1) File verification

The verification algorithms we are more familiar with include parity check and CRC check. These two types of checks do not have the ability to resist data tampering. They must It can detect and correct channel errors in data transmission to a certain extent, but it cannot prevent malicious damage to data.

The "digital fingerprint" feature of the MD5Hash algorithm makes it the most widely used file integrity checksum (Checksum) algorithm. Many Unix systems provide commands for calculating md5checksum.

2) Digital signature

The Hash algorithm is also an important part of the modern cryptography system. Since asymmetric algorithms operate slowly, one-way hash functions play an important role in digital signature protocols. Digitally signing a hash value, also known as a "digital digest", can be statistically considered equivalent to digitally signing the file itself. And such an agreement has other advantages.

3) Authentication protocol

The following authentication protocol is also called "challenge--authentication mode: when the transmission channel can be intercepted, but cannot be tampered with Next, this is a simple and safe method.