Julien Piet

Hello!

I am a Research Scientist at Google DeepMind, focused on the security and privacy of large language models. My interests lie in AI security and AI for security.

I obtained my Ph.D. from UC Berkeley in 2026, advised by Professors Vern Paxson and David Wagner. My dissertation is available here.

Email: piet@berkeley.edu
GitHub / Linkedin / Twitter

About me

I am originally from France, where I got my B.S. from Ecole polytechnique and my M.S. from Universite Paris 7. I am a member of the Corps des Mines.

Previous professional experience:

Worked with Prof. Vern Paxson at Corelight from 2020 to 2026
Interned at Google Cloud as a Student Researcher in 2025 while developping Matryoshka
Worked for Thales in operational research, with Florian Simonneau and Sébastien Kervarec. 2018-2019
Interned at Cisco, working with Dr. David McGrew and Dr. Blake Anderson. 2018

Preprints

2026

Parser-Free Querying of Security Logs. Evan Luo, Julien Piet, David Wagner.
Web Agents Should Adopt the Plan-Then-Execute Paradigm. Julien Piet, Annabella Chow, Yiwei Hou, Muxi Lyu, Sylvie Venuto, Jinhao Zhu, Raluca Ada Popa, David Wagner.
Trojan Hippo: Weaponizing Agent Memory for Data Exfiltration. Debeshee Das, Julien Piet, Darya Kaviani, Luca Beurer-Kellner, Florian Tramèr, David Wagner.

2025

Semantic-Aware Parsing for Security Logs. Julien Piet, Vivian Fang, Rishi Khare, Scott Coull, Vern Paxson, Raluca Ada Popa, David Wagner.

Publications

2025

Mark My Words: Analyzing and Evaluating Language Model Watermarks. Julien Piet, Chawin Sitawarin, Vivian Fang, Norman Mu, David Wagner. SaTML 2025.
StruQ: Defending Against Prompt Injection with Structured Queries Sizhe Chen, Julien Piet, Chawin Sitawarin, David Wagner. USENIX 2025.
JailbreaksOverTime: Detecting Jailbreak Attacks Under Distribution ShiftJulien Piet, Xiao Huang, Dennis Jacob, Annabella Chow, Maha Alrashed, Geng Zhao, Zhanhao Hu, Chawin Sitawarin, Basel Alomair, David Wagner. AISEC 2025.

2024

Jatmo: Prompt Injection Defense by Task-Specific Finetuning Julien Piet, Maha Alrashed, Chawin Sitawarin, Sizhe Chen, Zeming Wei, Elizabeth Sun, Basel Alomair, David Wagner. ESORICS 2024.
Mempool Privacy via Batched Threshold Encryption: Attacks and Defenses. Arka Rai Choudhuri, Sanjam Garg, Julien Piet, Guru-Vamsi Policharla. USENIX 2024.
Toxicity Detection for Free Zhanhao Hu, Julien Piet, Geng Zhao, Jiantao Jiao, David Wagner. NeurIPS Spotlight 2024.

2023

Network Detection of Interactive SSH Impostors Using Deep Learning. Julien Piet, Aashish Sharma, Vern Paxson, David Wagner. USENIX 2023.
GGFAST: Automating Generation of Flexible Network Traffic Classifiers. Julien Piet, Anthony Kasza, Dubem Nwoji, Vern Paxson. SIGCOMM 2023.
MEVade: An MEV-Resistant Blockchain Design. Julien Piet, Vivek C Nair, Sanjay Subramanian. ICBC 2023.
Asymmetric Certified Robustness via Feature-Convex Neural Networks. Samuel Pfrommer, Brendon G. Anderson, Julien Piet, Somayeh Sojoudi. NeurIPS 2023.

2022

Extracting Godl [sic] from the Salt Mines: Ethereum Miners Extracting Value. Julien Piet, Jaiden Fairoze, and Nicholas Weaver. WEIS 2022.

2021

Rachat des start-up : des racines françaises, des ailes étrangères. Julien Piet and Marc Revol. La Fabrique de l'Industrie, 2021.

2018

An In-Depth Study of Open-Source Command and Control Frameworks. Julien Piet, Blake Anderson, and David McGrew. International Conference on Malicious and Unwanted Software 2018.

Julien Piet

About me

Preprints

2026

2025

Publications

2025

2024

2023

2022

2021

2018

Patents

2021

2020