class OpenSSL::PKey::DH

with SSH functionality.
have been added to it by the Net::SSH module for convenience in dealing
This class is originally defined in the OpenSSL module. As needed, methods

def valid?

lifted more-or-less directly from OpenSSH, dh.c, dh_pub_is_valid.)
Determines whether the pub_key for this key is valid. (This algorithm 
def valid?
  return false if pub_key.nil? || pub_key < 0
  bits_set = 0
  pub_key.num_bits.times { |i| bits_set += 1 if pub_key.bit_set?(i) }
  return (bits_set > 1 && pub_key < p)
end