Re: An Honest and Simple Question.

adacrypt <austin.obyrne@xxxxxxxxxxx> writes:

On Jul 17, 4:50 pm, adacrypt <austin.oby...@xxxxxxxxxxx> wrote:

[...]

Dou you mean that whitfield Diffie was ahead of the RSA team (was that
why you state 1976 i.e. predating RSA - if not, what other cipher
demonstrates asymmetry ?) - he was unable to find an asymmetric cipher
himself so he hopped the ball in US academia - the result was the RSA
cipher ? - why did he call it asymmetric - I was not a bit impressed
with the popular accounts of his so-called 'discovery'.

I'm not an expert (and most certainly not an expert in the history) so
probably this is a gross oversimplification.

Whitfield Diffie and Martin Hellman's 1976 paper presented the
possibility of a new kind of cryptography that we now call asymmetric or
public key cryptography. They presented a concrete example, now called
Diffie Hellman (DH) which is a key agreement protocol: it lets two
people openly (without any secret shared information) negotiate a number
which only they will know. They also presented a scheme based on DH
that's more recognisably a public key cryptosystem though that's not
used as far as I know. The paper also outlines authentication schemes
that we'd now call digital signatures referencing yet earlier (non-RSA)
work. So it describes the three kinds of public key (asymmetric)
cryptosystems, even though as far as I know only DH is still used.

For my information do you know of a previous use of asymmetric
algoritms ?

The DH paper references earlier work by Leslie Lamport; I've no idea
whether that was actually used. Part of the sudden growth of public
cryptography was a coincidence of realising how such schemes could be
constructed and the availablity of computing power making such schemes
practical.

A variety of ideas for trapdoor functions that could form public key
systsms were proposed (and continue to be) but IIUC basically DH, RSA,
DSA, ElGamal, remain. (And the EC variants of DH, DSA, ElGamal.)

Do you think that the percieved benefits of asymmetry wiould carry
forward to any other cipher-type that also uses asymmetric mathematics
but is secuired by randomness - adacrypt

The use of all schemes requires randomness. In DH both parties choose a
random number, in RSA (if used for encryption) one generates a random
session key which is encrypted using the RSA public key, in DSA (a
digital signature scheme) one needs a fresh random number to sign
anything. (When used for signing, RSA doesn't require randomness, and
you don't need randomness for verifying RSA or DSA signatures or for
decrypting with RSA.) For all schemes you need randomness to generate
keypairs in the first place (well, not DH which doesn't use persistent
keys in that way, but you need randomness each time you use DH).
.

Relevant Pages

  • Re: An Honest and Simple Question.
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