Tomass1996's Base64 program with copyright notice at top

--[[
Copyright © 2012 Thomas Farr a.k.a tomass1996 [[email protected]]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
copies of the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

-The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
-Visible credit is given to the original author.
-The software is distributed in a non-profit way.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
]]--
function lsh(value,shift)
    return (value*(2^shift)) % 256
end
function rsh(value,shift)
    return math.floor(value/2^shift) % 256
end
function bit(x,b)
    return (x % 2^b - x % 2^(b-1) > 0)
end
function lor(x,y)
    result = 0
    for p=1,8 do result = result + (((bit(x,p) or bit(y,p)) == true) and 2^(p-1) or 0) end
    return result
end

-- Encoding
local base64chars = {[0]='A',[1]='B',[2]='C',[3]='D',[4]='E',[5]='F',[6]='G',[7]='H',[8]='I',[9]='J',[10]='K',[11]='L',[12]='M',[13]='N',[14]='O',[15]='P',[16]='Q',[17]='R',[18]='S',[19]='T',[20]='U',[21]='V',[22]='W',[23]='X',[24]='Y',[25]='Z',[26]='a',[27]='b',[28]='c',[29]='d',[30]='e',[31]='f',[32]='g',[33]='h',[34]='i',[35]='j',[36]='k',[37]='l',[38]='m',[39]='n',[40]='o',[41]='p',[42]='q',[43]='r',[44]='s',[45]='t',[46]='u',[47]='v',[48]='w',[49]='x',[50]='y',[51]='z',[52]='0',[53]='1',[54]='2',[55]='3',[56]='4',[57]='5',[58]='6',[59]='7',[60]='8',[61]='9',[62]='-',[63]='_'}
function encode(data)
    local bytes = {}
    local result = ""
    for spos=0,string.len(data)-1,3 do
        for byte=1,3 do bytes[byte] = string.byte(string.sub(data,(spos+byte))) or 0 end
        result = string.format('%s%s%s%s%s',result,base64chars[rsh(bytes[1],2)],base64chars[lor(lsh((bytes[1] % 4),4), rsh(bytes[2],4))] or "=",((#data-spos) > 1) and base64chars[lor(lsh(bytes[2] % 16,2), rsh(bytes[3],6))] or "=",((#data-spos) > 2) and base64chars[(bytes[3] % 64)] or "=")
    end
    return result
end

-- Decoding
local base64bytes = {['A']=0,['B']=1,['C']=2,['D']=3,['E']=4,['F']=5,['G']=6,['H']=7,['I']=8,['J']=9,['K']=10,['L']=11,['M']=12,['N']=13,['O']=14,['P']=15,['Q']=16,['R']=17,['S']=18,['T']=19,['U']=20,['V']=21,['W']=22,['X']=23,['Y']=24,['Z']=25,['a']=26,['b']=27,['c']=28,['d']=29,['e']=30,['f']=31,['g']=32,['h']=33,['i']=34,['j']=35,['k']=36,['l']=37,['m']=38,['n']=39,['o']=40,['p']=41,['q']=42,['r']=43,['s']=44,['t']=45,['u']=46,['v']=47,['w']=48,['x']=49,['y']=50,['z']=51,['0']=52,['1']=53,['2']=54,['3']=55,['4']=56,['5']=57,['6']=58,['7']=59,['8']=60,['9']=61,['-']=62,['_']=63,['=']=nil}
function decode(data)
    local chars = {}
    local result=""
    for dpos=0,string.len(data)-1,4 do
        for char=1,4 do chars[char] = base64bytes[(string.sub(data,(dpos+char),(dpos+char)) or "=")] end
        result = string.format('%s%s%s%s',result,string.char(lor(lsh(chars[1],2), rsh(chars[2],4))),(chars[3] ~= nil) and string.char(lor(lsh(chars[2],4), rsh(chars[3],2))) or "",(chars[4] ~= nil) and string.char(lor(lsh(chars[3],6) % 192, (chars[4]))) or "")
    end
    return result
end

tArgs = {...}
EorD = tArgs[1]
ForS = tArgs[2]
tBE = tArgs[3]
if not EorD or not ForS or not tBE then
    error("Usage: Base64 <-E:-D> <-F:-S> <FileName:String>")
end

if EorD == "-E" or EorD == "-e" then
    if ForS == "-F" or ForS == "-f" then
        if fs.exists(tBE) then
            file = io.open(tBE, "r")
            fileCont = file:read("*a")
            file:close()
            encoded = encode(fileCont)
            encfile = io.open(tBE..".b64", "w")
            encfile:write(encoded)
            encfile:close()
            print("Original File: "..tBE.." | Encoded File: "..tBE..".b64")
        else
            error("File "..tBE.." Doesn't Exist")
        end
    elseif ForS == "-S" or ForS == "-s" then
        encoded = encode(tBE)
        print("Original: "..tBE.." | Encoded: "..encoded)
    else
        error("I don't understand: "..ForS)
    end
elseif EorD == "-D" or EorD == "-d" then
    if ForS == "-F" or ForS == "-f" then
        if fs.exists(tBE) then
            file = io.open(tBE, "r")
            fileCont = file:read("*a")
            file:close()
            decoded = decode(fileCont)
            decfile = io.open(tBE..".DECb64", "w")
            decfile:write(decoded)
            decfile:close()
            print("Original File: "..tBE.." | Decoded File: "..tBE..".DECb64")
        else
            error("File "..tBE.." Doesn't Exist")
        end
    elseif ForS == "-S" or ForS == "-s" then
        decoded = decode(tBE)
        print("Original: "..tBE.." | Decoded: "..decoded)
    else
        error("I don't understand: "..ForS)
    end
else
    error("I don't understand: "..EorD)
end