What is the primary purpose of using a digital signature in email?

The primary purpose of using a digital signature in email is to provide non-repudiation. This means that the sender cannot deny having sent the message, as the digital signature uniquely identifies them and confirms their authenticity. Digital signatures are created using the sender's private key, which is part of a public key infrastructure. Recipients can verify the signature using the sender's public key, ensuring that the message has not been altered and confirming the identity of the sender.

By enabling non-repudiation, digital signatures enhance the trustworthiness of email communications, particularly in legal or formal contexts, where it is critical to verify the origin and integrity of the message. This assurance helps build confidence in electronic communications, as both the sender and receiver can rely on the authenticity of the email.

The other choices do not accurately reflect the primary function of digital signatures. For instance, while encryption protects the content of messages, it does not confirm the identity of the sender or ensure message integrity in the same way digital signatures do. Data compression relates to reducing file sizes, which is not a function of digital signatures, and enhancing speed is unrelated to the purpose of using digital signatures in email communication.