i'm not exactly sure what, and why, the phpBB people are doing this crazy custom hashing. but if you ever need to authenticate against a phpBB user table, this gem will help you do exactly that.
just include mram-phpbb_hash in your Gemfile, and use it like this:
inputpass = params[:password] # from post variables, for example
phpbbhash = get_hash_from_phpbb_database(params[:user]) # whatever you need to do to get the hash from the database
if Mram::PhpbbHash.check_hash(inputpass, phpbbhash) then
puts "success!"
else
puts "hash does not match!"
end
the actual code was translated to ruby by me from phpBB 3 Sources. appearently, there was no other gem doing this so far..