Lua base64 encoder/decoder

Pure Lua base64 encoder/decoder. Works with Lua 5.1+ and LuaJIT. Fallbacks to pure Lua bit operations if bit/bit32/native bit operators are not available.

local base64 = require'base64'
local str = 'Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.'
local b64str = 'TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlzIHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRoZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=' 
local encoded = base64.encode( str )
local decoded = base64.decode( b64str )
assert( str == decoded )
assert( b64str == encoded )

base64.encode( str, encoder = DEFAULT, usecache = false )

Encodes str string using encoder table. By default uses table with + as char for 62, / as char for 63 and = as padding char. You can specify custom encoder. For this you could use base64.makeencoder. If you are encoding large chunks of text (or another highly redundant data) it's possible to highly increase performace (for text approx. x2 gain) by using usecache = true. For binary data like images using cache decreasing performance.

base64.decode( str, decoder = DEFAULT, usecache = false )

Decodes str string using decoder table. Default decoder uses same chars as default encoder.

base64.makeencoder( s62 = '+', s63 = '/', spad = '=' )

Make custom encoding table

base64.makedecoder( s62 = '+', s63 = '/', spad = '=' )

Make custom decoding table

Install

luarocks install base64