A cryptographic system should be secure even if everything about it, except the key, is public.
Kerckhoffs stated it in 1883, and Shannon restated it as the enemy knows the system. It is why published, peer-reviewed algorithms are more trusted than proprietary secret ones.
In practice
- A lock is trusted because its mechanism is published and has resisted attack, not because the manufacturer will not say how it works.
- A voting system whose source is public and audited is more trustworthy than one whose security rests on nobody seeing it.
- Further reading
- Wikipedia
- Subject
- Technology & Software
- Essay
- Design rules that engineers pass down