Encryption

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Across
  1. 2. Decoding machine used at Bletchley Park during
  2. 4. an algorithm for performing encryption and
  3. 5. appear
  4. 7. Type of analysis used to determine how often
Down
  1. 1. Code used during WW1/2 comprising dots and dashes
  2. 3. Organisation responsible for UK cyber defence
  3. 4. Person responsible for the first substitution cipher
  4. 6. an encryption method used by the ancient