Robert Hannigan, the Director of British intelligence agency GCHQ, gave a speech at MIT recently on the currently contentious issue of backdoors into encryption.

To accompany his speech, and maybe to reaffirm GCHQ’s credentials on the subject, he published two papers written by James Ellis in 1970 about what would become public key encryption: “The Possibility of Secure Non-Secret Digital Encryption” and “The Possibility of Secure Non-Secret Analogue Encryption”.

The story famously goes that two decades after Rivest, Shamir and Adleman announced the RSA algorithm for public key cryptography, GCHQ admitted that their employee Clifford Cocks had come up with essentially the same thing four years before, inspired by James Ellis’s papers on the possibility of cryptography without a secret key.

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Rober Hannigan’s speech, Front doors and strong locks: encryption, privacy and intelligence gathering in the digital era.

**Read the papers: **“The Possibility of Secure Non-Secret Digital Encryption” and “The Possibility of Secure Non-Secret Analogue Encryption” by James Ellis.