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Date: Tue, 1 Jan 2013 21:56:06 +0100
From: Frank Dittrich <>
Subject: Re: A few questions regarding the newly added BLAKE2 format

On 01/01/2013 09:12 PM, magnum wrote:
> My personal opinion is that we should definitely accept untagged hashes, of course provided that the length and charset is correct. We have this very good feature where John tells us what formats could be using the hash. To make an input file automatically pick a certain format, add tags in the file with a trivial sed one-liner. Or just supply the --format option. On a related note, I think we should always add tags to john.pot (and this format do) unless the hash format is odd enough to be easily recognized even with future in mind. I'd really like to hear other's opinions too, including but not limited to Solar. And the john-users crowd too btw.

My main concern here is that, especially with plugged-in-formats, you
never know how the sequence of formats will be changes, so that hashes
which now are treated as raw-sha512, will tomorrow be treated as
something different (e.g., BLAKE2).

> Second, the dynamic format currently does not seem to accept *any* untagged hash until you set DynamicAlwaysUseRawHashes=Y in john.conf. But if you do, dynamic seem to get too greedy, even accepting this 128 character hash as raw-md5! I am not quite sure how it is supposed to work: Maybe the current behavior is on purpose and it would only use the first 32 characters of that 128 char hash for eg. raw-md5? If that's it, I would prefer dynamic to accept it as dynamic_80 with that option turned off. But that is up to Jim to decide, I know dynamic is very complicated.

The dynamic formats also accept these hashes when using
--format=dynamic_0 (or dynamic_2, dynamic_3, dynamic_19, ...).

IMHO, only raw hashes with the correct length should be treated by
dynamic formats.
But may be Jim can explain why this is actually a feature, not a bug.


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