local base64 = {} local extract = bit32 and bit32.extract if not extract then if bit then local shl, shr, band = bit.lshift, bit.rshift, bit.band extract = function( v, from, width ) return band( shr( v, from ), shl( 1, width ) - 1 ) end elseif _G._VERSION >= "Lua 5.3" then extract = load[[return function( v, from, width ) return ( v >> from ) & ((1 << width) - 1) end]]() else extract = function( v, from, width ) local w = 0 local flag = 2^from for i = 0, width-1 do local flag2 = flag + flag if v % flag2 >= flag then w = w + 2^i end flag = flag2 end return w end end end local char, concat = string.char, table.concat function base64.makeencoder( s62, s63, spad ) local encoder = {} for b64code, char in pairs{[0]='A','B','C','D','E','F','G','H','I','J', 'K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y', 'Z','a','b','c','d','e','f','g','h','i','j','k','l','m','n', 'o','p','q','r','s','t','u','v','w','x','y','z','0','1','2', '3','4','5','6','7','8','9',s62 or '+',s63 or'/',spad or'='} do encoder[b64code] = char:byte() end return encoder end function base64.makedecoder( s62, s63, spad ) local decoder = {} for b64code, charcode in pairs( base64.makeencoder(s64,s63,spad)) do decoder[charcode] = b64code end return decoder end local DEFAULT_ENCODER = base64.makeencoder() local DEFAULT_DECODER = base64.makedecoder() function base64.encode( str, encoder, usecaching ) encoder = encoder or DEFAULT_ENCODER local t, k, n = {}, 1, #str local lastn = n % 3 local cache = {} for i = 1, n-lastn, 3 do local a, b, c = str:byte( i, i+2 ) local v = a*0x10000 + b*0x100 + c local s if usecaching then s = cache[v] if not s then s = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[extract(v,0,6)]) cache[v] = s end else s = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[extract(v,0,6)]) end t[k] = s k = k + 1 end if lastn == 2 then local a, b = str:byte( n-1, n ) local v = a*0x10000 + b*0x100 t[k] = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[64]) elseif lastn == 1 then local v = str:byte( n )*0x10000 t[k] = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[64], encoder[64]) end return concat( t ) end function base64.decode( b64, decoder, usecaching ) decoder = decoder or DEFAULT_DECODER local cache = usecaching and {} local t, k = {}, 1 local n = #b64 local padding = b64:sub(-2) == '==' and 2 or b64:sub(-1) == '=' and 1 or 0 for i = 1, padding > 0 and n-4 or n, 4 do local a, b, c, d = b64:byte( i, i+3 ) local s if usecaching then local v0 = a*0x1000000 + b*0x10000 + c*0x100 + d s = cache[v0] if not s then local v = decoder[a]*0x40000 + decoder[b]*0x1000 + decoder[c]*0x40 + decoder[d] s = char( extract(v,16,8), extract(v,8,8), extract(v,0,8)) cache[v0] = s end else local v = decoder[a]*0x40000 + decoder[b]*0x1000 + decoder[c]*0x40 + decoder[d] s = char( extract(v,16,8), extract(v,8,8), extract(v,0,8)) end t[k] = s k = k + 1 end if padding == 1 then local a, b, c = b64:byte( n-3, n-1 ) local v = decoder[a]*0x40000 + decoder[b]*0x1000 + decoder[c]*0x40 t[k] = char( extract(v,16,8), extract(v,8,8)) elseif padding == 2 then local a, b = b64:byte( n-3, n-2 ) local v = decoder[a]*0x40000 + decoder[b]*0x1000 t[k] = char( extract(v,16,8)) end return concat( t ) end return base64