What is a primary use of a public-key cryptosystem?

A primary use of a public-key cryptosystem is for digital signatures. In this context, public-key cryptography enables the creation and verification of digital signatures, which play a vital role in ensuring the authenticity and integrity of a message or document. When a sender digitally signs a message using their private key, anyone with access to the sender's public key can verify that the message has not been altered and indeed originated from the purported sender. This process helps in establishing trust in electronic communications, which is essential for secure online transactions and communications.

Digital signatures are particularly important because they serve as a mechanism for non-repudiation; that is, they prevent the sender from denying having sent the message, since only they possess the private key needed to create the digital signature. Moreover, digital signatures are widely used in various applications, including securing software distribution, financial transactions, and ensuring the legal enforceability of electronic contracts.

While public key distribution is an essential aspect of public-key cryptography, it primarily facilitates the sharing of public keys for encryption and signature verification rather than being a primary use itself. Hashing, on the other hand, is a separate cryptographic function that transforms data into a fixed size, which does not involve public-key systems directly. The