Possible Clues:

• Encrypted
• Like secret messages
• Like some messages
• Like this: CFXBSF UIF JEFT PG NBSDI
• 12 9 11 5 20 8 9 19 3 12 21 5
• One way to communicate
• How some diplomats communicate
• Encrypted, as a message
• Popular commander of French using secret language
• Rendered unreadable