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In cryptanalysis and computer security, password cracking is the process of guessing passwords [1] protecting a computer system.A common approach (brute-force attack) is to repeatedly try guesses for the password and to check them against an available cryptographic hash of the password. [2]
A pepper adds security to a database of salts and hashes because unless the attacker is able to obtain the pepper, cracking even a single hash is intractable, no matter how weak the original password. Even with a list of (salt, hash) pairs, an attacker must also guess the secret pepper in order to find the password which produces the hash.
For example, bcrypt cannot be used to derive a 512-bit key from a password. At the same time, algorithms like pbkdf2, scrypt, and argon2 are password-based key derivation functions - where the output is then used for the purpose of password hashing rather than just key derivation. Password hashing generally needs to complete < 1000 ms.
A brute-force attack is a cryptanalytic attack that can, in theory, be used to attempt to decrypt any encrypted data (except for data encrypted in an information-theoretically secure manner). [1] Such an attack might be used when it is not possible to take advantage of other weaknesses in an encryption system (if any exist) that would make the ...
To learn a password from a hash is to find a string which, when input into the hash function, creates that same hash. This is the same as inverting the hash function. Though brute-force attacks (e.g. dictionary attacks ) may be used to try to invert a hash function, they can become infeasible when the set of possible passwords is large enough.
The salt and hash are then stored in the database. To later test if a password a user enters is correct, the same process can be performed on it (appending that user's salt to the password and calculating the resultant hash): if the result does not match the stored hash, it could not have been the correct password that was entered.
Example of a Key Derivation Function chain as used in the Signal Protocol.The output of one KDF function is the input to the next KDF function in the chain. In cryptography, a key derivation function (KDF) is a cryptographic algorithm that derives one or more secret keys from a secret value such as a master key, a password, or a passphrase using a pseudorandom function (which typically uses a ...
In cryptography, scrypt (pronounced "ess crypt" [1]) is a password-based key derivation function created by Colin Percival in March 2009, originally for the Tarsnap online backup service. [ 2 ] [ 3 ] The algorithm was specifically designed to make it costly to perform large-scale custom hardware attacks by requiring large amounts of memory.