What is the main function of a digital signature?

The main function of a digital signature is to verify the authenticity and integrity of a message. Digital signatures use cryptographic techniques to provide a unique fingerprint of a message, which ensures that the message has not been altered in transit and confirms the identity of the sender. When a sender creates a digital signature, they use their private key to sign the message, which can then be verified by the recipient using the sender's public key. This process provides assurance to the recipient that the message indeed comes from the claimed sender and that the contents remain unchanged.

The importance of this function in cybersecurity cannot be overstated, as it plays a critical role in ensuring secure communications over the internet, preventing impersonation, and maintaining trust in electronic transactions. In contrast, the other options relate to different functions unrelated to the primary purpose of digital signatures. For example, encrypting data is related to confidentiality, enhancing speed of transmission does not directly relate to security, and creating backups pertains to data preservation rather than authenticity and integrity verification.