Applied Cryptography

About Ledger
We're a team of experts pushing the limits of what's possible, united by our common goal to unlock true freedom through digital ownership, making technology accessible for all. We believe in a world where users, creators and enterprises manage their value with ownership and freedom. Our curiosity drives us to innovate, empowering individuals on a global scale. We believe change is constant and our team moves forward as one, with a culture of problem-solving where every employee is empowered and supported to challenge tradition and create solutions. Our mission is simple: to make self-custody accessible and give people the keys to their own financial futures. If you want to make a true impact, we want you to join us at Ledger.

At Ledger, we're proud to be the global platform for digital assets and Web3, with over 20% of the world's crypto assets secured through our Ledger devices. With our headquarters in Paris, and offices in Vierzon, Grenoble, Montpellier, London, Portland, Geneva, Zurich and Central Singapore, we have a team of around 600 professionals developing a variety of products and services to enable individuals and companies to securely buy, store, swap, grow and manage crypto assets – including the Ledger hardware wallets line with more than 7.5 millions units already sold in 200 countries.

Internship duration: 6 months
The team
The Donjon is Ledger's dedicated internal security evaluation and research team. Its mission encompasses rigorously attacking and evaluating every component of Ledger's offerings, from the physical hardware wallets (devices) to the associated software applications (apps). This continuous, proactive adversarial approach is fundamental to maintaining and reinforcing Ledger's industry leadership in secure digital asset management. The Donjon also drives advanced cryptographic innovation, actively researching and implementing cutting-edge techniques. This mission is vital to continually elevate the security and privacy of Ledger's products, ensuring resilience against emerging threats and future-proofing digital security.

What You'll Be Doing

• Context: We are investigating the integration of zero-knowledge succinct proofs of validity, such as SNARKs, into our hardware devices. Our hardware signers utilize a Secure Element (SE) for sensitive operations; however, this chip has limited resources (memory and computing power). For emerging use cases, like Clear Signing, this resource constraint can severely impact performance or even prevent the SE from executing complex operations. Succinct proofs of validity offer a solution by allowing complex computations to be offloaded to an untrusted platform (such as a user's PC, mobile phone, or a server). The result is accompanied by a proof that the Secure Element can verify efficiently, thereby mitigating the performance challenges associated with constrained resources.
• Objective: The goal of this internship is to assess the practicality of deploying the verification logic for a succinct proof system onto a constrained Secure Element. The initial phase will involve selecting the most suitable open-source proof system after a thorough study of available options. This will be followed by a benchmarking exercise to measure the performance of proof verification across standard use cases. Furthermore, there is potential to develop optimizations for the proof logic specifically tailored to the Secure Element's constraints.

• Proof systems that will be considered include (but might not be limited to):

• RISC Zero

• SP1 by Succinct Labs
• Stwo prover by Starkware
• Nexus zkVM

What We're Looking For

• The candidate should have a strong background in cryptography, some basic knowledge of zero-knowledge succinct proof systems, and be comfortable with coding.

Nice To Have

• Experience with development on embedded devices (microcontrollers, etc.) is a plus.

Benefits
At Ledger, we are dedicated to continually investing in our employees which is why we offer more than just salaries; we provide comprehensive compensation packages that include a wide range of benefits. Here are some of the benefits you can look forward to:

• Social: Frequent social events, snacks and drinks
• Transportation allowance: Ledger offers a commuter allowance to contribute to your preferred means of transportation.
• Lunch vouchers: Ledger offers a meal allowance with Swile
• Vacation: 1 day off for every full month of work, in addition to national holidays
• Compensation: €1,500 a month

For regionally specific benefits, your Talent Acquisition contact will be able to provide you with more information.

We're committed to building an inclusive hiring process. If you need any adjustments or accommodations, just let us know, we'll do our best to support you.