A small piece of information generated by a specific algorithm, which is used to check the integrity of a message and for authentication. It can be used to check whether the message content has been changed during delivery, regardless of whether the reason for the change is an accident or a deliberate attack. At the same time, it can be used as the authentication of the source of the message and confirm the source of the message.
Extended data:
Unofficially, message authentication codes consist of three algorithms:
1. The key generation algorithm randomly and evenly selects keys from the key space.
2. Given the key and signature algorithm of the message, the tag is effectively returned.
3. The authentication algorithm effectively verifies the authenticity of the message with the given key and tag. That is to say, when the message and label have not been tampered with or forged, the return is accepted, otherwise the return is refused.