Subject: [saag] A way to bootstrap post Quantum key distribution.

From: Phillip Hallam-Baker <[email-masked]>
Date: Tue, 5 Mar 2019 10:57:00 -0500

Let us say for the sake of argument someone managed to build a working
computer capable of breaking RSA and released it this week. What would we
do?

As things stand, we have no post quantum public key algorithm for
encryption. We have hash signatures of course but the only scheme we need
for encryption is Kerberos. And we would need some means of bootstrap.

[Yes, CAs become KDCs, uggggly. If you have a better plan, put it on the
table.]

One of the schemes I have developed as part of my UDF project is an
encryption key presented as a QR code that is used to form a locator. It
occurred to me that this scheme could be used to bootstrap a kerberos
scheme by using the postal mail as out of band key distribution.

The spec is submitted as an internet draft of course but it is much easier
to read in the HTML format as the superscripts and such are preserved in
the math:

http://mathmesh.com/Documents/draft-hallambaker-mesh-udf.html

This is not what I designed the scheme for of course. The original
application was to enable people to pay bills by putting a QR code on the
paper invoice. The real point of electronic bill payment being to encourage
prompt payment rather than to save the postage  (though the QR code version
could bootstrap that as well).

It seems to me that it is more likely governments will fund research into
disaster preparation schemes lest quantum happen than the bill payment
application. But encouraging use of the Encrypted QR Codes would serve
disaster prep as well as payment.

The scheme is unencumbered as far as I am aware. I discussed the idea with
people as far back as when I was with W3C. It wasn't interesting then as we
didn't all carry barcode scanners with us all the time in those days.

---

From: Vadym Fedyukovych <[email-masked]>
Date: Tue, 12 Mar 2019 19:19:39 +0200

> ..we have no post quantum public key algorithm for
> encryption.  ..

This is a strong statement, and no argument was given in favor of it.

ElGamal encryption is the well-known one that can be instantiated
with modular multiplication and elliptic curve groups.
Supersingular isogeny key exchange (sike.org) is a post-quantum candidate
DH-like protocol, with no fast quantum attack known today.

To connect the dots, ElGamal is essentially a key exchange
with public key of the message recipient and one-time key of the sender.

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