Balloon hashing is a
key derivation function
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 cr ...
presenting proven memory-hard password-hashing and modern design. It was created by
Dan Boneh
Dan Boneh (; ) is an Israeli–American professor in applied cryptography and computer security at Stanford University.
In 2016, Boneh was elected a member of the National Academy of Engineering for contributions to the theory and practice of cr ...
, Henry Corrigan-Gibbs (both at
Stanford University
Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth ...
) and Stuart Schechter (
Microsoft Research
Microsoft Research (MSR) is the research subsidiary of Microsoft. It was created in 1991 by Richard Rashid, Bill Gates and Nathan Myhrvold with the intent to advance state-of-the-art computing and solve difficult world problems through technologi ...
) in 2016.
It is a recommended function in
NIST password guidelines.
NIST SP800-63B Section 5.1.1.2
/ref>
The authors claim that Balloon:
* has ''proven'' memory-hardness properties,
* is built from standard primitives: it can use any standard non-space-hard cryptographic hash function
A cryptographic hash function (CHF) is a hash algorithm (a map (mathematics), map of an arbitrary binary string to a binary string with a fixed size of n bits) that has special properties desirable for a cryptography, cryptographic application: ...
as a sub-algorithm (e.g., SHA-3
SHA-3 (Secure Hash Algorithm 3) is the latest member of the Secure Hash Algorithm family of standards, released by NIST on August 5, 2015. Although part of the same series of standards, SHA-3 is internally different from the MD5-like stru ...
, SHA-512
SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression ...
),
* is resistant to side-channel attack
In computer security, a side-channel attack is a type of security exploit that leverages information inadvertently leaked by a system—such as timing, power consumption, or electromagnetic or acoustic emissions—to gain unauthorized access to ...
s: the memory access pattern is independent of the data to be hashed,
* is easy to implement and matches the performance of similar algorithms.
Balloon is compared by its authors with Argon2
Argon2 is a key derivation function that was selected as the winner of the 2015 Password Hashing Competition. It was designed by Alex Biryukov, Daniel Dinu, and Dmitry Khovratovich from the University of Luxembourg. The reference implementation o ...
, a similarly performing algorithm.
Algorithm
There are three steps in the algorithm:pseudorandom
A pseudorandom sequence of numbers is one that appears to be statistically random, despite having been produced by a completely deterministic and repeatable process. Pseudorandom number generators are often used in computer programming, as tradi ...
byte sequence derived from the password and salt repeatedly hashed.
# Mixing, where the bytes in the buffer are mixed ''time_cost'' number of times.
# Output, where a portion of the buffer is taken as the hashing result.
References
Further reading
*
*
External links
Research prototype code on Github
Python implementation
Rust implementation
{{Cryptography navbox , hash
category:Key derivation functions