What is Kerckhoffs's principle in cryptography?

Kerckhoffs's principle is a foundational rule in cryptography stating that a cryptosystem should remain secure even if all its details, except the key, are public knowledge. Formulated by the Dutch cryptographer Auguste Kerckhoffs in the 19th century, it stands in direct opposition to security through obscurity. It is also famously known as Shannon's maxim when phrased by Claude Shannon as the assumption that the enemy knows the system completely.

What we know

• Kerckhoffs's principle holds that a cryptosystem should remain secure even if everything except the key is public knowledge. [2]
• The principle was stated by the Dutch cryptographer Auguste Kerckhoffs during the 19th century. [2, 4]
• American mathematician Claude Shannon phrased the principle as 'the enemy knows the system', naming it Shannon's maxim. [2]
• The principle contrasts sharply with security through obscurity, which cryptographers widely reject. [2]

Where to go next

• whoWho was Auguste Kerckhoffs?
• compared withWhat is security through obscurity?
• how we knowWhat did Claude Shannon contribute to information theory?
• the bigger pictureHow does modern cryptography protect data confidentiality?
• a case in pointWhat are historical mechanical ciphers like Enigma?
• an unexpected connectionHow does intelligence agencies' hardware testing reflect Kerckhoffs's principle?The principle is so deeply trusted that a former NSA official noted the standard assumption was that device serial number one was delivered straight to the Kremlin.

Sources

• [1]Kerckhoffs’s principle (Wikidata Q1331187) · CC0 1.0
• [2]Kerckhoffs's principle · CC BY-SA 4.0
• [3]History of cryptography · CC BY-SA 4.0
• [4]Auguste Kerckhoffs · CC BY-SA 4.0
• [5]Cryptography · CC BY-SA 4.0

Your path

1. Who was the American philosopher Michael Martin?
2. /What is Kerckhoffs's principle in cryptography?