[jboss-jira] [JBoss JIRA] (ELY-779) Iteration count transformation: BCrypt

[David Lloyd (JIRA)]

    [ https://issues.jboss.org/browse/ELY-779?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13326710#comment-13326710 ] 

David Lloyd commented on ELY-779:
---------------------------------

One thing we need to talk about - again - is that BCrypt uses a "cost" parameter which is the log2 of the actual iteration count.  I think that we probably would want to at least consider using a real iteration count algorithm parameter to represent the actual count, even though the values have an unusual domain of validity (‹2⁴, ..., 2³¹›, which can be verified by the simple expression {{Integer.bitCount(n) == 1}}).

One challenge of the cost parameter in the implementation is that to raise the cost to the next valid value, you have to add 2ⁿ - 2ⁿ⁻¹ iterations which is hard to fit in with the scheme.  We'd probably have to convert to iterations/rounds internally anyway so we can calculate the difference and apply the additional rounds.

> Iteration count transformation: BCrypt
> --------------------------------------
>
>                 Key: ELY-779
>                 URL: https://issues.jboss.org/browse/ELY-779
>             Project: WildFly Elytron
>          Issue Type: Sub-task
>            Reporter: David Lloyd
>




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