Encryption

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