Code making and code breaking: John Dee and the art of cryptography

One of the rare 16th-century books displayed in the current RCP exhibition ‘Scholar, courtier, magician: the lost library of John Dee’ is the Polygraphie et universelle escriture cabalistique by Johannes Trithemius (Paris, 1561).

The German abbot Trithemius (1462–1516) is an important name in the history of cryptography – the science and art of making and breaking codes – and also in the history of occult studies. Trithemius wrote about code breaking and about communication using spirits, both topics known to interest John Dee. In 1564, while Dee was staying in the city of Antwerp, he managed to track down a manuscript copy of Trithemius’ most famous work, the Steganographia, and to borrow it so that it could be copied out.

The Polygraphie (also known in Latin as the Polygraphia) is the first printed book about the subject of cryptography. The copy owned by Dee contains practical devices, cipher discs, to help the reader encrypt or decrypt text. There are 12 rotating paper discs known as ‘volvelles’. They are in remarkably good condition, and still turn today.

Polygraphie et universelle escriture cabalistique. Johannes Trithemius, published Paris, 1561

Cryptography was a life and death matter in Tudor England, no mere abstract study. In a new interview filmed last year, Simon Singh explains its importance during the reign of Elizabeth I, no more dramatically illustrated than via the foiled Babbington plot.

Dee's known interests in cryptography and wide travels across Europe have long suggested to later writers that he might have been a spy. Robert Hooke suggested that Dee's ‘book of spirits’ – his records of conversations with angelic beings and of the ‘Enochian’ language they revealed to him – was actually a book of code.

To come then to the book it self. Upon turning it over, and comparing several Particulars in it one with another, and with other Writings of the said Dr Dee ... so far as I can be informed, I do conceive that the greatest part of the said Book, especially all that which related to the Spirits and Apparitions, together with their Names, Speeches, Shews, Noises, Clothing, Actions, and the Prayers and Doxologies, &c. are all Cryptography ... that is, under those feignd Stories, which he there seems to relate as Matters of Fact, he hath concealed Relations of quite another thing; and that he made use of this way of obsconding it, that he might the more securely escape discovery, if he should fall under the suspition as to the true Designs of his Travels ... conceiving that the Inquisition that should be made, or Prosecution, if discovered, would be more gently for a Pretended Enthusiast, than for a real Spy.

The Posthumous Works of Robert Hooke. Robert Hooke, published London, 1705.

The 1968 book John Dee: scientist, geographer, astrologer and secret agent to Elizabeth I, written by Richard Deacon, makes further claims about Dee’s involvement in espionage.  Deacon claims that Dee signed his letters to Elizabeth with a secret sign, or cipher, which looks like '007'. Many people now suggest that this cipher was an inspiration to Ian Fleming, creator of the famous fictional secret agent James Bond. However, while researching 'Scholar, courtier, magician' we have found no evidence that Dee ever signed his letters this way.

Katie Birkwood, rare books and special collections librarian

‘Scholar, courtier, magician: the lost library of John Dee’ opens on Monday 18 January and runs until Thursday 28 July 2016.

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