AutoHotkey Community

   Locked := true
   Gui, Add, Edit,w250  +Center vKey
   Gui, Add, Button,w250  +Center , Unlock
   Gui, Show, Center,

ButtonUnlock:
GuiControlGet, Key
SubmitedKeyDecoded := InvBase64(Key)
SubmitedEncoded:= Base64(Key)
MsgBox, %SubmitedKeyDecoded %
MsgBox, %SubmitedEncoded%
return

StringCaseSense On
Chars = ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/

Gui Add, Edit, w250 vKey
Gui Add, Button, w120, Encode
Gui Add, Button, w120 xp+130, Decode
Gui Show, Center
Return

ButtonClose:
ButtonEscape:
ExitApp

ButtonEncode:
  GuiControlGet Key
  GuiControl,,Key, % Base64(Key)
return

ButtonDecode:
  GuiControlGet Key
  GuiControl,,Key, % InvBase64(Key)
return

Base64(string) {
   Loop Parse, string
   {
      If Mod(A_Index,3) = 1
         buffer := Asc(A_LoopField) << 16
      Else If Mod(A_Index,3) = 2
         buffer += Asc(A_LoopField) << 8
      Else {
         buffer += Asc(A_LoopField)
         out := out . Code(buffer>>18) . Code(buffer>>12) . Code(buffer>>6) . Code(buffer)
      }
   }
   If Mod(StrLen(string),3) = 0
      Return out
   If Mod(StrLen(string),3) = 1
      Return out . Code(buffer>>18) . Code(buffer>>12) "=="
   Return out . Code(buffer>>18) . Code(buffer>>12) . Code(buffer>>6) "="
}

InvBase64(code) {
   StringReplace code, code, =,,All
   Loop Parse, code
   {
      If Mod(A_Index,4) = 1
         buffer := DeCode(A_LoopField) << 18
      Else If Mod(A_Index,4) = 2
         buffer += DeCode(A_LoopField) << 12
      Else If Mod(A_Index,4) = 3
         buffer += DeCode(A_LoopField) << 6
      Else {
         buffer += DeCode(A_LoopField)
         out := out . Chr(buffer>>16) . Chr(255 & buffer>>8) . Chr(255 & buffer)
      }
   }
   If Mod(StrLen(code),4) = 0
      Return out
   If Mod(StrLen(code),4) = 2
      Return out . Chr(buffer>>16)
   Return out . Chr(buffer>>16) . Chr(255 & buffer>>8)
}

Code(i) {   ; <== Chars[i & 63], 0-base index
   Global Chars
   StringMid i, Chars, (i&63)+1, 1
   Return i
}

DeCode(c) { ; c = a char in Chars ==> position [0,63]
   Global Chars
   Return InStr(Chars,c,1) - 1
}

;;;;; ----- Binary to base64/formatted-HEX conversion by the Crypto API, for XP+  (2HEX, 2Base64)
; http://msdn.microsoft.com/en-us/library/aa380285(VS.85).aspx
; http://www.autohotkey.com/forum/viewtopic.php?p=238120#238120

; fmt = 1:base64, 4:hex-table, 5:hex+ASCII, 10:offs+hex, 11:offs+hex+ASCII, 12:raw-hex

BinaryToString(ByRef bin, sz=0, fmt=12) {   ; return base64 or formatted-hex
   n := sz>0 ? sz : VarSetCapacity(bin)
   DllCall("Crypt32.dll\CryptBinaryToStringA", UInt,&bin, UInt,n, UInt,fmt, UInt,0, UIntP,cp, "CDECL UInt") ; get size
   VarSetCapacity(str,cp)
   DllCall("Crypt32.dll\CryptBinaryToStringA", UInt,&bin, UInt,n, UInt,fmt, UInt,&str, UIntP,cp, "CDECL UInt")
   Return str
}

StringToBinary(ByRef bin, hex, fmt=12) {    ; return length, result in bin
   DllCall("Crypt32.dll\CryptStringToBinaryA", UInt,&hex, UInt,StrLen(hex), UInt,fmt, UInt,0, UIntP,cp, UInt,0,UInt,0,"CDECL UInt") ; get size
   VarSetCapacity(bin,cp)
   DllCall("Crypt32.dll\CryptStringToBinaryA", UInt,&hex, UInt,StrLen(hex), UInt,fmt, UInt,&bin, UIntP,cp, UInt,0,UInt,0,"CDECL UInt")
   Return cp
}
                                            ; TEST
VarSetCapacity(bin,100,122)                 ; 100 z-chars
fmt = 11                                    ; table: offs+hex+ASCII
MsgBox % hex:= BinaryToString(bin,100,fmt)  ; encode

len := StringToBinary(bin1,hex,fmt)         ; decode
VarSetCapacity(bin1,-1)                     ; use only with string in bin1
bin1 := SubStr(bin1,1,len)                  ; strip of garbage at the end
MsgBox %len%: %bin1%                        ; show len, original data

   VarSetCapacity(bin, 3*StrLen(code)//4, 0)
   StringReplace code, code, =,,All

   StringReplace code, code, =,,All
   VarSetCapacity(bin, 3*StrLen(code)//4, 0)

Base64Decode(ByRef bin, code) {
   StringReplace code, code, =,,All
   decodedbytes := 3*StrLen(code)//4
   VarSetCapacity(bin, decodedbytes, 0)
   ...
   return decodedbytes
}