Module:Base64: Difference between revisions
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local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/' -- You will need this for encoding/decoding |
local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/' -- You will need this for encoding/decoding |
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--[[**************************************************************************]] |
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-- base64.lua |
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-- Copyright 2014 Ernest R. Ewert |
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-- |
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-- This Lua module contains the implementation of a Lua base64 encode |
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-- and decode library. |
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-- |
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-- The library exposes these methods. |
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-- |
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-- Method Args |
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-- ----------- ---------------------------------------------- |
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-- encode String in / out |
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-- decode String in / out |
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-- |
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-- encode String, function(value) predicate |
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-- decode String, function(value) predicate |
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-- |
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-- encode file, function(value) predicate |
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-- deocde file, function(value) predicate |
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-- |
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-- encode file, file |
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-- deocde file, file |
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-- |
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-- alpha alphabet, term char |
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-- |
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-------------------------------------------------------------------------------- |
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-- known_base64_alphabets |
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-- |
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-- |
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local known_base64_alphabets= |
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{ |
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base64= -- RFC 2045 (Ignores max line length restrictions) |
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{ |
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_alpha="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/", |
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_strip="[^%a%d%+%/%=]", |
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_term="=" |
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}, |
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base64noterm= -- RFC 2045 (Ignores max line length restrictions) |
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{ |
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_alpha="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/", |
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_strip="[^%a%d%+%/]", |
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_term="" |
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}, |
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base64url= -- RFC 4648 'base64url' |
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{ |
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_alpha="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_", |
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_strip="[^%a%d%+%-%_=]", |
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_term="" |
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}, |
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} |
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local c_alpha=known_base64_alphabets.base64 |
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local pattern_strip |
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--[[**************************************************************************]] |
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--[[****************************** Encoding **********************************]] |
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--[[**************************************************************************]] |
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-- Precomputed tables (compromise using more memory for speed) |
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local b64e -- 6 bit patterns to ANSI 'char' values |
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local b64e_a -- ready to use |
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local b64e_a2 -- byte addend |
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local b64e_b1 -- byte addend |
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local b64e_b2 -- byte addend |
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local b64e_c1 -- byte addend |
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local b64e_c -- ready to use |
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-- Tail padding values |
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local tail_padd64= |
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{ |
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"==", -- two bytes modulo |
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"=" -- one byte modulo |
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} |
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-------------------------------------------------------------------------------- |
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-- e64 |
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-- |
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-- Helper function to convert three eight bit values into four encoded |
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-- 6 (significant) bit values. |
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-- |
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-- 7 0 7 0 7 0 |
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-- e64(a a a a a a a a,b b b b b b b b,c c c c c c c c) |
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-- | | | | |
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-- return [ a a a a a a]| | | |
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-- [ a a b b b b]| | |
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-- [ b b b b c c]| |
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-- [ c c c c c c] |
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-- |
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local function e64( a, b, c ) |
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-- Return pre-calculated values for encoded value 1 and 4 |
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-- Get the pre-calculated extractions for value 2 and 3, look them |
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-- up and return the proper value. |
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-- |
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return b64e_a[a], |
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b64e[ b64e_a2[a]+b64e_b1[b] ], |
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b64e[ b64e_b2[b]+b64e_c1[c] ], |
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b64e_c[c] |
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end |
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-------------------------------------------------------------------------------- |
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-- encode_tail64 |
