<% 

sBASE_64_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" 
sBASE_64_CHARACTERS = strUnicode2Ansi(sBASE_64_CHARACTERS) 

Function strUnicodeLen(asContents) 
'計(jì)算unicode字符串的Ansi編碼的長(zhǎng)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(zhuǎn)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(zhuǎn)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(jìn)行Base64編碼 
'asContents應(yīng)當(dāng)是ANSI編碼的字符串（二進(jìn)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)) 
'補(bǔ)足位數(shù)是為了便于計(jì)算 

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 

'處理最后剩余的幾個(gè)字符 
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) '用=號(hào)補(bǔ)足位數(shù) 
else 
lsGroup64 = Char1 & Char2 & Char3 & ChrB(61) '用=號(hào)補(bǔ)足位數(shù) 
end if 

lsResult = lsResult & lsGroup64 
end if 

Base64encode = lsResult 

End Function 


Function Base64decode(asContents) 
'將Base64編碼字符串轉(zhuǎn)換成Ansi編碼的字符串 
'asContents應(yīng)當(dāng)也是ANSI編碼的字符串（二進(jìn)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 
'字符串長(zhǎng)度應(yīng)當(dāng)是4的倍數(shù) 
Base64decode = "" 
exit Function 
end if 

'判斷最后一位是不是 = 號(hào) 
'判斷倒數(shù)第二位是不是 = 號(hào) 
'這里m4表示最后剩余的需要單獨(dú)處理的字符個(gè)數(shù) 
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 

'處理最后剩余的幾個(gè)字符 
if M4 > 0 then 
lsGroupBinary = "" 
lsGroup64 = Midb(asContents, len2+1, m4) & chrB(65) 'chr(65)=A，轉(zhuǎn)換成值為0 
if M4=2 then '補(bǔ)足4位，是為了便于計(jì)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 
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