keygen3

#!/usr/bin/env ruby

# Programatic interface to the RSA key generator for Chat 3.0.
# Writes keys to ruby file installed in ~/.sechat/address_book.rb
# Last revision:  Dec 3, 2009

$LOAD_PATH.unshift File.dirname(__FILE__)

BITS = 2408
require "rsa.rb"
require 'fileutils'
require 'md5'

# File storage directory (user and server)
#FILE_DIRECTORY = (File.join(File.expand_path('~'), '.sechat') rescue '.')
FILE_DIRECTORY = '.'

# Make sure they specify a username
if ARGV.length != 1
  $stderr.puts "Usage: #{$0} <username>"
  Kernel.exit
end

# Make sure the directory exists
FileUtils::mkdir FILE_DIRECTORY rescue nil

# Warn if they're about to overwrite their key
if File.exists?("#{FILE_DIRECTORY}/address_book.rb")
  raise "You already have a key in #{FILE_DIRECTORY}/address_book.rb"
end

# Make the key pair
$stderr.puts 'Making keys, this will take a while...'
pub, prv = Key.keygen(BITS)
fingerprint = []
MD5::digest(pub.to_s)[0,8].each_byte { |x| fingerprint << ("%02x" % x) }
fingerprint = fingerprint.join(' ')

# Output the keys to the rsa_keys file
begin 
  kf = File.new("#{FILE_DIRECTORY}/address_book.rb",
                File::CREAT|File::TRUNC|File::WRONLY, 0600)
  kf.puts("# Chat client RSA keys.  KEEP THIS PRIVATE!\n\n")
  kf.puts("RSA_ADDRESS_BOOK = {")
  kf.puts("  :name => '#{ARGV[0]}',")
  kf.puts("  :pub => '#{pub.to_s}',")
  kf.puts("  :prv => '#{prv.to_s}',")
  kf.puts("}")
  kf.close
rescue
  puts "Could not write to keyfile; aborting."
  Kernel.exit
end

# Just print them to stdout
$stderr.puts "Completed!  You can now run Chat 3.0."
$stderr.puts "\nYour key fingerprint is #{fingerprint}.\n\n"