In the preceding section, we saw how to save data securely in Keychain. However, when saving information in Keychain or wherever you want, there is a chance that someone can get this information and that it will be exposed. The best practice when saving any sensitive information in your app or in the server side is for it to be encrypted and, when someone sees the encrypted message, they should not be able to decrypt it again. In this section, we will talk about the cryptographic hash functions.
The cryptographic hash function is a special type of hash function that can be used in cryptography. Using this hash function, you can convert any data (message) to another form of data (digest). These hash functions are meant to be one way and infeasible to be inverted. Let's see the properties of cryptographic hash functions:
The same messages always return the same digest (hash value)
Infeasible to revert the digest and get the message
Infeasible to find two messages with the...