Читать книгу Mastering Linux System Administration - Richard Blum - Страница 82

Hashing uses a one‐way mathematical algorithm to create a fixed‐length hash, which is basically a series of letters and numbers. A hash is also called a message digest, a hash value, a fingerprint, a signature, or cipher text. One cool thing about hash values is that certain hashing algorithms produce the same hash value for files that are the same. Thus, you can take a file with a picture in it and copy it to another location across the network. If we use hashing to produce a hash value for the original picture file and for the copied picture file and those two hash values match, we know that the picture was not corrupted when it was copied to the new location.

While you work your way through the following exercise, you may find you have a corrupted CentOS ISO image file. If this is the case, you'll need to re‐download the file and check it via hashing again.