Crypto Puzzle

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Across
  1. 1. lock
  2. 4. Aeroplane
  3. 6. Data
  4. 7. Sim
  5. 9. Goal
  6. 10. hidden
  7. 11. Exam
Down
  1. 2. Security
  2. 3. Zero
  3. 5. secret writing
  4. 8. Servant
  5. 9. key