Domènec Madrid
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  • What Grinding Has Actually Saved on Chain

    Low-r grinding saves a byte per signature. I did the accounting over every ECDSA signature ever mined, to see what that adds up to and how much is still being left on the table.

    30 min read   ·   August 16, 2026

    2026   ·   Bitcoin   Cryptography   Signatures   Low-r grinding   Rust   Blockchain Analysis

  • Modifying the bdk_wallet Balance API for My Summer of Bitcoin Project

    How I changed the way bdk_wallet decides which unconfirmed coins count as trusted, by following where the money came from instead of which keychain it landed on.

    10 min read   ·   August 14, 2026

    2026   ·   Bitcoin   BDK   Rust   Wallets   Summer of Bitcoin   Open Source

  • Is Hardware Wallet Fingerprinting Even Possible?

    Can you tell which hardware wallet signed a Bitcoin transaction just by looking at its ECDSA or Schnorr signature? We tested ten devices and found out.

    12 min read   ·   April 01, 2026

    2026   ·   Bitcoin   Cryptography   Hardware Wallets   Wallet Fingerprinting   Signatures   Privacy

  • Covert-Nonce Channel Attacks on Bitcoin Hardware Wallets

    How a compromised hardware wallet can silently leak your Bitcoin seed through the signatures it produces — and what the Anti-Exfil protocol does to stop it.

    6 min read   ·   September 01, 2025

    2025   ·   Bitcoin,   Cryptography,   Hardware   Wallets,   Signatures

  • Build Your Own Bitcoin Main-net

    How we built a fully isolated Bitcoin mainnet replica in Docker — same genesis block as the real network, zero-cost transactions, and hardware wallet support out of the box.

    7 min read   ·   May 01, 2025

    2025   ·   Bitcoin,   Docker,   Testing,   Core,   DevOps

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