derrick by mamapeirong

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									Colossus
                Colossus
• Designed in March of 1943 by Tommy Flowers,
  Max Newman, et al. and Mark 1 was completed
  by December, 1943 as a means to quickly
  decipher the Lorenz Cipher a.k.a. “Fish”
• Was an improvement upon Newman’s earlier
  machine, the Heath Robinson
• Consisted of 1500 valves that generated the
  Lorenz Cipher while the message was read from
  a tape at 5000 characters per second
             Baudot Code
• 31 + 1 symbols represented as 5
  “channels,” each being either marked or
  not.




                     Image Source: http://www.funkfreund.de/
Lorenz Machine (SZ-40 and SZ-42)
• Had 12 wheels, divided into 3 groups of 5 (K), 5
  (S), and 2 (M).
• K and bigger M wheel moved once per
  character; smaller M wheel moved if other M
  wheel was active; S moved if both M wheels
  were active
• Number of positions on each wheel are relatively
  prime (41, 31, 29, 26, 23 for K; 43, 47, 51, 53, 59
  for S; 37, 61 for M)
• One wheel in K and S were inverted
              Lorenz Cipher
• XOR’ed the 2 values generated by the K and S
  wheels with the letter of the message in Baudot
  Code
• Decryption was dependent on the initial 12-
  letters which synchronized wheels on both
  machines
• Was broken by Bill Tutte, John Tiltman et al.
  after the retransmission of a large message
  using the same initial setting
• Messages required 4-6 weeks to decipher by
  hand
             Colossus contd.
• Computation time synchronized to read time
• Incorporated primitive double buffering
• Is the first known machine to have shift registers,
  constructed out of triodes called thyratrons
• Programming was done by reconnecting wires
  between AND and OR gates
• Colossus deciphered messages sent in Lorenz
  code in hours, as much time as a computer in
  1996 would have needed
               Misc Facts
• Total of 10 were built—the Mark 1 and 9
  Mark 2’s
• Was not designed by Alan Turing, though
  his work went into the deciphering of the
  Lorenz Cipher
• Influenced Turing’s design of his Universal
  Machine (ACE)
• Reconstruction project at Bletchley Park
  by curator Tony Sale
                Sources
• http://www.codesandciphers.org.uk/lorenz/
• http://en.wikipedia.org/wiki/Lorenz_cypher
• http://fn2.freenet.edmonton.ab.ca/~jsavard
  /crypto/te0301.htm
• http://www.turing.org.uk/turing/
• http://www.eclipse.net/~dhamer/lorenz.htm

								
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