asp base 64 복호화 함수 코드

<% 

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

Function strUnicodeLen(asContents) 
'  unicode    Ansi      
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) 
' Unicode      ，   Ansi       
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) 
' Ansi      ，   Unicode       
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) 
' Ansi        Base64   
'asContents   ANSI      （          ） 
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) 
' Base64        Ansi       
'asContents    ANSI      （          ） 
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 
'        4    
Base64decode = "" 
exit Function 
end if 

'          =   
'           =   
'  m4                   
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 

'            
if M4 > 0 then 
lsGroupBinary = "" 
lsGroup64 = Midb(asContents, len2+1, m4) & chrB(65) 'chr(65)=A，     0 
if M4=2 then '  4 ，        
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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