1994-07-04 - Re: MD5 is 1=>1?

Header Data

From: Roger Bryner <bryner@atlas.chem.utah.edu>
To: Derek Atkins <warlord@MIT.EDU>
Message Hash: 3235272736fc1adc5f44d4b640dcb05fc7dabe28a29caaa2cf46a18919f07505
Message ID: <Pine.3.89.9407041629.A7942-0100000@atlas.chem.utah.edu>
Reply To: <9407042142.AA28845@toxicwaste.media.mit.edu>
UTC Datetime: 1994-07-04 22:18:45 UTC
Raw Date: Mon, 4 Jul 94 15:18:45 PDT

Raw message

From: Roger Bryner <bryner@atlas.chem.utah.edu>
Date: Mon, 4 Jul 94 15:18:45 PDT
To: Derek Atkins <warlord@MIT.EDU>
Subject: Re: MD5 is 1=>1?
In-Reply-To: <9407042142.AA28845@toxicwaste.media.mit.edu>
Message-ID: <Pine.3.89.9407041629.A7942-0100000@atlas.chem.utah.edu>
MIME-Version: 1.0
Content-Type: text/plain

On Mon, 4 Jul 1994, Derek Atkins wrote:
> Does this answer your question?

Again, the only way that MD5 can keep the entropy of a string is for 
every single 128 bit string to map itself onto a unique 128 bit string, 
for if two 128 bit strings produce the same output, then you loose entropy.

The question is, when md5 is restricted to 128 bit values, does it loose 
entropy, and if so how much?  As much as a random mapping?  if so, the 
1024 bit itteration in secure drive HARMS security.