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-- |
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-- Send a tail pad value to the output predicate provided. |
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-- |
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local function encode_tail64( out, x, y ) |
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-- If we have a number of input bytes that isn't exactly divisible |
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-- by 3 then we need to pad the tail |
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if x ~= nil then |
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local a,b,r = x,0,1 |
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if y ~= nil then |
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r = 2 |
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b = y |
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end |
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-- Encode three bytes of info, with the tail byte as zeros and |
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-- ignore any fourth encoded ASCII value. (We should NOT have a |
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-- forth byte at this point.) |
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local b1, b2, b3 = e64( a, b, 0 ) |
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-- always add the first 2 six bit values to the res table |
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-- 1 remainder input byte needs 8 output bits |
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local tail_value = string.char( b1, b2 ) |
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-- two remainder input bytes will need 18 output bits (2 as pad) |
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if r == 2 then |
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tail_value=tail_value..string.char( b3 ) |
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end |
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-- send the last 4 byte sequence with appropriate tail padding |
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out( tail_value .. tail_padd64[r] ) |
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end |
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end |
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-------------------------------------------------------------------------------- |
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-- encode64_io_iterator |
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-- |
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-- Create an io input iterator to read an input file and split values for |
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-- proper encoding. |
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-- |
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local function encode64_io_iterator(file) |
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assert( io.type(file) == "file", "argument must be readable file handle" ) |
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assert( file.read ~= nil, "argument must be readable file handle" ) |
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local ii = { } -- Table for the input iterator |
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setmetatable(ii,{ __tostring=function() return "base64.io_iterator" end}) |
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-- Begin returns an input read iterator |
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-- |
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function ii.begin() |
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local sb = string.byte |
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-- The iterator returns three bytes from the file for encoding or nil |
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-- when the end of the file has been reached. |
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-- |
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return function() |
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s = file:read(3) |
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if s ~= nil and #s == 3 then |
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return sb(s,1,3) |
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end |
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return nil |
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end |
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end |
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-- The tail method on the iterator allows the routines to run faster |
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-- because each sequence of bytes doesn't have to test for EOF. |
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-- |
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function ii.tail() |
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-- If one or two "overflow" bytes exist, return those. |
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-- |
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if s ~= nil then return s:byte(1,2) end |
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end |
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return ii |
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end |
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-------------------------------------------------------------------------------- |
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-- encode64_with_ii |
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-- |
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-- Convert the value provided by an encode iterator that provides a begin |
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-- method, a tail method, and an iterator that returns three bytes for |
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-- each call until at the end. The tail method should return either 1 or 2 |
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-- tail bytes (for source values that are not evenly divisible by three). |
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-- |
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local function encode64_with_ii( ii, out ) |
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local sc=string.char |
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for a, b, c in ii.begin() do |
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out( sc( e64( a, b, c ) ) ) |
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end |
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encode_tail64( out, ii.tail() ) |
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end |
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-------------------------------------------------------------------------------- |
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-- encode64_with_predicate |
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-- |
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-- Implements the basic raw data --> base64 conversion. Each three byte |
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-- sequence in the input string is converted to the encoded string and |
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-- given to the predicate provided in 4 output byte chunks. This method |
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-- is slightly faster for traversing existing strings in memory. |
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-- |
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local function encode64_with_predicate( raw, out ) |
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local rem=#raw%3 -- remainder |
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local len=#raw-rem -- 3 byte input adjusted |
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local sb=string.byte -- Mostly notational (slight performance) |
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local sc=string.char -- Mostly notational (slight performance) |
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-- Main encode loop converts three input bytes to 4 base64 encoded |
