The cryptographic data verification method is: use checksum, because checksum can solve the problems of data verification storage. And the checksum is a definite value derived from the message data and can be transmitted individually, which means that the checksum of a given message is always the same.

The recipient of the checksum message can generate a checksum from the message. If the generated checksum matches the checksum of the sent message, the sent message will not be tampered with.

It should be noted that if the medium for obtaining the checksum is unreliable, both the information and the checksum may be tampered with by a middleman. It is usually better to digitally sign the checksum. The digital signature proves the identity of the sender of the checksum.

What makes a good checksum:

There are many types of checksums, but the best checksum is usually a cryptographic hash function. The hash function can generate a good checksum and verify the integrity of the data. The following are its properties.

Deterministic: The hash value of the same information is always the same, and there is no randomness.

Fast: no need to use unnecessary resources to calculate checksums (KDF is an inefficient checksum).

Almost no overlap: The possibility of two different pieces of information generating the same checksum is almost zero.

Simple: The result of the hash (aka "digest") should be short, without wasting a lot of data.