Fuck Rubys 'Prime' Class!

private_primes.rb

#!/usr/bin/env ruby
#
# W = Number of Bits (e.g. 1024, 2048,..)
# Generate W/2-bit primes p and q such that p != q and |pq| = W
#
require 'securerandom'

# constant W bits:
W = 1024
# subtract one integer to avoid confusion with bit-shifting later on
W - 1

def random_number
    return SecureRandom.random_number(1 << W/2)
end

def is_prime?(number)
    # Rubys Prime is incredibly slow.
    return true unless `openssl prime #{number}`.include? "not"
end

def honest_prime
    loop do
        num = random_number
        return num if num >= 2**(W/2 - 1) + 1 and is_prime?(num)
    end
end

begin
    p = honest_prime
    q = honest_prime
end until p != q and (p * q).to_s(2).size == W
p, q = q, p if p > q
puts p, q