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Is hash function can be decrypted and reversible?
No, they cannot be decrypted. These functions are not reversible. There is no deterministic algorithm that evaluates the original value for the specific hash. However, if you use a cryptographically secure hash password hashing then you can may still find out what the original value was.
Can encryption be reversed?
Encryption is a reversible transformation. It is useful only when encrypted data (ciphertext) can be reversed back to its original, unencrypted form (plaintext). If not reversible, the encrypted data are considered unreadable and unusable. This reversal process is referred to as decryption.
Why is it not possible to reverse a hash function?
Because the hash function was designed by smart people to be hard to take the reverse of, they can’t easily retrieve your password from it. An attacker’s best bet is a bruteforce attack, where they try a bunch of passwords.
Why are hash functions designed to be one way?
The hash function is designed so it is hard to reverse it and get any answer at all, even a different password with the same hash. In crypto-speak: a hash function vulnerable to a preimage attack is utterly worthless. (The password hashing algorithm above is injective if you have a rule that x < y.)
When to use a slow or fast hash function?
Some hash functions are fast, while others are slow. When it comes to using cryptographic hash functions for password hashing, for example, you’ll want to use a slow hash function rather than a fast one (the slower the better).
How can you tell if a hash algorithm is correct?
So when you try to reverse it (and guess the two inputs in a later stage), the only way to tell if the numbers you are guessing are correct is to work all the way back through the hash algorithm. If you start guessing numbers (in the later stages) wrong, you’ll end up with an inconsistency in the earlier stages (like 2 + 2 = 53).