theory: unconditional security

[Amir Herzberg]

> 	I suspect you find little written about OTP work because people
have
> always assumed the keys were impractical to distribute, store and
> use.

Another concern with OTP and other unconditionally-secure schemes is
that they usually require limited number of applications of the key
(usually, use once). This introduces a substantial synchronization /
reliability / security problem for many applications. 

Notice that unconditionally secure authentication and signatures are in
fact used in scenarios where the limited use can be easily assured, such
as in online/offline signatures, used e.g. for micropayments and for
multicast encryption. In these cases, a `regular` offline signature
(e.g. RSA) is used to sign in advance (offline) the public key of the
one-time signature scheme. The one-time signature is applied when
processing online the message to be signed (with very little time). Of
course, the reason one-time signatures are used for these applications
is because they are faster, not because they are unconditionally secure.


Regards, Amir Herzberg
See http://amir.beesites.co.il/book.html  for lectures and
draft-chapters from book-in-progress, `secure communication and commerce
using cryptography`; feedback welcome!



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