#!/usr/bin/env ruby

seed = '31416406127362175889'
user = 'jmerchat'
pass = 'foobar'
passh = '81A8E60EBBA84D55DFADA361F73B0A8937F0B11A'
hash = 'ugACQkL4CKlnCZo44zVHNQJYFid1giy1MBEME0pglhzgwxctODvJgOMrKZD6uDBO7%2F1BaiIfwR0h6vieLcMODxm5fd63M9gQhs%2BnEgWfuA%3D%3D'

require 'enumerator'
require 'cgi'
require 'digest/sha1'
require 'zlib'

def sha1(str)
	Digest::SHA1::hexdigest(str)
end

def crc32(str)
	'%x' % Zlib.crc32(str)
end

# cree une table de permutation
def mktable(seed)
	arr = [*0..255]
	j = 0
	256.times { |k|
		j += arr[k] + seed[k % seed.length]
		j &= 255
		arr[j], arr[k] = arr[k], arr[j]
	}
	arr
end

# xore chaque octet de authstr avec un nombre calcule a partir
# de la table de permutation, refait une inversion dans la table a
# chaque iteration
def foo(authstr, passh)
	shuf = mktable(passh)
	
	k = 0
	# authstr must not exceed 255 chars
	authstr.unpack('C*').to_enum(:each_with_index).map { |c, i|
		i += 1
		k += shuf[i]
		k &= 255
		shuf[i], shuf[k] = shuf[k], shuf[i]
		
		shuf[(shuf[i] + shuf[k]) & 255] ^ c
	}.pack('C*')
end


def mkauth(randseed, user, passh)
#	passh = sha1(pass)
	authstr = randseed + ':' + user + ':' + sha1(passh)
	# rajoute le crc de ce qui precede
	authstr += ':' + crc32(authstr)
	
	foo(authstr, passh)
end

# base64 encode la chaine
puts CGI.escape([mkauth(seed, user, passh)].pack('m').chomp)
puts hash

foobared = CGI.unescape(hash).unpack('m').first
notbared = seed + ':' + user + ':'

p foo(CGI.unescape(hash).unpack('m').first, passh)
#p notbared.unpack('C*').zip(foobared.unpack('C*')).map { |a, b| a ^ b }