1605
Francis Bacon first uses binary

Sir Francis Bacon (22 January 1561 – 9 April 1626) was an English philosopher and scientist. In 1605 he published details of a new code cipher he had developed, now called Bacon's Cipher. This cipher uses 5 character sequences of two letters, a and b, to encode all the letters of the alphabet, as follows:

• A is encoded as aaaaa
• B is encoded as aaaab
• C is encoded as aaaba
• D is encoded as aaabb
• and so on...

For example the message "BACON" would be:

aaaab aaaaa aaaba abbab abbaa

In Bacon's cipher, all letters are encoded as combinations of just two symbols. This is called a binary encoding. The actual symbols used are arbitrary. Bacon's cipher uses a and b, while computers now use 0 and 1. Bacon's ciper is the first time binary was used to encode letters.

You might have already spotted a problem with Bacon's cipher: there are only 24 different combinations of a 5 character binary sequence, but there are 26 letters in the alphabet. In Elizabethan times, when Francis Bacon invented the code, the letters I and J were the same letter, as were U and V. So the Elizabethan alphabet only contained 24 letters, and could be fully represented using Bacon's cipher.

Related information:

• Bacon's cipher – Encrypt and decrypt online

Image:

• Francis Bacon, 1st Viscount St Alban by Unknown artist. Oil on canvas. NPG 1288
  Credit: © National Portrait Gallery, London, Creative Commons BY-NC-ND 3.0

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