Why Public-Key Cryptography Matters

Why Public-Key Cryptography Matters

Gov CIO Outlook | Thursday, May 12, 2022

Public and private key pairs are used in public-key encryption, which relies on public keys. To distinguish it from other forms of encryption, this one uses public keys rather than the more common private ones.

FREMONT, CA: Public-key cryptography, which is 40 years old and as important now as it was when it was established, is the unsung hero of modern cybersecurity. Many times a day, the majority of individuals utilize it unknowingly. What is it, and how does it function?

Let's begin by studying the notion of symmetric encryption, which allows you to encrypt data using a secret key shared between parties. It's not a new concept; Julius Caesar employed it to encrypt his messages.

Symmetric encryption enables the secure communication of information between two or more parties, provided that all participants securely share the same secret key (used to encrypt and decrypt the information). While this is an excellent method for sharing information with a trusted partner who also shares the key, how do you communicate securely with someone you have never met or who is not in the exact physical location? How can you safely distribute an encryption key without the risk of it being intercepted (not by Roman foes, but by cybercriminals)?

Asymmetric encryption, also known as public-key cryptography, tackles this issue by employing two keys: public and private. Only the private key can decrypt messages encrypted using the public key, and vice versa.

In 1977, the founders of RSA patented a technique that employs mathematical "trapdoor" functions to create keys. These algorithms can readily use many inputs to generate a result, but it is computationally challenging to findștiinputs from a given output.

Public-key cryptography has three principal advantages: Confidentiality, Authenticity, and Non-repudiation.

These advantages have revealed numerous uses for public-key cryptography, including PGP, HTTPS, OIDC, and WebAuthN. It is also used for secure shell certificates, allowing administrators to connect to servers without remembering their passwords.

The continuous usage of public-key encryption raises various difficulties, particularly in administering certificates. The cryptographic keys used to encrypt and sign messages are contained within digital certificates issued by certificate authorities (CAs)—trusted centers for authenticating identities. The term for this ecosystem is public critical infrastructure (PKI).

Unfortunately, PKI has a history of problems. In 2011, the Dutch CA DigitNotar went out of business after its infrastructure was compromised and fake certificates were issued.

Another mathematical threat to public-key cryptography is a mathematical one. Trapdoor functions are partly dependent on the difficulty of factoring huge prime integers, which are employed to generate the keys. If someone discovered a method for quickly locating huge prime numbers and then used that method to solve the prime factorization issue, public-key cryptography would collapse.

Currently, this is not a pressing issue, but researchers are aggressively developing quantum computing, which will enable brute-force execution by computers. These machines claim to be able to answer complex math problems by testing each iteration of a problem continuously instead of sequentially. The National Institute of Standards and Technology (NIST) is already planning for this, and it is hoped that a solution will be found before the full manifestation of the problem.

Public key cryptography can be challenging to comprehend and build from scratch, but developers are fortunate to access numerous libraries that do the hard work. The renowned Networking and Cryptography Library (NaCl) provides an API known as the Box API that simplifies the management of public-key cryptography. There are NaCl implementations in every primary programming language. If you want to implement public-key cryptography, please utilize either the NaCl or libsodium libraries, as they have been thoroughly reviewed, tested, and are actively updated.

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