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From "Simon Levermann (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CODEC-245) RegEx for verifying salts in ShaCrypt is incorrect
Date Mon, 12 Feb 2018 18:05:00 GMT

    [ https://issues.apache.org/jira/browse/CODEC-245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16361183#comment-16361183
] 

Simon Levermann commented on CODEC-245:
---------------------------------------

Though I suppose it's still *somewhat* incorrect: Apparently, *all bytes* are valid salts,
not just base64 characters. For example, invoking the libc crypt function like this:

 
{code:java}
char *foo = crypt("asdfasdf", "$6$mounds=1000$asdf$");
{code}
 
results in the following hash:
{code:java}
$6$mounds=1000$A9qEzceIj1cqGxb4w8WdBvHHotUYOmx.xnedWJRwQQJCZCHKpSHX4qwcY9DIvXN.ggWMhKRW4pE93oGgPOOBy0
{code}
That is: "mounds=1000" is the literal salt here, and the actually supplied salt, "asdf" is
discarded. Apparently the specification does NOT mandate that salts must be B64-encoded. It
seems like any bytes (even non-printable characters) are valid for salts, but only ever the
first 16 bytes are used. Thoughts on how to continue here?

> RegEx for verifying salts in ShaCrypt is incorrect
> --------------------------------------------------
>
>                 Key: CODEC-245
>                 URL: https://issues.apache.org/jira/browse/CODEC-245
>             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
hashing:
> {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
like
>  
> {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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