From Sixteenth-Century Cryptography to the New Millennium — The Last 500 Years - Codes: The Guide to Secrecy from Ancient to Modern Times - page 61

Secretary to Queen Elizabeth. This cryptanalysis of Philip's intentions was ac-
complished in 1577, but Philip did not invade until 1588, during which time the
English were able to fortify their defenses substantially. In fact, of the so-called
invincible armada of Spain, numbering about 130 ships and around 19 , 000 men,
only 69 ships returned to Spain and as many as 15 , 000 men perished, either in
battle or on the long voyage home. This was the first major strike at the heart
of the most powerful European power of that age, ensured by the actions of a
cryptanalyst.
Meanwhile, back in England in 1577, after receiving the deciphered cryp-
togram revealing Philip's plans for invasion, Walsingham set about to establish
a cipher school in London. He employed a man named Thomas Phelippes, as
his cipher secretary. Phelippes was destined to be the first eminent cryptanalyst
in England's history, and the downfall of Mary Queen of Scots.
After Mary lost her own throne in Scotland, and failed in a final attempt
to regain her crown, in 1568, she made the crushing mistake of fleeing south
to her cousin Queen Elizabeth hoping for asylum. (Mary Stuart was the only
child of King James V of Scotland and his French wife, Mary of Guise.) The
Queen merely imprisoned Mary, since she was too much of a threat, given that
English Catholics considered Mary to be the rightful Queen of England. Mary
spent 18 years in various prisons (actually in castles and manors, where she was
under house arrest and heavy guard). Moreover, all of her ingoing and outgoing
correspondence did not reach their destinations, that is, until January 6 of 1586,
when Gilbert Gifford, a former seminarian, smuggled a pile of correspondence
in to her that had accumulated at the French Embassy in London. The embassy
had kept the letters fearing that if sent, they would not reach Mary. Gifford
fixed that problem. Moreover, he began smuggling out letters from Mary to
others.
A young Catholic man named Anthony Babington hated Queen Elizabeth for
the atrocities committed against his family and Catholics in general at the time.
Anti-Catholic policies included public disemboweling of live victims, accused of
being traitors for the mere fact of being a loyal Catholic, or even for just being
a priest, loyal to the Vatican. Babington hatched a plot to assassinate Queen
Elizabeth and wanted Mary's blessing to do so. Gifford delivered an enciphered
letter from Mary to Babington revealing that she had heard about the plot from
her friends in France, and that she wanted to hear from him. Babington put
together an encrypted letter, outlining the details of the plot, and even added
the steganographic benefit of placing the message in a beer barrel to get past
the guards. However, all this was for naught since Gifford had been recruited
and was working for Walsingham from the outset. All Mary's correspondence
had been brought to him for Phelippes to cryptanalyze, then sealed again and
sent to their destinations with nobody in Mary's camp being any wiser.
When Gifford brought Babington's letter to Walsingham, and Phelippes
deciphered it, the plot was revealed. Yet, Walsingham was biding his time. He
let the letter go to Mary and when she responded to Babington, and Phelippes
decrypted it, this spelled the end for her. Yet, Walsingham wanted to get
everyone involved in the plot, so he had Phelippes forge a P.S. asking Babington