once more, with feeling.

[James A. Donald]

Leichter, Jerry wrote:
> The problem is what that "something else" should be.  Keyfobs with
> one-time passwords are a good solution from the pure security point
> of view, but (a) people find them annoying; (b) when used with
> existing input mechanisms, as they pretty much universally are, are
> subject to MITM attacks.  The equivalent technology on a USB plugin
> is much easier on the user in some circumstances, but is subject to
> some bad semantic attacks, as discussed here previously.  Also, it's
> not a great solution for mobile devices.
> 
> DoD/government uses smartcards, but that's probably not acceptable to
> the broad population.  There's been some playing around with cellphones
> playing the role of smartcard, but cellphones are not inherently secure
> either. 


Cellphones are not inherently secure, but *could* be inherently secure. 
  Each cellphone sim card has a unique identity.  It is possible to 
guarantee that a message goes to or from a cellphone containing a 
particular sim card - but present phone software provides no means to do 
this.

If a cellphones has nfc communications capable of talking to a pc, then 
the whole interaction could be made painlessly automatic - touch your 
cellphone to the pc nfc sensor to login to the website, touch it to the 
security door to unlock the security door, touch it to the cash 
register, observe the indicated payment on the cellphone screen, and 
press OK, touch it to the screenless, keyboardless atm, and the 
interaction comes up on your phone screen instead of the ATM screen, 
touch cellphones to pay money from one individual to another.

The major obstacle is that the government would want a strong binding 
between sim cards and true names, which is no more practical than a 
strong binding between physical keys and true names.

Absent useful cellphone software, passwords must suffice.  With a limit 
on the number of guesses before people get locked out, passwords *do* 
suffice - but then we need a means to unlock the account, and a means of 
password recovery.

Although cellphones and email are insecure, a use once short lived 
password emailed or instant messaged to the user is secure enough. 
Trouble is, what happens if the user's email account is stolen?

I had this problem.  I was using my hotmail account as the password 
recovery account for various high value domain names.  Someone called up 
hotmail's password recovery, and human engineered a password reset out 
of the hotmail staff, and then used email based password recovery to 
seize my domain names.  I eventually got them back, using reset 
passwords snail mailed to my physical post office box, and now  the 
email account associated with my domain names is at a service that 
provides no password recovery mechanism - and therefore provides an 
attacker with a very large number of opportunities to guess, requiring 
an insanely strong password.

Snail mail to a post office box is a secure password reset mechanism, 
short of a well timed physical attack on the post office.

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