Jeremiah Blocki

CASH: A Cost Asymmetric Secure Hash Algorithm for Optimal Password Protection

2015 · arXiv (Cornell University)

An adversary who has obtained the cryptographic hash of a user's password can mount an offline attack to crack the password by comparing this hash value with the cryptographic hashes of likely password guesses. This …

The Parallel Reversible Pebbling Game: Analyzing the Post-Quantum Security of iMHFs

2021 · arXiv (Cornell University)

The classical (parallel) black pebbling game is a useful abstraction which allows us to analyze the resources (space, space-time, cumulative space) necessary to evaluate a function $f$ with a static data-dependency graph $G$. Of particular …

Cost-Asymmetric Memory Hard Password Hashing

2022 · arXiv (Cornell University)

In the past decade, billions of user passwords have been exposed to the dangerous threat of offline password cracking attacks. An offline attacker who has stolen the cryptographic hash of a user's password can check …