Description

dgolombek

opened on Nov 5, 2013

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Running the following code in MRI 1.9.3 and REE 1.8.7 returns true, while running in JRuby (1.6.7.2, 1.7.3, and 1.7.6, in both 1.8 and 1.9 modes) returns false

require 'rubygems'
require 'bcrypt'
require 'base64'
b64h = "BqvyJXQvnL3CKVd6pAv25giyYNEGXg4k5UOwkTeYXZo=\n"
password = "$2a$12$BaVII7NCCtTxF4BKdjPy2.IkvEG4X4/CRhDvmenQKm2r/6pIoW..q"
BCrypt::Password.new(password) == Base64.decode64(b64h)

I've run all the testcases from http://www.mindrot.org/projects/jBCrypt/ and they produce the same results on MRI and JRuby, so this isn't an across-the-board incompatibility, but something about password makes it unhappy. I haven't yet run this in other Bcrypt impls in other languages to see what they return.

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1. tjschuck commented on Nov 5, 2013

   

   tjschuck

   on Nov 5, 2013

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   Is your base64 encoding/decoding necessary to make this work? Does this give the same behavior?

   plaintext = "%t/)Wz`^$C7]'"
   hashed = BCrypt::Password.create(plaintext)
   BCrypt::Password.new(hashed) == plaintext  # => true
2. dgolombek commented on Nov 5, 2013

   

   dgolombek

   on Nov 5, 2013

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   Yes, the Base64 encoding appears to be related -- that code works in both
   JRuby and MRI. The value that is Base64 encoded came from a HMAC, the
   submitted code is a simplification of some code derived from
   https://github.com/fwenzel/django-sha2.

   Thanks
   Dave

   On Tue, Nov 5, 2013 at 3:56 PM, T.J. Schuck [email protected]:

   Is your base64 encoding/decoding necessary to make this work? Does this
   give the same behavior?

   plaintext = "%t/)Wz`^$C7]'"hashed = BCrypt::Password.create(plaintext)BCrypt::Password.new(hashed) == plaintext # => true

   —
   Reply to this email directly or view it on GitHubhttps://github.com//issues/82#issuecomment-27811478
   .
3. tjschuck commented on Nov 5, 2013

   

   tjschuck

   on Nov 5, 2013

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   Yep -- took me a minute to install JRuby, but the above code (without the base64ing) definitely works on JRuby 1.7.3, and confirmed that the base64 version does not.
4. Oscil8 commented on Nov 5, 2013

   

   Oscil8

   on Nov 5, 2013

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   For another failing test case, from the BCrypt test strings at: http://cvsweb.openwall.com/cgi/cvsweb.cgi/Owl/packages/john/john/src/BF_fmt.c?rev=HEAD

   BCrypt::Password.new("$2a$05$/OK.fbVrR/bpIqNJ5ianF.swQOIzjOiJ9GHEPuhEkvqrUyvWhEMx6") == "\xaa"*72
   

   returns true on MRI, and false on JRuby (1.7.4 in my case)
5. reedloden commented on Mar 11, 2014

   

   reedloden

   on Mar 11, 2014

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   I wonder if the change in jBCrypt 0.3 (http://mindrot.org/files/jBCrypt/internat.adv -- 92c8e4e) affects this at all...

   @djmdjm, any ideas?
6. zofrex commented on Jul 23, 2014

   

   zofrex

   on Jul 23, 2014

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   I don't fully understand this issue... does it only come into effect if Base64 is involved?
   What I'm worried about: I have a bunch of hashes being created using this library running under JRuby. I'm going to be migrating to MRI later this year. Is there a chance some of my users will be locked out if I migrate due to this bug?
7. dgolombek commented on Jul 23, 2014

   

   dgolombek

   on Jul 23, 2014

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   Base64 itself is unrelated, but it may have to do with UTF-8 or other
   non-ascii characters in the source material.

   Yes, the transition from JRuby to/from MRI is exactly the scenario that I
   was testing when I encountered this issue.

   I haven't yet tested Reed's suggestion around the jBCrypt 0.3 fix, it
   certainly does look potentially relevant.

   Thanks
   Dave

   On Wed, Jul 23, 2014 at 1:43 PM, zofrex [email protected] wrote:

   I don't fully understand this issue... does it only come into effect if
   Base64 is involved?
   What I'm worried about: I have a bunch of hashes being created using this
   library running under JRuby. I'm going to be migrating to MRI later this
   year. Is there a chance some of my users will be locked out if I migrate
   due to this bug?

   —
   Reply to this email directly or view it on GitHub
   #82 (comment).
8. zofrex commented on Jul 30, 2014

   

   zofrex

   on Jul 30, 2014

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   What is the probability of an incorrect hash being generated? For every say, million hashes generated by this library in JRuby, how many should we expect to be incorrect when transitioning to MRI?
9. Oscil8 commented on Jan 18, 2015

   

   Oscil8

   on Jan 18, 2015

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   Have done a bit of work on this recently. There are two key issues: a) when using 8-bit characters, the JRuby -> Java conversion and the jBCrypt use of .getBytes("UTF-8") ensure inconsistent results compared with the native implementation; b) the native implementation can't handle strings containing "\0" null values because it assumes null-terminated strings, whereas jBCrypt doesn't pay attention to those.

   Long story short, make sure your input to the bcrypt is all ASCII values between 1 and 127 (7-bit clean, no zeroes) and I believe you'll be safe.
10. reedloden commented on Mar 13, 2015

    

    reedloden

    on Mar 13, 2015

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    Somewhat related, especially to \0... http://blog.ircmaxell.com/2015/03/security-issue-combining-bcrypt-with.html

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