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-- ACSII values and calls the predicate with the value. |
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for i=1,len,3 do |
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-- This really isn't intended as obfuscation. It is more about |
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-- loop optimization and removing temporaries. |
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-- |
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out( sc( e64( sb( raw ,i , i+3 ) ) ) ) |
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-- | | | |
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-- | | byte i to i + 3 |
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-- | | |
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-- | returns 4 encoded values |
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-- | |
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-- creates a string with the 4 returned values |
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end |
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-- If we have a number of input bytes that isn't exactly divisible |
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-- by 3 then we need to pad the tail |
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if rem > 0 then |
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local x, y = sb( raw, len+1 ) |
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if rem > 1 then |
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y = sb( raw, len+2 ) |
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end |
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encode_tail64( out, x, y ) |
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end |
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end |
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-------------------------------------------------------------------------------- |
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-- encode64_tostring |
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-- |
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-- Convenience method that accepts a string value and returns the |
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-- encoded version of that string. |
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-- |
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local function encode64_tostring(raw) |
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local sb={} -- table to build string |
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local function collection_predicate(v) |
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sb[#sb+1]=v |
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end |
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-- Test with an 818K string in memory. Result is 1.1M of data. |
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-- |
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-- lua_base64 base64 (gnu 8.21) |
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-- 202ms 54ms |
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-- 203ms 48ms |
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-- 204ms 50ms |
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-- 203ms 42ms |
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-- 205ms 46ms |
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-- |
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encode64_with_predicate( raw, collection_predicate ) |
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return table.concat(sb) |
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end |
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--[[**************************************************************************]] |
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--[[****************************** Decoding **********************************]] |
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--[[**************************************************************************]] |
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-- Precomputed tables (compromise using more memory for speed) |
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local b64d -- ANSI 'char' to right shifted bit pattern |
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local b64d_a1 -- byte addend |
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local b64d_a2 -- byte addend |
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local b64d_b1 -- byte addend |
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local b64d_b2 -- byte addend |
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local b64d_c1 -- byte addend |
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local b64d_z -- zero |
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-------------------------------------------------------------------------------- |
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-- d64 |
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-- |
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-- Helper function to convert four six bit values into three full eight |
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-- bit values. Input values are the integer expression of the six bit value |
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-- encoded in the original base64 encoded string. |
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-- |
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-- d64( _ _1 1 1 1 1 1, |
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-- | _ _ 2 2 2 2 2 2, |
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-- | | _ _ 3 3 3 3 3 3, |
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-- | | | _ _ 4 4 4 4 4 4) |
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-- | | | | |
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-- return ', [1 1 1 1 1 1 2 2] | | |
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-- ', [2 2 2 2 3 3 3 3] | |
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-- ' [3 3 4 4 4 4 4 4] |
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-- |
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local function d64( b1, b2, b3, b4 ) |
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-- We can get away with addition instead of anding the values together |
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-- because there are no overlapping bit patterns. |
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-- |
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return |
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b64d_a1[b1] + b64d_a2[b2], |
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b64d_b1[b2] + b64d_b2[b3], |
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b64d_c1[b3] + b64d[b4] |
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end |
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-------------------------------------------------------------------------------- |
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-- decode_tail64 |
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-- |
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-- Send the end of stream bytes that didn't get decoded via the main loop. |
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-- |
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local function decode_tail64( out, e1, e2 ,e3, e4 ) |
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if tail_padd64[2] == "" or e4 == tail_padd64[2]:byte() then |
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local n3 = b64d_z |
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if e3 ~= nil and e3 ~= tail_padd64[2]:byte() then |
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n3 = e3 |
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end |
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-- Unpack the six bit values into the 8 bit values |
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local b1, b2 = d64( e1, e2, n3, b64d_z ) |
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-- And add them to the res table |
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if e3 ~= nil and e3 ~= tail_padd64[2]:byte() then |
