Related Clues:
- Completely closed
- Sealed, say
- Not even cracked
- Tied down
- Securely sealed
- Encrypted, perhaps
- Like an encrypted transmission, in theory
- Free from danger or risk
- Safe or fastened
- Make safe or fasten
- Safe, protected
- Safe and free from danger
- Free from danger and financially sound
- Safe against attack or well fastened
- Safe, confident