Answer: D

Message authentication refers to the process of confirming the integrity of received messages on the network. Generally, a hash function, such as MD5 or SHA-1, is used to verify the integrity and authenticity of the text. A digital signature is a pair of public and private keys generated using a public key system (such as RSA). The private key is used to sign the message, and the public key is used to verify the signature of the file, ensuring the non-repudiation of the file. effect.