Argon2
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Argon2 is a key derivation function that was selected as the winner of the Password Hashing Competition in July 2015.[1][2] It was designed by Alex Biryukov, Daniel Dinu, and Dmitry Khovratovich from University of Luxembourg.[3] Argon2 is released under a Creative Commons CC0 license, and provides two related versions:
- Argon2d maximizes resistance to GPU cracking attacks.
- Argon2i is optimized to resist side-channel attacks.
Both allow specification by three parameters that control:
- execution time
- memory required
- degree of parallelism
Cryptanalysis[edit]
While there is no public cryptanalysis applicable to Argon2d, there are two published attacks on the Argon2i function.
The first attack shows that it is possible to compute a single-pass Argon2i function using between a quarter and a fifth of the desired space with no time penalty, and compute a multiple-pass Argon2i using only N/e < N/2.71 space with no time penalty.[4] According to the Argon2 authors, this attack vector was fixed in version 1.3.[5]
The second attack shows that Argon2i can be computed by an algorithm which has complexity O(n7/4 log(n)) for all choices of parameters σ (space cost), τ (time cost), and thread-count such that n=σ∗τ.[6] The Argon2 authors claim that this attack is not efficient if Argon2i is used with three or more passes.[5] However, Joël Alwen and Jeremiah Blocki improved the attack and showed that in order for the attack to fail, Argon2i 1.3 needs more than 10 passes over memory.[7]
External links[edit]
References[edit]
- ^ "Password Hashing Competition"
- ^ Jos Wetzels (2016-02-08). "Open Sesame: The Password Hashing Competition and Argon2" (PDF).
- ^ Argon2: the memory-hard function for password hashing and other applications, Alex Biryukov, et al, October 1, 2015
- ^ Henry Corrigan-Gibbs, Dan Boneh, Stuart Schechter (2016-01-14). "Balloon Hashing: Provably Space-Hard Hash Functions with Data-Independent Access Patterns" (PDF).
- ^ a b "[Cfrg] Argon2 v.1.3". www.ietf.org. Retrieved 2016-10-30.
- ^ Joel Alwen, Jeremiah Blocki (2016-02-19). "Efficiently Computing Data-Independent Memory-Hard Functions" (PDF).
- ^ Joël Alwen, Jeremiah Blocki (2016-08-05). "Towards Practical Attacks on Argon2i and Balloon Hashing" (PDF).
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