What Is a Hash Function — Security+ SY0-701 Domain 1.4 #sy0701 #securityplus #comptiasecurityplus

Added: 2026-05-06

[00:00:00]Hashing is something you are going to  definitely need to understand for the Security Plus exam. A hash function takes  any input, a password, a file, a message, and converts it into a fixed length string  of characters called a hash. Remember fixed length. That output is also called a message  digest or a fingerprint. Three things make hashing what it is. It's one way. You cannot  reverse a hash back to the original input.

[00:00:29]It's deterministic. So the same input always  produces the same output and it is sensitive.

[00:00:37]Uh change even one character in the input and the  entire hash output looks completely different.

[00:00:45]That last property is called the avalanche effect.  It's why hashing is used for data integrity. If someone tampers with a file, the hash will not  match. The most important hash algorithms to know for the exam are MD5 128-bit condensed and  broken Sha-1 which is also deprecated and Sha-256 which is the current standard. And know that  hashing is not encryption. There's no key. You can't get the original data back like mentioned.  That distinction is going to show up on your exam.