Renaissance Ciphers: Encryption and Eggshells

The Renaissance ushered in a golden age of ciphers. It began in fifteenth-century Italy, where competing city-states sought to protect their communications. It continued in Elizabethan England, where Mary Queen of Scots’ encrypted letters advocating the assassination of the Queen led to her execution for treason. However, cryptography was useful to more than monarchs and spies. Anyone with access to books on the subject could learn and personalise ciphers that would conceal their private writings and lives. Here, on title pages and blank leaves, Cambridge readers have practised and adapted these ‘subtle’ arts for themselves, turning printed texts into personal codebooks.

The revival of shorthand in England was no coincidence at a time when public persona was sometimes at odds with secretly held religious views. With a little personalisation, a shorthand system could become a cipher. This measure of security made for remarkably candid writing, as in the case of Samuel Pepys’ diaries. His contemporary and the President of Queens’ College, Henry James, used the same shorthand system (popular in the colleges of Cambridge) as Pepys. James’ notes remain undeciphered.

Humanist scholars drew on classical knowledge of cryptography to produce authoritative compendia for contemporary use, some of which became part of the Old Library’s collection. Two of the authors of the books on display were arrested and interrogated by the Inquisition, which believed ciphers and their concealment of the truth to be ungodly. After his experience one of them, Giambattista della Porta, described another kind of secret writing: one could use wax and acid to leave secret messages on the inside of unbroken eggshells, because ‘eggs are not stopt by the Papal Inquisition’.