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out( string.char( b1, b2 ) ) |
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else |
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out( string.char( b1 ) ) |
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end |
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end |
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end |
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-------------------------------------------------------------------------------- |
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-- decode64_io_iterator |
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-- |
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-- Create an io input iterator to read an input file and split values for |
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-- proper decoding. |
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-- |
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local function decode64_io_iterator( file ) |
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local ii = { } |
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-- An enumeration coroutine that handles the reading of an input file |
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-- to break data into proper pieces for building the original string. |
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-- |
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local function enummerate( file ) |
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local sc=string.char |
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local sb=string.byte |
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local ll="" -- last line storage |
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local len |
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local yield = coroutine.yield |
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-- Read a "reasonable amount" of data into the line buffer. Line by |
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-- line is not used so that a file with no line breaks doesn't |
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-- cause an inordinate amount of memory usage. |
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-- |
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for cl in file:lines(2048) do |
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-- Reset the current line to contain valid chars and any previous |
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-- "leftover" bytes from the previous read |
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-- |
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cl = ll .. cl:gsub(pattern_strip,"") |
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-- | | |
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-- | Remove "Invalid" chars (white space etc) |
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-- | |
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-- Left over from last line |
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-- |
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len = (#cl-4)-(#cl%4) |
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-- see the comments in decode64_with_predicate for a rundown of |
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-- the results of this loop (sans the coroutine) |
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for i=1,len,4 do |
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yield( sc( d64( sb( cl, i, i+4 ) ) ) ) |
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end |
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ll = cl:sub( len +1, #cl ) |
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end |
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local l = #ll |
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if l >= 4 and ll:sub(-1) ~= tail_padd64[2] then |
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yield( sc( d64( sb( ll, 1, 4 ) ) ) ) |
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l=l-4 |
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end |
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if l > 0 then |
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local e1,e2,e3,e4 = ll:byte( 0 - l, -1 ) |
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if e1 ~= nil then |
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decode_tail64( function(s) yield( s ) end, e1, e2, e3, e4 ) |
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end |
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end |
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end |
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-- Returns an input iterator that is implemented as a coroutine. Each |
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-- yield of the co-routine sends reconstructed bytes to the loop handling |
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-- the iteration. |
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-- |
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function ii.begin() |
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local co = coroutine.create( function() enummerate(file) end ) |
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return function() |
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local code,res = coroutine.resume(co) |
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assert(code == true) |
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return res |
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end |
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end |
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return ii |
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end |
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-------------------------------------------------------------------------------- |
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-- decode64_with_ii |
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-- |
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-- Convert the value provided by a decode iterator that provides a begin |
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-- method, a tail method, and an iterator that returns four (usable!) bytes |
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-- for each call until at the end. |
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-- |
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local function decode64_with_ii( ii, out ) |
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-- Uses the iterator to pull values. Each reconstructed string |
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-- is sent to the output predicate. |
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-- |
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for l in ii.begin() do out( l ) end |
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end |
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-------------------------------------------------------------------------------- |
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-- decode64_with_predicate |
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-- |
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-- Decode an entire base64 encoded string in memory using the predicate for |
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-- output. |
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-- |
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local function decode64_with_predicate( raw, out ) |
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-- Sanitize the input to strip characters that are not in the alphabet. |
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-- |
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-- Note: This is a deviation from strict implementations where "bad data" |
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-- in the input stream is unsupported. |
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-- |
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local san = raw:gsub(pattern_strip,"") |
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local len = #san-#san%4 |
