In the context of digital signatures, what does RSA specifically do?

RSA, which stands for Rivest-Shamir-Adleman, is primarily known for its role in public key cryptography, specifically in the process of digital signatures. In this context, RSA operates by enabling the creation of a digital signature for a given piece of data or message. This process involves first computing a hash or message digest of the data, which effectively reduces the data to a fixed-size string that uniquely corresponds to the original message.

After this hash is generated, RSA utilizes its asymmetric key mechanism to encrypt the hash with the sender's private key. This encrypted hash then serves as the digital signature that accompanies the original message. When the recipient receives the message, they can decrypt the signature using the sender's public key to verify the authenticity of the signature. This ensures that the message has not been altered and verifies the identity of the sender.

While hashing does form a crucial part of this process, RSA specifically deals with the application of encryption to the hash for the purpose of signing, making the connection between the hash and the sender's identity. Therefore, the role of RSA in the context of digital signatures is accurately represented in the option related to computing a message digest, as it is a necessary precursor to the signing process that RSA facilitates.