Computers have often been used to factor large numbers—and not just by number theorists having some fun. In fact, factoring such numbers has helped to test the world’s most powerful computer systems, to promote designs of new algorithms, and in cryptography used by people who need to protect sensitive information on their computers. For example, in 1978 several computer experts proposed using the reconstruction of the prime numbers from the product of two large prime numbers as an encryption technique. This method of encrypting sensitive data soon blossomed, especially because of the needs of the military and banking industry. The public also reaped the benefit of this idea as it eventually led to encryption methods such as the public-key encryption for banking and personal pages on the Internet.