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local rem = #san-len |
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local sc = string.char |
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local sb = string.byte |
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if san:sub(-1,-1) == tail_padd64[2] then |
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rem = rem + 4 |
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len = len - 4 |
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end |
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for i=1,len,4 do |
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out( sc( d64( sb( san, i, i+4 ) ) ) ) |
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end |
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if rem > 0 then |
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decode_tail64( out, sb( san, 0-rem, -1 ) ) |
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end |
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end |
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-------------------------------------------------------------------------------- |
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-- decode64_tostring |
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-- |
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-- Takes a string that is encoded in base64 and returns the decoded value in |
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-- a new string. |
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-- |
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local function decode64_tostring( raw ) |
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local sb={} -- table to build string |
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local function collection_predicate(v) |
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sb[#sb+1]=v |
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end |
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decode64_with_predicate( raw, collection_predicate ) |
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return table.concat(sb) |
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end |
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-------------------------------------------------------------------------------- |
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-- set_and_get_alphabet |
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-- |
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-- Sets and returns the encode / decode alphabet. |
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-- |
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-- |
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local function set_and_get_alphabet(alpha,term) |
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if alpha ~= nil then |
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local magic= |
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{ |
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-- ["%"]="%%", |
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[" "]="% ", |
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["^"]="%^", |
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["$"]="%$", |
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["("]="%(", |
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[")"]="%)", |
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["."]="%.", |
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["["]="%[", |
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["]"]="%]", |
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["*"]="%*", |
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["+"]="%+", |
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["-"]="%-", |
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["?"]="%?", |
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} |
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c_alpha=known_base64_alphabets[alpha] |
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if c_alpha == nil then |
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c_alpha={ _alpha=alpha, _term=term } |
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end |
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assert( #c_alpha._alpha == 64, "The alphabet ~must~ be 64 unique values." ) |
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assert( #c_alpha._term <= 1, "Specify zero or one termination character.") |
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b64d={} -- Decode table alpha -> right shifted int values |
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b64e={} -- Encode table 0-63 (6 bits) -> char table |
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local s="" |
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for i = 1,64 do |
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local byte = c_alpha._alpha:byte(i) |
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local str = string.char(byte) |
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b64e[i-1]=byte |
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assert( b64d[byte] == nil, "Duplicate value '"..str.."'" ) |
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b64d[byte]=i-1 |
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s=s..str |
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end |
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local ext --Alias for extraction routine that avoids extra table lookups |
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if bit32 then |
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ext = bit32.extract -- slight speed, vast visual (IMO) |
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elseif bit then |
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local band = bit.band |
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local rshift = bit.rshift |
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ext = |
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function(n, field, width) |
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width = width or 1 |
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return band(rshift(n, field), 2^width-1) |
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end |
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else |
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error("Neither Lua 5.2 bit32 nor LuaJit bit library found!") |
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end |
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-- preload encode lookup tables |
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b64e_a = {} |
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b64e_a2 = {} |
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b64e_b1 = {} |
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b64e_b2 = {} |
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b64e_c1 = {} |
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b64e_c = {} |
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for f = 0,255 do |
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b64e_a [f]=b64e[ext(f,2,6)] |
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b64e_a2 [f]=ext(f,0,2)*16 |
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b64e_b1 [f]=ext(f,4,4) |
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b64e_b2 [f]=ext(f,0,4)*4 |
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b64e_c1 [f]=ext(f,6,2) |
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b64e_c [f]=b64e[ext(f,0,6)] |
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end |
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-- preload decode lookup tables |
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b64d_a1 = {} |
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b64d_a2 = {} |
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b64d_b1 = {} |
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b64d_b2 = {} |
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b64d_c1 = {} |
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b64d_z = b64e[0] |
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for k,v in pairs(b64d) do |
