使用md5加密的缺點是不能進行解密，這是一個麻煩事。
現在我想實現的功能是：
給某網站一個地址，這個地址用來展示該網站在公司網站上發布的產品。如果直接使用http://www.aspprogram.cn/a.ASP?id=2來的話，客戶如果修改2為3後，這個客戶就轉為其他網站的客戶了，那這個網站損失了一個客戶，自己的宣傳就白宣傳了。
所以我想起來對這個2進行加密，以至於客戶不可以修改為3。
在網上找了兩天，終於找到。
< %
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)
'計算unicode字符串的Ansi編碼的長度
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)
'將Unicode編碼的字符串，轉換成Ansi編碼的字符串
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)
'將Ansi編碼的字符串，轉換成Unicode編碼的字符串
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)
'將Ansi編碼的字符串進行Base64編碼
'asContents應當是ANSI編碼的字符串（二進制的字符串也可以）
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)
'將Base64編碼字符串轉換成Ansi編碼的字符串
'asContents應當也是ANSI編碼的字符串（二進制的字符串也可以）
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
'處理最後剩余的幾個字符
if M4 > 0 then
lsGroupBinary = ""
lsGroup64 = Midb(asContents, len2+1, m4) & chrB(65) 'chr(65)=A，轉換成值為0
if M4=2 then '補足4位，是為了便於計算
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
'************************舉例開始**************************
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>"
'************************舉例結束**************************
% >
將上面代碼保存為ASP文件，運行一下即可
