From Sixteenth-Century Cryptography to the New Millennium — The Last 500 Years

The age of chivalry is gone. That of sophists, economists, and calculators, has succeeded; and the glory of Europe is extinguished forever.

Edmund Burke (1729-97), Irish-born whig politician and writer — from Reflections on the Revolution in France (1790)

We begin with cryptographic tales surrounding the French, British, and Spanish monarchs in the sixteenth century. In 1556, Philip II of Spain ascended to the throne. In that year, he decided to discard the (deeply compromised) ciphers used by his father Charles V. Philip turned to an idea of Giovani Soro (a cryptographer we discussed in Section 1.5 (see page 58), by dividing his cryptosystems into two sets: cifra general, used for communications between the king and his ambassadors; and cifra particular, used by an individual messenger and the king. Philip’s use of Soro’s ideas became the template for Spanish cryptography well into the seventeenth century.