John's crossword

2. a secret system of writing, used for sending messages so that no one can understand them unless they know the system
4. to put information into code (=a system of words, numbers, or symbols that hides its real meaning)
5. using letters and numbers
7. a system of sending messages using signals of sound or light that represent the letters of the alphabet
9. to succeed in understanding the meaning of a message written in code
10. to change information that was in a code that could not be read or understood into a form that can be read and understood
11. a secret message written in code
13. a short flash of light or sound used in Morse code (=a system for sending messages, used especially in the past)
15. to succeed in understanding the meaning of something written in a secret system of letters or symbols called a code
16. a system for sending messages in which you hold two flags in various positions to represent different letters and numbers
17. if someone breaks a code (=a secret way of writing), they learn how to understand it
18. a long signal used for sending messages in Morse code. Short signals are called dots.

1. marked with letters or numbers that give information
2. a name for someone or something that you use when you want to keep their real name secret
3. a way of keeping Internet messages secret in which a single key (=letter or number) changes the message into code and back again
6. the use of codes to put information on a website into a form that can only be read by users with permission
8. to put secret information into code (=a system of words, numbers, or symbols that hides its real meaning)
12. a secret system of writing, used for sending messages so that no one can understand them unless they know the system
14. completely automated public Turing test to tell computers and humans apart
16. a quick way of writing that uses symbols to represent letters, words, or phrases, used especially when you write what someone is saying as they are talking