Related Clues:

• Member org. of the Five Eyes alliance
• Govt. employer of cryptologists
• Org. behind an encrypted recruitment tweet
• Intelligence org. with a Cryptologic Museum
• Org. concerned with cyberwarfare
• Very secretive org
• Code crackers' org
• Org. that may spot an unintended secret message in this puzzle
• Intel analyst's org
• SIGINT org
• Secret letters?
• Unit with a classified no. of employees
• Casual dating letters
• PRISM org
• Secretive group, initially