GSoC 2019 Report: Incorporating the memory-hard Argon2 hashing scheme into NetBSD


July 09, 2019 posted by Kamil Rytarowski

This report was prepared by Jason High as a part of Google Summer of Code 2019

Argon2 is a modern memory-hard hashing scheme designed by Biryukov et al.[1] Compared to currently supported hashing algorithms in NetBSD, memory-hard Argon2 provides improved resistance against Time Memory Trade-off (TMTO) and side-channel attacks. In our project, we are working to incorporate Argon2 into the local password management framework of NetBSD.

Phase 1 goals and work completed

Phase 1 of the project focused on incorporating the Argon2 reference implementation into NetBSD. As such, we focused on building the associated libraries and integrating the functionality into the existing password management framework. Our initial phase 1 goals were as follows

  • Integrate Argon2 reference code into the existing build framework
  • Support automated building and installation of argon2 binary and libraries
  • Extend the existing password management framework to support Argon2 encoding

Towards these goals, we have added the Argon2 reference code into the external source tree and created the necessary build scripts. This work allows us to successfully add Argon2 into our system by adding MKARGON2=yes to /usr/share/mk/bsd.own.mk. After successfully building and installation, we have the following

/usr/bin/argon2
/lib/libargon2.so     
/lib/libargon2.so.1   
/lib/libargon2.so.1.0

We then extended the functionality of pwhash(1) and libcrypt(3) to support Argon2 encoding. Currently we support all three Argon2 variants, although not all variants are recommended (see [1][2]). We support the following standard parameters: execution time (t), memory utiltized (m), and degree of parallelism (p). Salt length is currently fixed at the recommended 16 bytes.[1]

With our phase 1 goals successfully completed, we have the following functionality available. The argon2(1) binary allows us to easily validate parameters and encodings

m2# echo -n password|argon2 somesalt -id -p 3 -m 8
Type:           Argon2id
Iterations:     3
Memory:         256 KiB
Parallelism:    3
Hash:           97f773f68715d27272490d3d2e74a2a9b06a5bca759b71eab7c02be8a453bfb9
Encoded:        $argon2id$v=19$m=256,t=3,p=3$c29tZXNhbHQ$l/dz9ocV0nJySQ09LnSiqbBqW8p1m3Hqt8Ar6KRTv7k
0.000 seconds
Verification ok
Argon2 support has been added to pwhash(1) using the -A flag, using the form -A variant[params], where variant is one of the following: argon2i, argon2d, or argon2id. [params] is a comma-delimited list of the following: p=%d, m=%d, or t=%d (see man pwhash(1)). For example, to create an encoding of 'password' using the argon2id variant, we may execute the following
m2# pwhash -A argon2id password
$argon2id$v=19$m=4096,t=3,p=1$.SJJCiU575MDnA8s$+pjT4JsF2eLNQuLPEyhRA5LCFGQWAKsksIPl5ewTWNY
To encode 'password' using the argon2id variant with explicit specification for both parallelism and memory, we execute
m2# pwhash -Aargon2id,p=3,m=8192  password 
$argon2id$v=19$m=8192,t=3,p=3$gGs/lLnXIESuSl4H$fGuqUn2PeNeoCFqV3ASvNdkXLZ2A1wZTb2s7LTe4SE0
We support local password hashing using passwd.conf(5). We accept the same parameters as pwhash(1). For example
m1# grep -A1 testuser /etc/passwd.conf 
testuser:
        localcipher = argon2i,t=6,m=4096,p=1
With the above configuration in place, we are able to support standard password management. For example
m1# id testuser 
uid=1001(testuser) gid=100(users) groups=100(users)

m1# grep testuser /etc/master.passwd                                                                                          
testuser:$argon2i$v=19$m=4096,t=6,p=1$MpbO25MF2m4Y/aQT$9STuNmQLMSgYBVoQiXyDLGcb+DSHysJOQh1spI6qEuE:1001:100::0:0::/home/testuser:/sbin/nologin

m1# passwd testuser
Changing password for testuser.
New Password:
Retype New Password:

m1# grep testuser /etc/master.passwd  
testuser:$argon2i$v=19$m=4096,t=6,p=1$PDd65qr6JU0Pfnpr$8YOMYcwINuKHoxIV8Q0FJHG+RP82xtmAuGep26brilU:1001:100::0:0::/home/testuser:/sbin/nologin

Plans for next phase

Phase 2 will focus on code cleanup and incorporation of any improvements suggested during review. We are also extending our ATF test-set and will begin our performance evaluation. Primary deliverables for phase 2 will be a performance evaluation.

Summary

We have successfully integrated Argon2 into NetBSD using the native build framework. We have extended existing functionality to support local password management using Argon2 encoding. Moving forward in phase 2, we will work on cleanup, validation, and performance evaluation.

References

[1] Biryukov, Alex, Daniel Dinu, and Dmitry Khovratovich. "Argon2: new generation of memory-hard functions for password hashing and other applications." 2016 IEEE European Symposium on Security and Privacy (EuroS&P). IEEE, 2016.
[2] Alwen, Joël, and Jeremiah Blocki. "Towards practical attacks on argon2i and balloon hashing." 2017 IEEE European Symposium on Security and Privacy (EuroS&P). IEEE, 2017. [0 comments]

 



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