What is the purpose of a digital signature?

A digital signature serves as an electronic means of authentication, ensuring that the sender of a message is verified. It provides integrity and authenticity to digital communications by binding the identity of the sender to the message itself. When a sender signs a document digitally, it creates a unique fingerprint of the document that can be validated by the recipient, thus confirming that the message was not altered in transit and indeed comes from the claimed sender.

The technology behind digital signatures relies on cryptographic algorithms that create a unique signature based on the contents of the message and the sender's private key. This ensures that only the sender, who possesses the corresponding private key, can create a valid signature. Recipients can use the sender's public key to verify the signature, effectively confirming the sender's identity and that the content is intact.

Other choices do not align with the core function of digital signatures. For instance, encryption methods are designed to secure data transmission by making data unreadable to unauthorized users, while file compression methods aim to reduce the size of digital files for easier storage or transfer. Digital currencies, on the other hand, are a form of payment executed electronically and are unrelated to the purpose of verifying identity and authenticity in digital communications.