International Association
for Cryptologic Research

The development of quantum computing technology poses a serious and credible threat to modern public-key cryptography, which is a pillar of secure communications. Post quantum cryptographic (PQC) algorithms can protect against this threat, but key establishment protocols supporting PQC algorithms pose non-trivial overhead costs. Prior proposals have pointed to the use of strategic traditional/PQC protocol combinations as a means of balancing performance and security, namely as an amortization of PQC overhead. This work provides the first benchmarking of this method within the context of the Messaging Layer Security (MLS) protocol. Comparative metrics include group size, CPU cycles, bytes, and runtime. The results show substantial overhead savings across the board when compared to a simple post-quantum cipher suite use, and marginal increase over traditional cipher suite performance when amortized. At small group sizes such as 1-to-1 channels, the method performs comparably to MLS using a traditional cipher suite. This work shows viability of deploying PQC solutions for constrained settings and and achieving PQC security with efficiency.