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https://issues.apache.org/jira/browse/NIFI-1257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15135614#comment-15135614
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ASF subversion and git services commented on NIFI-1257:
-------------------------------------------------------

Commit b4073796708193a2d0c8742455bf1ac612b4cafe in nifi's branch 
refs/heads/master from [~alopresto]
[ https://git-wip-us.apache.org/repos/asf?p=nifi.git;h=b407379 ]

NIFI-1257 Resolved legacy compatibility issue with NiFi legacy KDF salt length 
dependent on cipher block size.

Replaced screenshot for NiFiLegacy salt encoding.
Added description of legacy salt length determination in admin guide.
Added logic for NiFiLegacyCipherProvider to generate and validate salts of the 
length determined by the cipher block size.
Changed EncryptContent to default to Bcrypt KDF.

Signed-off-by: Aldrin Piri <[email protected]>


> Provide additional KDFs for EncryptContent
> ------------------------------------------
>
>                 Key: NIFI-1257
>                 URL: https://issues.apache.org/jira/browse/NIFI-1257
>             Project: Apache NiFi
>          Issue Type: Improvement
>          Components: Core Framework
>    Affects Versions: 0.4.0
>            Reporter: Andy LoPresto
>            Assignee: Andy LoPresto
>            Priority: Critical
>              Labels: encryption, security
>             Fix For: 0.5.0
>
>         Attachments: 1257_salt_patch.diff
>
>
> Currently, the two key derivation functions (KDF) supported are NiFi Legacy 
> (1000 iterations of MD5 digest over a password and optional salt) and OpenSSL 
> PKCS#5 v1.5 (a single iteration of MD5 digest over a password and optional 
> salt). 
> Both of these are very weak -- they use a deprecated cryptographic hash 
> function (CHF) with known weakness and susceptibility to collisions (with 
> demonstrated attacks) and a non-configurable and tightly coupled iteration 
> count to derive the key and IV. 
> Current best practice KDFs (with work factor recommendations) are as follows:
> * PBKDF2 with variable hash function (SHA1, SHA256, SHA384, SHA512, or 
> ideally HMAC variants of these functions) and variable iteration count (in 
> the 10k - 1M range). 
> * bcrypt with work factor of 12 - 16
> * scrypt with work factor of (2^14 - 2^20, 8, 1)
> The salt and iteration count should be stored alongside the hashed record 
> (bcrypt handles this natively). 
> Notes:
> * http://wildlyinaccurate.com/bcrypt-choosing-a-work-factor/
> * http://blog.ircmaxell.com/2012/12/seven-ways-to-screw-up-bcrypt.html
> * 
> http://security.stackexchange.com/questions/17207/recommended-of-rounds-for-bcrypt
> * 
> http://security.stackexchange.com/questions/3959/recommended-of-iterations-when-using-pkbdf2-sha256/3993#3993
> * 
> http://security.stackexchange.com/questions/4781/do-any-security-experts-recommend-bcrypt-for-password-storage/6415
>  
> * 
> http://web.archive.org/web/20130407190430/http://chargen.matasano.com/chargen/2007/9/7/enough-with-the-rainbow-tables-what-you-need-to-know-about-s.html
> * 
> https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2015/march/enough-with-the-salts-updates-on-secure-password-schemes/
> * http://www.tarsnap.com/scrypt.html
> * http://www.tarsnap.com/scrypt/scrypt.pdf



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