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.

  • Bpsic 2845631e3e5e9f10cbc7d007d74ce89d
  • Banbury Sheets 01 9d90529f46629d0424e2d447ecea7a3e
  • Banbury Sheets 02 1c96ece6f2e69aa3847e19e3947033a5
  • Banbury Sheets 03 5406015b7cea71d48a6b8b657ce1eeb5
  • Banbury Sheets 04 E82e6fe8ef4a344b6e86f4d9d27c50e4
  • Collossus 5762952793a395053851f9b9dab8fa69

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.