A One Round Protocol for

Tripartite Diffie Hellman

By Dane Vanden Berg

● Antoine Joux● New form of an old Cryptographic

Method● Based off of ECDHE - Elliptic Curve

Diffie Hellman Ephemeral

Paper Abstract

● Cryptographical uses in day to day

● Brief introduction on Diffie-Hellman Protocol

● Elliptic Curve Cryptography

● One Round Protocol For Tripartite Diffie-Hellman

Full Ground

● Email● Secure Websites● Online Signatures● Purchases

Cryptography and You

● Discovered in 1976 ● the Diffie–Hellman protocol is one of the most

famous cryptographic primitives.● Intended for a shared secrecy of one key● Intended for perfect forward secrecy ● ( a.k.a Trapdoor Function? )

What is Diffie Hellman

Backround

Diffie Hellman

Merkle

Diffie Hellman Merkle Example

Bob Eve Alice b = 10 g=5 a = 8

p=23B=510 mod 23 A=58 mod 23

B=9A=16s=1610 mod 23 s=98

mod 23s= 13 s=13

B=9A=16

Another approach to public key cryptography

ECC - Elliptic curve cryptography

p: field parameters (modulo p)a,b: points on the curveG: Generator - cyclic groupn: ord(G) - number of pts in Gh: cofactor - should equal 1

Domain Parameters

Example

● Shorter Encryption Key● Fewer Resources● Compare how much energy it takes to break a crypto algorithm

and compare it to how much water you can boil.

Why Elliptic Curves

Tripartite Diffie Hellman

● Involves 3 participants● Single pass of communications● 1 can broadcast some data to other

2

Description

● Allows for 3 people instead of 2● Only one round of communication● Broadcasting doesn’t require all

parties to be “alive” at once● Trusted Third Party

Pros

Example of Trusted Third Party

● Open to middle man attacks● If keys aren’t certified people aren’t

sure who is who.

Flaws

https://blog.cloudflare.com/a-relatively-easy-to-understand-primer-on-elliptic-curve-cryptography/Joux, Antoine. “A One Round Protocol for Tripartite Diffie-Hellman.” Journal of Cryptology 17.4(2004):n. pag. Web.https://www.youtube.com/watch?v=F3zzNa42-tQhttps://tools.ietf.org/html/draft-urien-tls-dh-tripartite-00https://eprint.iacr.org/2004/079.pdf

Work Cited