A notebook by the fire
Sam Schlesinger
Cryptography, formalization, and the mathematics of freedom.
I work on cryptographic systems for human autonomy. By day, that means designing privacy-preserving authentication for billions of users at Google Chrome and chairing the W3C Anti-Fraud Community Group, drafting standards meant to become libraries deployed across the open web.
In the open, I formalize mathematics in Lean 4, record explainers on theoretical computer science at Computable Secrets, and write essays on the cryptographic primitives that protect free societies. The pieces are connected: deployment teaches what theory misses; theory teaches what deployment skips; explanation forces both to be honest.
Selected work
Anonymous Tokens with Hidden Metadata
IETF draft · implementation deployed for spam mitigation between RCS and iMessage
Anonymous Credit Tokens
IETF draft extending privacy-preserving authentication to rate-limited credentials
Open Conjecture Formalizations
Lean 4 formalizations of major open problems in mathematics and theoretical computer science
Computable Secrets
YouTube channel on theoretical computer science, cryptography, and formalization
Recent writing
Freedom as a Protocol Property
The politics of computation is often hidden in what the protocol remembers.
The Birthday Paradox
An entire family of attacks on cryptographic hash functions hides inside a parlour-trick about shared birthdays.
Rate Limits Without Identity
A good credential system lets a service say no without first learning who you are.
Proofs as Infrastructure
Formalization turns mathematical trust from a mood into a maintenance discipline.
The Collatz Map in Binary
Strip the zeros, then watch a carry ripple: the most famous open problem in arithmetic is a statement about bit-strings.