Re: [Cfrg] 答复: Re: [saag] New draft: Hashed Password Exchange

"Blumenthal, Uri - 0668 - MITLL" <uri@ll.mit.edu> Wed, 01 February 2012 21:45 UTC

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From: "Blumenthal, Uri - 0668 - MITLL" <uri@ll.mit.edu>
To: "cfrg@irtf.org" <cfrg@irtf.org>
Date: Wed, 1 Feb 2012 16:45:35 -0500
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On 2/1/12 12:11 , "Rose, Greg" <ggr@qualcomm.com> wrote:

>On 2012 Feb 1, at 0:13 , <zhou.sujing@zte.com.cn>
><zhou.sujing@zte.com.cn> wrote:
>> Since passwords are often not too long, and not so random, it is better
>> to hash it before using it as a key in a HMAC.
>
>I'm afraid this is a fallacy. While it will be longer, and will look
>random, there is exactly the same (lack of) entropy in a hashed weak
>password as there is in the original password. It's still vulnerable to
>password search, although with a slightly increased workload due to the
>(single) extra hash invocation.

Concur 100%.