06 February 2015

Top-secret "Banbury sheets" discovered at Bletchley Park

Bletchley Park, home of Extra Technology's Milton Keynes office, is in the news as top-secret WW2 "Banbury sheets", are discovered stuffed into the ceilings and walls of a codebreaking hut.

Extra Technology enjoys having an office at Bletchley Park. The site has immense historical significance in the world of Computing (and indeed to WW2). 'Block H' is the world's first purpose-built computer centre, constructed in 1944 to accommodate Colossus computers. Colossus is widely acknowledged as the world's first modern computer, designed with a single purpose: to help decipher the encrypted messages between Hitler and his generals during World War II.

Bletchley Park is once again in the news as once top-secret "Banbury sheets" (utilised by mathematician Alan Turing's Banburismus process to accelerate the decryption of the German Enigma code) have been discovered stuffed into the ceilings and walls of a World War Two codebreaking hut.

  • Bletchley Park Science and Innovation Centre
  • Banbury Sheets
  • Banbury Sheets
  • Banbury Sheets
  • Banbury Sheets
  • Collossus

The principle behind Banburismus is relatively simple; if two sentences in English or German are written down one above the other, and a count is made of how often a letter in one message is the same as the corresponding letter in the other message; there will be more matches than would occur if the sentences were random strings of letters. For a random sequence, the repeat rate for single letters is expected to be 1 in 26 (around 3.8%), and for the German Navy messages it was shown to be 1 in 17 (5.9%). If the two messages were in depth, then the matches occur just as they did in the plaintexts.

The comparison of two messages to look for repeats was made easier by punching the messages onto thin cards. The cards were printed in Banbury, England. They became known as 'banburies' at Bletchley Park, and hence the procedure using them was Banburismus.

The National Museum of Computing resides at Bletchley Park. The Museum has fantastic exhibits,showing how computing had radically changed our lives. It offers a fascinating tour for all of us (not only technically-minded 'propeller heads'). Maybe the most famous exhibit is a fully working replica of Collossus.

Friends, partners and customers of Extra Technology are welcome join us on a complimentary tour of Bletchley Park and The National Museum of Computing. Please contact your Extra Technology representative to arrange your visit or leave us a message here.