Cocks was beginning to formulate what would later be known as the RSA asymmetric cipher. Rivest, Shamir and Adleman discovered their formula for public key cryptography in 1977, but four years earlier the young Cambridge graduate was going through exactly the same thought processes. Cocks recalls: “From start to finish, it took me no more than half an hour. I was quite pleased with myself. I thought, ‘Ooh, that’s nice. I’ve been given a problem, and I’ve solved it.’ ”
