File

+
−-- Prosody IM
+
−-- Copyright (C) 2008-2017 Matthew Wild
+
−-- Copyright (C) 2008-2017 Waqas Hussain
+
−-- Copyright (C) 2008-2017 Kim Alvefur
+
−--
+
−-- This project is MIT/X11 licensed. Please see the
+
−-- COPYING file in the source package for more information.
+
−--
+
−
+
−local s_gsub = string.gsub;
+
−local random_bytes = require "util.random".bytes;
+
−local base64_encode = require "util.encodings".base64.encode;
+
−
+
−local b64url = { ["+"] = "-", ["/"] = "_", ["="] = "" };
+
−local function b64url_random(len)
+
−	return (s_gsub(base64_encode(random_bytes(len)), "[+/=]", b64url));
+
−end
+
−
+
−return {
+
−	-- sizes divisible by 3 fit nicely into base64 without padding==
+
−
+
−	-- for short lived things with low risk of collisions
+
−	tiny = function() return b64url_random(3); end;
+
−
+
−	-- close to 8 bytes, should be good enough for relatively short lived or uses
+
−	-- scoped by host or users, half the size of an uuid
+
−	short = function() return b64url_random(9); end;
+
−
+
−	-- more entropy than uuid at 2/3 the size
+
−	-- should be okay for globally scoped ids or security token
+
−	medium = function() return b64url_random(18); end;
+
−
+
−	-- as long as an uuid but MOAR entropy
+
−	long = function() return b64url_random(27); end;
+
−
+
−	-- pick your own adventure
+
−	custom = function (size)
+
−		return function () return b64url_random(size); end;
+
−	end;
+
−}