Data integrity guarantees that data sent from one end of a transaction arrives unaltered at
the other end. Even with Secure Shell encryption, the data being sent over the network
could still be vulnerable to someone inserting unwanted data into the data stream (See
Insertion and replay attacks for more details). Secure Shell version 2 (SSH2) uses
Message Authentication Code (MAC) algorithms to greatly improve upon the original
Secure Shell’s (SSH1) simple 32-bit CRC data integrity checking method.