# Towards Generalized Diffie-Hellman-esque Key Agreement via Generic Split KEM Construction

### Brian Goncalves, Atefeh Mashatan

#### 2024

#### Abstract

The Diffie-Hellman (DH) problem is a cornerstone of countless key agreement schemes. One of these schemes is the popular instant messaging protocol, Signal. The Signal protocol relies on a subprotocol based on the DH-problem in order to create a secure session key. Unfortunately, as the threat of robust quantum computers continues to loom over traditionally hard problems such as the DH problem, quantum-resistant replacements for these schemes must be created. One candidate for a drop-in DH-style replacement is a special type of key encapsulation mechanism (KEM) called a split KEM, which maintains the same message flow of DH key agreement schemes. In this work, we present an efficient combiner to construct a split from a public key encryption scheme, a signature algorithm, and a special type of pseudorandom function (PRF), called a constrained PRF. Constrained PRFs can produce PRF keys with limited domains, and by selecting the domain to be a single point, the master secret key can be reused. We then use the remaining schemes to transport the constrained key and point and ensure the authenticity of the source of the ciphertext. We then prove that our construction reaches the split KEM formulation of traditional IND-CCA-security with a tight reduction.

Download#### Paper Citation

#### in Harvard Style

Goncalves B. and Mashatan A. (2024). **Towards Generalized Diffie-Hellman-esque Key Agreement via Generic Split KEM Construction**. In *Proceedings of the 10th International Conference on Information Systems Security and Privacy - Volume 1: ICISSP*; ISBN 978-989-758-683-5, SciTePress, pages 594-608. DOI: 10.5220/0012454400003648

#### in Bibtex Style

@conference{icissp24,

author={Brian Goncalves and Atefeh Mashatan},

title={Towards Generalized Diffie-Hellman-esque Key Agreement via Generic Split KEM Construction},

booktitle={Proceedings of the 10th International Conference on Information Systems Security and Privacy - Volume 1: ICISSP},

year={2024},

pages={594-608},

publisher={SciTePress},

organization={INSTICC},

doi={10.5220/0012454400003648},

isbn={978-989-758-683-5},

}

#### in EndNote Style

TY - CONF

JO - Proceedings of the 10th International Conference on Information Systems Security and Privacy - Volume 1: ICISSP

TI - Towards Generalized Diffie-Hellman-esque Key Agreement via Generic Split KEM Construction

SN - 978-989-758-683-5

AU - Goncalves B.

AU - Mashatan A.

PY - 2024

SP - 594

EP - 608

DO - 10.5220/0012454400003648

PB - SciTePress