[cryptography] Math corrections

James A. Donald jamesd at echeque.com
Mon Sep 19 02:06:24 EDT 2011


Marsh Ray wrote:
>> But the failure of *any* single CA allows a successful attack on *every*
>> user connecting to *every* https website.

On 2011-09-19 2:48 PM, Arshad Noor wrote:
> Would you care to explain this in more detail, Marsh?
>
> Please feel free to frame your explanation as if you were
> explaining this to a 6-year old.

Assume I have control over a CA, one obscure and minor CA that no one 
has ever heard of, and hardly anyone uses.  Perhaps I have hacked them. 
Perhaps I am an Islamic preacher whose congregation is apt to blow up 
those that displease me, due to their sadly regrettable misunderstanding 
of Islam. Perhaps I am chief of police in some third world terror state 
such as Iran.  Perhaps I am someone important at Harvard, or someone 
important in a Russian Mafia.

I want to intercept, and perhaps modify, all email to google.  I get an 
intercept going through any of the notorious flaws in major routers, so 
that when a browser attempts to connect to https://mail.google.com, it 
in fact connects to my server, which may then connect to the real 
https://mail.google.com

I have my obscure and minor CA issue me a certificate for 
https://mail.google.com

I intercept all communications between https://mail.google.com and Iran. 
  I have a keyword program check all the mail for bad words and 
forbidden topics.  Any Iranian who writes inappropriate thoughts in a 
gmail gets tortured, and any Harvard student who writes inappropriate 
thoughts in a gmail gets failed.

Heaven help the poor Harvard student who wrote to his friend that his 
parents were giving him a niggardly allowance.




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