Writing

An MPC wallet has no seed to derive from, but the BIP32 tweak is just an addition, so every party can shift its share by the same public amount and get a child key that no one ever holds.

Oct 2026

How BIP32 derives a whole tree of keys from a single seed, why public keys can be derived without the private key, and what hardened derivation protects against.

Oct 2026

A walkthrough of an inventory-based off-ramp: one-time deposit wallets, webhook-driven order tracking, treasury sweeping, payout funding, and reconciliation.

Fystack · Sep 2026

Finality differs a lot between Bitcoin, Ethereum, Solana and Stellar. Notes on designing a deposit pipeline that treats confirmation as a per-chain policy instead of one number.

Sep 2026

Why role-based access control isn't enough for value-moving actions, and how a policy engine evaluates amount, destination, and contract calls between permission and execution.

Fystack · Jun 2026

How we made our container builds verifiable with isolated provenance generation, keyless signing, and SBOM attestations.

Fystack · Apr 2026

A Schnorr proof of knowledge, step by step: why it convinces a verifier, why it leaks nothing, how Fiat-Shamir removes the interaction, and how the same ideas scale to proving arbitrary programs.

Oct 2026

Reusing, or even slightly biasing, a single random value in ECDSA leaks the private key. A short walk through the algebra, the real incidents, and how modern schemes avoid the problem.

Oct 2026

ECDSA needs the inverse of the nonce, which isn't linear. A walk through multiplicative-to-additive conversion, and how parties produce a standard ECDSA signature from shares of k and d.

Sep 2026

The polynomial math behind splitting a private key into shares, why any t shares reconstruct it and t-1 reveal nothing, and how Lagrange coefficients let parties sign without ever assembling the key.

Aug 2026

Following one transfer through signing, the mempool, a block, and consensus, using only hashes, keys and signatures as the building blocks.

Jul 2026

The signing and verification equations of ECDSA and Ed25519, why each verification works, and the practical differences that show up on chains like Bitcoin, Ethereum, Solana and Stellar.

Jun 2026

How a private key becomes a public key through elliptic curve multiplication, why you can't go backwards, and how addresses and signatures are built on top.

May 2026

What a cryptographic hash function promises, what each promise is used for in a blockchain, and why Bitcoin and Ethereum don't use the same one.

May 2026