Related Clues:

• Deco's stylised rules
• Convert into a cipher
• Secret symbols
• Put (message) into ciphers
• Cryptographic system
• System of rules
• System of signals
• Secret system of letters. words etc
• Cipher — set of principles
• Rule book
• Render unreadable, in a way
• Building inspector's expertise
• Put in a secret language
• Make unreadable to the enemy
• Cryptologist's interest