What is the function of the public key in the context of digital signatures?

In the context of digital signatures, the function of the public key is to validate the authenticity of a decrypted message. When a sender signs a message with their private key, the recipient can use the corresponding public key to verify that the message indeed came from the sender and has not been altered in transit.

Here's how it works: the digital signature is created by applying a cryptographic algorithm to the message using the sender's private key. This signature is then sent along with the message. The recipient can then take the received message, use the sender's public key to decrypt the signature, and compare it to the message. If the values match, this confirms that the message was signed by the rightful owner of the private key (the sender) and that the message remains unchanged.

This mechanism provides authentication and integrity, two vital components of secure communication. While the other choices address different aspects of cryptography and security, they do not accurately describe the role of the public key specifically in the context of digital signatures.