Cryptographic Hashing in simple words

Hashing Provides Data Integrity

Let’s take an example and make it simple to understand the hashing function. You have an account on Twitter and you insert the user id and password to authenticate. Twitter already has your password saved into their database. So when you present the password at login, it checks your identity and if it’s correct, it allows you to log in to the account. An important point to note here is that the password stored in the database is not saved as a plain-text. It is actually the hash value or message digest of the password (provided by the user) and a salt (random bits added by Twitter). When the user-supplied the password, its hash value is compared with the value stored in the password database. If it matches, the user is allowed to get in otherwise access is denied. Adding salt prevents the database from a rainbow table-type attack and I have explained this later in the story.

The hashing function takes any length of the message, processes through the choice of algorithm, and it produces a fixed length of the message digest. This is a one-way function, meaning it is irreversible. There is no key in the hashing. Compare the message digest at the receiving end to ensure the message has not been modified.

In the below example, Aladdin wants to send a file of his wish list to Jasmine before he puts it…