[Cryptography] Public-key auth as envisaged by first-year science students

[John Denker]

In the context of:

>> Location-limited channels: Detect how long it takes for messages to go back
>>  and forth, the MITM will introduce delays.

On 08/10/2016 11:27 AM, Ron Garret wrote:

> A side-channel defense against an attack!  I love it!

Keep in mind that the defense is at best weak.  It makes things
tamper-evident, not tamper-proof.

Making things tamper-evident opens you up to a large class
of DoS attacks.  All somebody needs to do is break your
tamper-evident seals;  then what are you going to do?

  Specifically:  Suppose the voting machines arrive at the
  polling place with their seals broken.  Suppose this
  affects selected precincts but not others.  Then what
  are you going to do?  Cancel the election?  

All these ideas are not new.

  For example:  In the years leading up to WWII, the Japanese
  government required all overseas telegrams to be delayed by
  arbitrary amounts, to help defeat timing-based defenses.
  Reference:  Kahn.