Re: yahoo mail login security

[Andrew van der Stock <vanderaj () greebo net>]

Several reasons:

1. MD5 does protect the password... as long as it is salted  
correctly. Unsalted MD5 hashes are trivially breakable using rainbow  
attacks, and are unsuitable for most uses (despite heavy usage by  
many programs in exactly this fashion).

2. Replay attacks on public networks. Capturing the form submission  
(trivial without SSL) would allow an attacker to replay the  
conversation and log on as the identity without any issues

3. MD5 is provably weak as a hash - see the work of Wang et al:

http://eprint.iacr.org/2004/199.pdf

4. Javascript on the client is not a trusted environment. Minimizing  
the trust of security weak components is a good design goal.

5. SSL is cheap. A certificate costs less than $100 these days and  
solves many of these issues.

Andrew



On 30/04/2006, at 5:55 PM, Ace123 wrote:

> Clicking on "Why this is secure" link on the yahoo login page gives  
> this:
>
> "Yahoo! now submits your ID and password securely via SSL (Secure
> Sockets Layer) encryption. This means that your personal information
> is more secure every time you sign in.
>
> In the past, Yahoo! used a challenge-response mechanism to protect
> passwords using MD5. Passwords were scrambled using a one-way hash, so
> that they could not be converted to clear text."
>
>
> What could be the reasons why yahoo changed their login security  
> mechanism?
>
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