Cryptocurrency’s Guardian: Kerckhoffs’ Principle and Private Keys
The Significance of Private Keys in Cryptography
Have you ever questioned why Bitcoin’s source code is openly accessible despite security concerns?
For Bitcoin, the public disclosure of codes is a commitment to transparency and openness, as it allows anyone to examine its inner workings. Here, Kerckhoffs’ Principle plays an important role in the development of cryptographic innovations.
Kerckhoffs’ principle states: The private key must be secret, while the algorithm itself can be public.
Private keys are vital for protecting digital assets and ensuring secure transactions in cryprocurrency.
Kerckhoffs’ Principle
The principle was formulated by Auguste Kerckhoffs, a Dutch linguist, in the late 19th century. Kerckhoffs’ best-known work in cryptography is his 1883 paper “La Cryptographie Militaire (Military Cryptography)”.
In the paper, Kerckhoffs outlined principles for the design of secure military cryptosystems:
- The system should be easy to use and implement.
- The system should be able to withstand cryptanalysis.
- The system should be able to be used to transmit a wide variety of data.
- The security of a cryptosystem should not rely on the secrecy of the algorithm, but rather on the secrecy of the key.
Kerckhoff and Modern Cryptography
Kerckhoffs’ work has had a profound impact on the development of modern cryptography.
His principles are still used in the design of secure communication systems. Kerckhoffs’ contributions to the field have helped to make cryptography a more secure and resilient.
Public Keys and Private Keys
Private Key – The private key is a secret cryptographic key that is kept confidential by its owner. It is used for decryption and signing digital messages.
Public Key – The public key can be shared with the world. It’s derived from the private key but can only be used for encryption or verifying digital signatures.
Messages encrypted with a public key can only be decrypted with the corresponding private key. If someone has access to your private key, they can potentially decrypt your confidential data.
Remember, never share your private key, as it’s the key to your cryptocurrency funds as it allows others to take control of your digital assets secured by that key.
Mnemonic Phrase
“Mnemonic Phrase” is a list of user-friendly words or phrases used to back up and restore the private key of a cryptocurrency wallet, providing an easier way to back up and restore it.
For example, if a private key is a random string like “K8H9I7F6E5D4C3B2A1,” it can be translated into a mnemonic phrase, such as “house, apple, cat, dog, umbrella”.
Mnemonic phrases are much easier for humans to accurately store and secure compared to raw private keys represented as long hexadecimal strings. As well as private keys, losing a private key could mean losing funds forever.
Hiding Algorithms or Hiding Passwords?
According to Kerckhoffs’ Principle, the security of a system should not rely on the secrecy of its design alone.
It’s quite common for companies and even standards organizations — like with CSS encryption on DVDs — to keep the inner workings of a system a secret. [1]
Keeping system designs hidden doesn’t guarantee safety, since designs can be intercepted, stolen, or reverse-engineered. Or using Claude Shannon’s simpler version: “the enemy knows the system”. [2]
Case Study: Decryption of the Enigma Cipher
A notable historical example of this principle is the decryption of the Nazi German Enigma cipher during the Second World War.
The Allies learned everything about the Enigma machine by taking the machines, getting information from other secret services, and reading the manuals. [2]
The security of Enigma was mostly based on its intricate design, with the added layer of safeguarding the daily key, rather than its secrecy.
Enigma was deciphered by probing the mathematical foundations of its encryption and engineering specialized machines to exploit mathematical weaknesses in the encryption process.
This exapmle shows why the ‘security through obscurity’ approach relying on keeping designs confidential is considered unreliable.
While some argue that keeping the inner workings of a system secret offers short-term security, in the long run, systems published can be trusted.
In general, transparency helps identify security issues faster, even though it doesn’t necessarily guarantee success.
Bitcoin’s Transparent Design
All Bitcoin transactions are recorded on a public ledger called the blockchain, which is accessible for anyone to view. This openness allows anyone to verify transactions and promotes trust in the system. [3]
While the inner workings of the Bitcoin protocol are open source and accessible to anyone, the true security of the system relies on the secrecy of individual users’ private keys.
In a Nutshell
Kerckhoffs’ Principle, formulated in the late 19th century, continues to influence modern cryptography, including its application in secure communication systems.
Public keys can be shared openly, but the secrecy of private keys is of utmost significance to ensure the security of the blockchain networks.
This principle emphasizes the need for the secrecy of the cryptographic key while allowing the algorithm to be public. Interestingly, this principle aligns perfectly with the principles of Bitcoin’s transparent design.
Reference
[1] Barry, M. (2004). Cryptography in Home Entertainment. http://www.staroceans.org/e-book/MarkBarry/MarkBarry.html
[2] Graham-Cumming, J. (2012). A note about Kerckhoff’s Principle. https://blog.cloudflare.com/a-note-about-kerckhoffs-principle/
[3] Bitcoin.org. (n.d.). https://bitcoin.org/en/
Author
Miyoko Shimura has over 8 years of engineering experience in the technology industry bringing together analytical perspectives.
DLT Mentor at German think-tank Frankfurt School Blockchain Center and Technical Editor at Coinmonks. For further updates please follow me on LinkedIn or Twitter 🌏
Portfolio https://linktr.ee/miyokoshimura
