How Google is preparing for a post-quantum world
Phil Venables
VP, TI Security & CISO, Google Cloud
The National Institute of Standards and Technology (NIST) on Tuesday announced the completion of the third round of the Post-Quantum Cryptography (PQC) standardization process, and we are pleased to share that a submission (SPHINCS+) with Google’s involvement was selected for standardization. Two submissions (Classic McEliece, BIKE) are being considered for the next round.
We want to congratulate the Googlers involved in the submissions (Stefan Kölbl, Rafael Misoczki, and Christiane Peters) and thank Sophie Schmieg for moving PQC efforts forward at Google. We would also like to congratulate all the participants and thank NIST for their dedication to advancing these important issues for the entire ecosystem.
This work is incredibly important as we continue to advance quantum computing. Large-scale quantum computers will be powerful enough to break most public-key cryptosystems currently in use and compromise digital communications on the Internet and elsewhere. The goal of PQC is to develop cryptographic systems that safeguard against these potential threats, and NIST’s announcement is a critical step toward that goal. Governments in particular are in a race to secure information because foreign adversaries can harvest sensitive information now and decrypt it later.
At Google, our work on PQC is focused on four areas: 1) driving industry contributions to standards bodies; 2) moving the ecosystem beyond theory and into practice (primarily through testing PQC algorithms); 3) taking action to ensure that Google is PQC ready; and 4) helping customers manage the transition to PQC.
Driving industry contributions to a range of standards bodies
In addition to our work with NIST, we continue to drive industry contributions to international standards bodies to help advance PQC standards. This includes ISO 14888-4, where Googlers are the editors for a standard on stateful hash-based signatures. More recently, we also contributed to the IETF proposal on data formats, which will define JSON and CBOR serialization formats for PQC digital signature schemes. These standards, collectively, will enable large organizations to build PQC solutions that are compatible and ease the transition globally.
Moving the ecosystem beyond theory and into practice: Testing PQC algorithms
We’ve been working with the security community for over a decade to explore options for PQC algorithms beyond theoretical implementations. We announced in 2016 an experiment in Chrome where a small fraction of connections between desktop Chrome and Google's servers used a post-quantum key-exchange algorithm, in addition to the elliptic-curve key-exchange algorithm that would typically be used. By adding a post-quantum algorithm in a hybrid mode with the existing key-exchange, we were able to test its implementation without affecting user security.
We took this work further in 2019 and announced a wide-scale post-quantum experiment with Cloudflare. We worked together to implement two post-quantum key exchanges, integrated them into Cloudflare’s TLS stack, and deployed the implementation on edge servers and in Chrome Canary clients. Through this work, we learned more about the performance and feasibility of deployment in TLS of two post-quantum key agreements, and have continued to integrate these learnings into our technology roadmap.
In 2021, we tested broader deployment of post-quantum confidentiality in TLS and discovered a range of network products that were incompatible with post-quantum TLS. We were able to work with the vendor so that the issue was fixed in future firmware updates. By experimenting early, we resolved this issue for future deployments.
Taking action to ensure that Google is PQC ready
At Google, we’re well into a multi-year effort to migrate to post-quantum cryptography that is designed to address both immediate and long-term risks to protect sensitive information. We have one goal: ensure that Google is PQC ready. Internally, this effort has several key priorities, including securing asymmetric encryption, in particular encryption in transit. This means using ALTS, for which we are using a hybrid key-exchange, to secure internal traffic; and using TLS (consistent with NIST standards) for external traffic. A second priority is securing signatures in the case of hard-to-change public keys or keys with a long lifetime, in particular focusing on hardware, especially hardware deployed outside of Google's control.
We’re also focused on sharing the information we learn to help others address PQC challenges. For example, we recently published a paper that includes PQC transition timelines, leading strategies to protect systems against quantum attacks, and approaches for combining pre-quantum cryptography with PQC to minimize transition risks. The paper also suggests standards to start experimenting with now and provides a series of other recommendations to allow organizations to achieve a smooth and timely PQC transition.
Helping customers manage the transition to PQC
At Google Cloud, we are working with many large enterprises to ensure they are crypto-agile and to help them prepare for the PQC transition. We fully expect customers to turn to us for post-quantum cloud capabilities, and we will be ready. We are committed to supporting their PQC transition with a range of Google products, services, and infrastructure. As we make progress, we will continue to provide more PQC updates on Google core, cloud, and other services, and updates will also come from Android, Chrome and other teams. We will further support our customers with Google Cloud transformation partners like the Google Cybersecurity Action Team to help provide deep technical expertise on PQC topics.
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