[WEB SECURITY] FW: Password Manager with Fingerprint Verification

Thomas Ptacek thomas at matasano.com
Thu Jun 9 14:47:17 EDT 2011


I don't understand what "static bcrypt" is.

The default work factor for bcrypt (in most libraries, this number is "10") is so much more effective than any other password hashing strategy that it is unnecessary to recommend an alternative.

Every article about bcrypt makes a point of saying the work factor is tunable. That is, after all, the point of bcrypt.

Dialing up the work factor imposes application costs. bcrypt with a work factor of 12 is probably too slow for any popular web application. Again: this cost/benefit tradeoff is the point of bcrypt, not a liability. But it's also a reason why you don't bother telling people to noodle around changing their cost factors.

"Secret salt" schemes are flawed, universally. If you are depending on a bare cryptographic hash with a "salt" for your security, without a vetted iterating/stretching construct, you are in fact introducing vulnerabilities into your applications. We would tend to document any such schemes as vulnerabilities in assessments; that's how clear this issue is. Don't use salted hashes to store passwords. They are inadequate.

On Jun 9, 2011, at 1:39 PM, James Manico wrote:

> Using bcrypt in a static way is a poor idea. You must also increase the work factor over time. The article below fails to recommend a specific work factor nor does it suggest that the work factor needs to increase over time.
> 
> Bcrypt is a good solution for password storage, don't get me wrong, but it's not the only solution.
> 
> Salting can also lower dictionary attack risks in some situations if you isolate the salt from the hash.
> 
> Respectfully,
> Jim Manico
> 
> On Jun 9, 2011, at 19:31, Thomas Ptacek <thomas at matasano.com> wrote:
> 
>> You're right; they can only use bcrypt if they're on Rails, Python, PHP, Perl, .NET, Java, C/C++, or Erlang.
>> 
>> Iterating SHA256 correctly is a little trickier than just repeatedly rehashing (see: RFC2898 for PBKDF2), but does work.
>> 
>> In working with and talking to over a hundred startup web developers, I've learned that when you leave password hashing open to implementation (for instance, by rolling your own "stretched" SHA256), you end up with people who use secret salts. It's better --- it's just better --- to use bcrypt. 
>> 
>> On Jun 9, 2011, at 1:27 PM, James Manico wrote:
>> 
>>> Not everyone had access to bcrypt. Iterating the hash thousands of times mitigates the concern in the paper below. This hash iteration count is basically the same thing as bcrypts work factor and just like using bcrypt this work factor will need to be increased over time.
>>> 
>>> Hash iteration count was recommended to be 1000 in the year 2000 and should be doubled every three years to be in line with bcrypts work factor recommendations.
>>> 
>>> Cheers from AppSecEU in Dublin.
>>> 
>>> Jim Manico
>>> 
>>> On Jun 9, 2011, at 17:12, Thomas Ptacek <thomas at matasano.com> wrote:
>>> 
>>>> http://codahale.com/how-to-safely-store-a-password/
>>>> 
>>>> Just read this article and do exactly what it says.
>>>> 
>>>> On Jun 8, 2011, at 6:34 PM, Vikneswaran Kunasegaran wrote:
>>>> 
>>>>> Hi Gautham..
>>>>>  
>>>>> So in your email below are you stating that without encryption, salting and hashing alone would be secured and difficult to crack by unauthorised people? I was just thinking too much on how to make my databse secure maybe thats why I got into this. Sorry though hehe. So, in your opinion, what would be your advise if I wanted to salt this password for a 1000 times and then hash it as this was a comment from another person who replied my email. Is it okay or the suggestion you made is secured enough. Kindly awaiting your reply on this. And thank you very much for replying me Mr Gautham. Really appreciate it. 
>>>>>  
>>>>> Have a nice day. 
>>>>>  
>>>>> Date: Tue, 7 Jun 2011 16:15:30 -0700
>>>>> Subject: Re: Password Manager with Fingerprint Verification
>>>>> From: itsecanalyst at gmail.com
>>>>> To: rmc_0306 at hotmail.com
>>>>> CC: security-basics at securityfocus.com; websecurity at webappsec.org
>>>>> 
>>>>> I am still trying to get my understanding clear here. why would you want to (salted+hash) and then encrypt it. Is just getting a hash not enough, you can do salted+sha256 and you should be good.
>>>>> 
>>>>> if you want a clear text password, then you might want to encrypt it, however it all depends what is the final use of these credentials. There are more controls that you would need to get in place if you want to encrypt-decrypt and then key management is a big issue that you need to think.
>>>>> 
>>>>> G
>>>>> 
>>>>> On Tue, May 31, 2011 at 6:01 PM, <rmc_0306 at hotmail.com> wrote:
>>>>> Hello Friends.
>>>>> 
>>>>> Im a final year student for COmputer Security / Forensic. Im planning to do a project which requires me to do encryption and decryption. My possible choice of language would be VB.Net. I was wondering if wad is running in my mind can be executed. Well, I would make a application where a part of it wil be promting the guest to register and I wanted to store the password in the database. I did some research and came across Salting and Hashing. I was wondering if is it possible to get the password which the user enters, salt it, hash it and encrypt it before I store in the database. If so, what is the best secured strong encryption can I use in VB.net. Because through out the research I have done, i have sen RInjdael as the most fav encryption algo which alot of programmers using. JUst a though on this. Kindly advise me. Thank you for your generous help and for reading query.
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>>>> 
>>>> 
>>>> ---
>>>> Thomas Ptacek // matasano security // founder, product manager
>>>> reach me direct: 888-677-0666 x7805
>>>> 
>>>> "The truth will set you free. But not until it is finished with you."
>>>> 
>>>> 
>>>> 
>>>> 
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>> 
>> 
>> ---
>> Thomas Ptacek // matasano security // founder, product manager
>> reach me direct: 888-677-0666 x7805
>> 
>> "The truth will set you free. But not until it is finished with you."
>> 
>> 
>> 
>> 


---
Thomas Ptacek // matasano security // founder, product manager
reach me direct: 888-677-0666 x7805

"The truth will set you free. But not until it is finished with you."




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