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From "Simon Levermann (JIRA)" <>
Subject [jira] [Commented] (CODEC-245) RegEx for verifying salts in ShaCrypt is incorrect
Date Mon, 12 Feb 2018 18:00:03 GMT


Simon Levermann commented on CODEC-245:

Well it turns out it was I who was wrong. The spec for shacrypt was apparently written with
the following thought in mind: "Invalid inputs do not exist. Every input is valid *no matter
what*". So, apparently, this behaviour, despite being HIGHLY confusing and obviously insane,
is correct. Not quite sure what to do about this.

> RegEx for verifying salts in ShaCrypt is incorrect
> --------------------------------------------------
>                 Key: CODEC-245
>                 URL:
>             Project: Commons Codec
>          Issue Type: Bug
>    Affects Versions: 1.11
>            Reporter: Simon Levermann
>            Priority: Major
> The regex/code that extracts the salt from a given salt string in Sha2Crypt treats some
invalid salt formats as valid:
> {code:java}
> ^\$([56])\$(rounds=(\d+)\$)?([\.\/a-zA-Z0-9]{1,16}).*
> {code}
> The code then goes on to use capture group 3 (the round count) to determine how many
rounds are used, and capture group 4 (the actual salt) to use as salt data.
> However, for an input that contains an invalid salt specification like this:
> {code:java}
> $5$notrounds=1000$asdfasdf
> {code}
> This string is treated as valid. The operation then uses "notrounds" as the salt for
> {code:java}
> System.out.println(Sha2Crypt.sha256Crypt(new byte[100], "$5$notrounds=1000$asdfasdf"));
> {code}
> The above code prints
> {code:java}
> $5$notrounds$aAEx6EzUBfc.aIIeiItVjUREbj/ar4xlb/qcMxD90NA
> {code}
> This code should probably throw an exception. Additionally, other invalid salt strings
> {code:java}
> $6$rounds=1000$äöüäöü
> {code}
> Result in hashes like:
> {code:java}
> $5$rounds$ZIRdMgi25kK5Zmi1whKjcnFN/Pe8QCAOlTmxMfwAoq5
> {code}
> Completely ignoring the rounds parameter, and using the literal string "rounds" as the
salt for hashing.

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