成Unicode编码的字符串
strAnsi2Unicode = ""
len1=lenb(asContents)
if len1=0 then exit function
for i=1 to len1
varchar=midb(asContents,i,1)
varasc=ascb(varchar)
if varasc > 127 then
strAnsi2Unicode = strAnsi2Unicode & chr(ascw(midb(asContents,i+1,1) & varchar))
i=i+1
else
strAnsi2Unicode = strAnsi2Unicode & chr(varasc)
end if
next
End function
Function Base64encode(asContents)
'将Ansi编码的字符串进行Base64编码
'asContents应当是ANSI编码的字符串（二进制的字符串也可以）
Dim lnPosition
Dim lsResult
Dim Char1
Dim Char2
Dim Char3
Dim Char4
Dim Byte1
Dim Byte2
Dim Byte3
Dim SaveBits1
Dim SaveBits2
Dim lsGroupBinary
Dim lsGroup64
Dim m4,len1,len2
len1=Lenb(asContents)
if len1<1 then
Base64encode=""
exit Function
end if
m3=Len1 Mod 3
If M3 > 0 Then asContents = asContents & String(3-M3, chrb(0))
IF m3 > 0 THEN
len1=len1+(3-m3)
len2=len1-3
else
len2=len1
end if
lsResult = ""
For lnPosition = 1 To len2 Step 3
lsGroup64 = ""
lsGroupBinary = Midb(asContents, lnPosition, 3)
Byte1 = Ascb(Midb(lsGroupBinary, 1, 1)): SaveBits1 = Byte1 And 3
Byte2 = Ascb(Midb(lsGroupBinary, 2, 1)): SaveBits2 = Byte2 And 15
Byte3 = Ascb(Midb(lsGroupBinary, 3, 1))
Char1 = Midb(sBASE_64_CHARACTERS, ((Byte1 And 252) \ 4) + 1, 1)
Char2 = Midb(sBASE_64_CHARACTERS, (((Byte2 And 240) \ 16) Or (SaveBits1 * 16) And &HFF) + 1, 1)
Char3 = Midb(sBASE_64_CHARACTERS, (((Byte3 And 192) \ 64) Or (SaveBits2 * 4) And &HFF) + 1, 1)
Char4 = Midb(sBASE_64_CHARACTERS, (Byte3 And 63) + 1, 1)
lsGroup64 = Char1 & Char2 & Char3 & Char4
lsResult = lsResult & lsGroup64
Next
if M3 > 0 then
lsGroup64 = ""
lsGroupBinary = Midb(asContents, len2+1, 3)
Byte1 = Ascb(Midb(lsGroupBinary, 1, 1)): SaveBits1 = Byte1 And 3
Byte2 = Ascb(Midb(lsGroupBinary, 2, 1)): SaveBits2 = Byte2 And 15
Byte3 = Ascb(Midb(lsGroupBinary, 3, 1))
Char1 = Midb(sBASE_64_CHARACTERS, ((Byte1 And 252) \ 4) + 1, 1)
Char2 = Midb(sBASE_64_CHARACTERS, (((Byte2 And 240) \ 16) Or (SaveBits1 * 16) And &HFF) + 1, 1)
Char3 = Midb(sBASE_64_CHARACTERS, (((Byte3 And 192) \ 64) Or (SaveBits2 * 4) And &HFF) + 1, 1)
if M3=1 then
lsGroup64 = Char1 & Char2 & ChrB(61) & ChrB(61)
else
lsGroup64 = Char1 & Char2 & Char3 & ChrB(61)
end if
lsResult = lsResult & lsGroup64
end if
Base64encode = lsResult
End Function
Function Base64decode(asContents)
'将Base64编码字符串转换成Ansi编码的字符串
'asContents应当也是ANSI编码的字符串（二进制的字符串也可以）
Dim lsResult
Dim lnPosition
Dim lsGroup64, lsGroupBinary
Dim Char1, Char2, Char3, Char4
Dim Byte1, Byte2, Byte3
Dim M4,len1,len2
len1= Lenb(asContents)
M4 = len1 Mod 4
if len1 < 1 or M4 > 0 then
Base64decode = ""
exit Function
end if
if midb(asContents, len1, 1) = chrb(61) then m4=3
if midb(asContents, len1-1, 1) = chrb(61) then m4=2
if m4 = 0 then
len2=len1
else
len2=len1-4
end if
For lnPosition = 1 To Len2 Step 4
lsGroupBinary = ""
lsGroup64 = Midb(asContents, lnPosition, 4)
Char1 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 1, 1)) - 1
Char2 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 2, 1)) - 1
Char3 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 3, 1)) - 1
Char4 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 4, 1)) - 1
Byte1 = Chrb(((Char2 And 48) \ 16) Or (Char1 * 4) And &HFF)
Byte2 = lsGroupBinary & Chrb(((Char3 And 60) \ 4) Or (Char2 * 16) And &HFF)
Byte3 = Chrb((((Char3 And 3) * 64) And &HFF) Or (Char4 And 63))
lsGroupBinary = Byte1 & Byte2 & Byte3
lsResult = lsResult & lsGroupBinary
Next
'处理最后剩余的几个字符
if M4 > 0 then
lsGroupBinary = ""
lsGroup64 = Midb(asContents, len2+1, m4) & chrB(65) 'chr(65)=A，转换成值为0
if M4=2 then '补足4位，是为了便于计算
lsGroup64 = lsGroup64 & chrB(65)
end if
Char1 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 1, 1)) - 1
Char2 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 2, 1)) - 1
Char3 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 3, 1)) - 1
Char4 = InStrb(sBASE_64_CHARACTERS, Midb(lsGroup64, 4, 1)) - 1
Byte1 = Chrb(((Char2 And 48) \ 16) Or (Char1 * 4) And &HFF)
Byte2 = lsGroupBinary & Chrb(((Char3 And 60) \ 4) Or (Char2 * 16) And &HFF)
Byte3 = Chrb((((Char3 And 3) * 64) And &HFF) Or (Char4 And 63))
if M4=2 then
lsGroupBinary = Byte1
elseif M4=3 then
lsGroupBinary = Byte1 & Byte2
end if
lsResult = lsResult & lsGroupBinary
end if
Base64decode = lsResult
End Function
'=============================================
Function Encode(passwd)
Encode=strAnsi2Unicode(Base64encode(strUnicode2Ansi(passwd)))
End Function
Function Decode(passwd)
Decode=strAnsi2Unicode(Base64decode(strUnicode2Ansi(passwd)))
End Function
'************************举例开始**************************
key="aspprogram.cn-1"
response.write "key="&key&"<br>"
m=encode(key)
response.write "加密得到："&m&"<br>"
n=decode(m)
response.write "解密得到："&n&"<br>"
'************************举例结束**************************
% >
将上面代码保存为asp文件，运行一下即可