A One Round Protocol
for Tripartite Diffie
Hellman
By Dane Vanden Berg
Paper Abstract
● Antoine Joux
● New form of an old Cryptographic
Method
● Based off of ECDHE - Elliptic Curve Diffie
Hellman Ephemeral
Full Ground
● Cryptographical uses in day to day
● Brief introduction on Diffie-Hellman Protocol
● Elliptic Curve Cryptography
● One Round Protocol For Tripartite Diffie-Hellman
Cryptography and You
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Email
Secure Websites
Online Signatures
Purchases
What is Diffie Hellman
● 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? )
Backround
Diffie
Hellman
Merkle
Diffie Hellman Merkle Example
Bob
b = 10
B=510 mod 23
B=9
s=1610
mod 23
s= 13
Eve
g=5
Alice
a=8
p=23
B=9
A=16
A=58 mod 23
A=16
23
s=98 mod
s=13
ECC - Elliptic curve cryptography
Another approach to public key cryptography
Domain Parameters
p: field parameters (modulo p)
a,b: points on the curve
G: Generator - cyclic group
n: ord(G) - number of pts in G
h: cofactor - should equal 1
Example
Why Elliptic Curves
● 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.
Tripartite Diffie Hellman
Description
● Involves 3 participants
● Single pass of communications
● 1 can broadcast some data to other 2
Pros
● 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
Example of Trusted Third Party
Flaws
● Open to middle man attacks
● If keys aren’t certified people aren’t
sure who is who.
Work Cited
https://blog.cloudflare.com/a-relativelyeasy-to-understand-primer-on-ellipticcurve-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-tQ
https://tools.ietf.org/html/draft-urien-tls-dh-tripartite-00
https://eprint.iacr.org/2004/079.pdf