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-- Each comment shows the rough C expression that would be used to |
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-- generate the returned triple. |
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-- |
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b64d_a1 [k] = v*4 -- ([b1] ) << 2 |
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b64d_a2 [k] = math.floor( v / 16 ) -- ([b2] & 0x30) >> 4 |
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b64d_b1 [k] = ext( v, 0, 4 ) * 16 -- ([b2] & 0x0F) << 4 |
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b64d_b2 [k] = math.floor( v / 4 ) -- ([b3] & 0x3c) >> 2 |
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b64d_c1 [k] = ext( v, 0, 2 ) * 64 -- ([b3] & 0x03) << 6 |
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end |
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if c_alpha._term ~= "" then |
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tail_padd64[1]=string.char(c_alpha._term:byte(),c_alpha._term:byte()) |
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tail_padd64[2]=string.char(c_alpha._term:byte()) |
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else |
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tail_padd64[1]="" |
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tail_padd64[2]="" |
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end |
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local esc_term |
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if magic[c_alpha._term] ~= nil then |
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esc_term=c_alpha._term:gsub(magic[c_alpha._term],function (s) return magic[s] end) |
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elseif c_alpha._term == "%" then |
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esc_term = "%%" |
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else |
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esc_term=c_alpha._term |
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end |
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if not c_alpha._strip then |
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local p=s:gsub("%%",function (s) return "__unique__" end) |
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for k,v in pairs(magic) |
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do |
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p=p:gsub(v,function (s) return magic[s] end ) |
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end |
|||
local mr=p:gsub("__unique__",function() return "%%" end) |
|||
c_alpha._strip = string.format("[^%s%s]",mr,esc_term) |
|||
end |
|||
assert( c_alpha._strip ) |
|||
pattern_strip = c_alpha._strip |
|||
local c =0 for i in pairs(b64d) do c=c+1 end |
|||
assert( c_alpha._alpha == s, "Integrity error." ) |
|||
assert( c == 64, "The alphabet must be 64 unique values." ) |
|||
if esc_term ~= "" then |
|||
assert( not c_alpha._alpha:find(esc_term), "Tail characters must not exist in alphabet." ) |
|||
end |
|||
if known_base64_alphabets[alpha] == nil then |
|||
known_base64_alphabets[alpha]=c_alpha |
|||
end |
|||
end |
|||
return c_alpha._alpha,c_alpha._term |
|||
end |
|||
-------------------------------------------------------------------------------- |
|||
-- encode64 |
|||
-- |
|||
-- Entry point mode selector. |
|||
-- |
|||
-- |
|||
local function encode64(i,o) |
|||
local method |
|||
if o ~= nil and io.type(o) == "file" then |
|||
local file_out = o |
|||
o = function(s) file_out:write(s) end |
|||
end |
|||
if type(i) == "string" then |
|||
if type(o) == "function" then |
|||
method = encode64_with_predicate |
|||
else |
|||
assert( o == nil, "unsupported request") |
|||
method = encode64_tostring |
|||
end |
|||
elseif io.type(i) == "file" then |
|||
assert( type(o) == "function", "file source requires output predicate") |
|||
i = encode64_io_iterator(i) |
|||
method = encode64_with_ii |
|||
else |
|||
assert( false, "unsupported mode" ) |
|||
end |
|||
return method(i,o) |
|||
end |
|||
-------------------------------------------------------------------------------- |
|||
-- decode64 |
|||
-- |
|||
-- Entry point mode selector. |
|||
-- |
|||
-- |
|||
local function decode64(i,o) |
|||
local method |
|||
if o ~= nil and io.type(o) == "file" then |
|||
local file_out = o |
|||
o = function(s) file_out:write(s) end |
|||
end |
|||
if type(i) == "string" then |
|||
if type(o) == "function" then |
|||
method = decode64_with_predicate |
|||
else |
|||
assert( o == nil, "unsupported request") |
|||
method = decode64_tostring |
|||
end |
|||
elseif io.type(i) == "file" then |
|||
assert( type(o) == "function", "file source requires output predicate") |
|||
i = decode64_io_iterator(i) |
|||
method = decode64_with_ii |
|||
else |
|||
assert( false, "unsupported mode" ) |
|||
end |
|||
return method(i,o) |
|||
end |
|||
set_and_get_alphabet("base64") |
|||
--[[**************************************************************************]] |
|||
--[[****************************** Module **********************************]] |
|||
--[[**************************************************************************]] |
|||
function p.base64(frame) |
function p.base64(frame) |
||
| Line 743: | Line 19: | ||
encode = args.encode |
encode = args.encode |
||
yesno(encode, false) |
yesno(encode, false) |
||
-- encoding |
|||
local function enc(data) |
|||
return ((data:gsub('.', function(x) |
|||
local r,b='',x:byte() |
|||
for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end |
|||
return r; |
|||
end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x) |
|||
if (#x < 6) then return '' end |
|||
local c=0 |
|||
for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end |
|||
return b:sub(c+1,c+1) |
|||
end)..({ '', '==', '=' })[#data%3+1]) |
|||
end |
|||
-- decoding |
|||
local function dec(data) |
|||
data = string.gsub(data, '[^'..b..'=]', '') |
|||
return (data:gsub('.', function(x) |
|||
if (x == '=') then return '' end |
|||
local r,f='',(b:find(x)-1) |
|||
for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end |
|||
return r; |
|||
end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x) |
|||
if (#x ~= 8) then return '' end |
|||
local c=0 |
|||
for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end |
|||
return string.char(c) |
|||
end)) |
|||
end |
|||
if (encode == true) then |
if (encode == true) then |
||
enc(data) |
|||
return |
return r |
||
{ |
|||
encode = encode64, |
|||
decode = decode64, |
|||
alpha = set_and_get_alphabet, |
|||
} |
|||
else |
else |
||
dec(data) |
|||
return |
return r |
||
{ |
|||
encode = encode64, |
|||
decode = decode64, |
|||
alpha = set_and_get_alphabet, |
|||
} |
|||
end |
end |
||
end |
end |
||
return p |
return p |
||
Revision as of 14:59, 14 January 2021
Documentation for this module may be created at Module:Base64/doc
-- Made by [[User:Celeste]] - Licensed under GPLv3
local p = {}
local yesno = require('Module:Yesno') -- invoke Yesno
local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/' -- You will need this for encoding/decoding
function p.base64(frame)
local args
local data
local encode
if frame == mw.getCurrentFrame() then
args = frame.args
else
args = frame
end
data = args.data
encode = args.encode
yesno(encode, false)
-- encoding
local function enc(data)
return ((data:gsub('.', function(x)
local r,b='',x:byte()
for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
return r;
end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
if (#x < 6) then return '' end
local c=0
for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
return b:sub(c+1,c+1)
end)..({ '', '==', '=' })[#data%3+1])
end
-- decoding
local function dec(data)
data = string.gsub(data, '[^'..b..'=]', '')
return (data:gsub('.', function(x)
if (x == '=') then return '' end
local r,f='',(b:find(x)-1)
for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
return r;
end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
if (#x ~= 8) then return '' end
local c=0
for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end
return string.char(c)
end))
end
if (encode == true) then
enc(data)
return r
else
dec(data)
return r
end
end
return p