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Date: Sat, 22 Dec 2012 14:13:50 +0100
From: Sebastian Krajenski <>
Subject: Re: gpg2john -> false positive -> how to exclude?

Hello again, many thanks for your efforts. Besides a real fix for this, 
how were you able to let john /not/ to exit
after one false positive is found?

Thanks in advance.

On 18.12.2012 01:11, magnum wrote:
> On 17 Dec, 2012, at 4:01 , Dhiru Kholia<>  wrote:
>> On Monday 17 December 2012 04:39 AM,  wrote:
>>> the converted gpg2john hash is:
>>> secring.gpg:$gpg$*17*24*1024*2fd8c6834db06ddfe073fd944b6bd8dbd268163e6374ef6f*3*255*2*3*8*bf07a2f4faafa916*65536*6c7784ea65895667
>>> the one false positive i got is in clear-text: bortaloo
>>> (which is not my phrase | and thus does not work for unlocking)
>>> If you need the real secring.pgp and a ciphertext file, private email would be great :)
>> Hi Seb,
>> This false positive is unexpected. Please send the real secring.pgp file (private email is fine).
>> I can check if other softwares give "bortaloo" as the password too.
> I tried adding FMT_NOT_EXACT and ran it for a couple hours with a toy GPU. It found 10 "valid" guesses in 2h, 18 minutes (roughly 200 million candidates tried):
> bortaloo
> dyss
> ksm38b
> mrh1644
> bh994co
> g5xck
> 24279720
> w0wory
> lt5ntyb
> 25318696
> This "hash" type use the simplest checksumming that will give one false positive out of 64K tries. I notice the 'datalen' is short compared to the test vectors - apparently short enough to emit a false positive from the BN_bin2bn() function once out of about 300 tries. When both these false positives occur for one same candidate, it will result in a false guess (about once in 20 million tries).
> magnum

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