Cowrie Research

seedhammer-primary-sources-2026-05-01

4 min read

SeedHammer primary-source snapshot

Fetched: 2026-05-01 UTC

1) Official site

Source: https://seedhammer.com/

Selected excerpts from the official site:

SeedHammer eliminates the need for storing a descriptor.

Any combination of M-of-N plates contain enough data for a full recovery.

The controller software is open source and runs on the same air gapped hardware as SeedSigner.

Additional signals from the source:

  • The homepage makes the main differentiator explicit: SeedHammer is not just engraving seed words onto metal, it is trying to make multisig backups self-contained
  • The site also emphasizes QR-code recovery, stateless operation, and no wireless capabilities, which pushes the project firmly into backup-and-recovery infrastructure rather than ordinary accessories

2) FAQ

Source: https://seedhammer.com/faq

Selected excerpts from the FAQ:

What do you mean by “self-contained” setup?

This means that the minimum amount of shares (physical plates) is enough to recover the wallet, and the need for storing a copy of the XPUBs (often in the form of a descriptor) digital or on paper along each backup/plate is eliminated.

Will the SeedHammer controller generate a seed?

No, the SeedHammer software will never be able to generate a seed phrase because of the obvious vulnerabilities this approach would introduce.

Additional signals from the source:

  • The FAQ makes clear that SeedHammer supports both single-sig and multisig wallet backups but sees self-contained multisig recovery as the flagship feature
  • It also shows the project thinking carefully about scope boundaries: the controller is for engraving and recovery integrity, not for convenient seed generation

3) Descriptor partitioning article

Source: https://seedhammer.com/article/the-seedhammer-descriptor-partitioning-scheme

Selected excerpts from the article:

Creating secure and durable backups for multisig wallets necessitates the storage of both private and public keys.

The standard supports a fountain encoding scheme which allows combining data shares with the XOR operator.

Every combination of 3 shares recovers all 6 parts.

Additional signals from the source:

  • This article is one of the strongest categorization signals because it shows the product contains a real backup scheme, not merely branded metal plates
  • The article also ties SeedHammer to UR/output-descriptor standards and explains how descriptor fragments are sized for real engraving and QR scanning constraints

4) Attack-vectors article

Source: https://seedhammer.com/article/attack-vectors

Selected excerpts from the article:

The risk we are defending against is exfiltration of seed phrases that the SeedHammer has come into contact with.

The entire system, from the hammering machine to the Raspberry Pi Zero controller, is completely air-gapped from the internet.

simply remove the SD card before entering any seeds.

Additional signals from the source:

  • The article is useful because it exposes the project’s real threat model: sound, radio, electromagnetic leakage, supply-chain risk, and data exfiltration are all considered explicitly
  • SeedHammer’s repeated emphasis on not generating seeds, verifying downloaded images, and optionally removing the SD card reinforces that the controller is treated as sensitive backup infrastructure

5) Firmware repository / README

Sources:

Selected excerpts from the repo:

This repository contains the source code to run the controller program for the SeedHammer II engraving machine.

The hardware is open source.

The build process is designed to be deterministic, that is, images produced with the above steps should match the released images bit-for-bit, except for the signature.

Additional signals from the source:

  • The repo confirms that SeedHammer is shipping a real controller stack with deterministic-build goals rather than merely publishing marketing copy around a hardware product
  • The install/update flow through UF2 images and the development/debug instructions make the controller feel like mature device firmware, not a side project script

6) Hardware repository / README

Sources:

Selected excerpts from the repo:

This repository contains the design files for the SeedHammer II machine.

The schematic and PCB are in KiCad format.

The CAD files for the custom machine parts are in STEP format.

Additional signals from the source:

  • The separate hardware repo is especially high-signal because it shows that the project publishes PCB and CAD artifacts, not just firmware
  • That open-hardware posture helps distinguish SeedHammer from proprietary backup accessories or one-off DIY guides

Notes

  • SeedHammer appears best cataloged as bitcoin self-custody backup infrastructure / self-contained multisig steel-backup system / air-gapped engraving controller.
  • No canonical standalone whitepaper or litepaper surfaced in this pass.
  • The most useful primary sources were the homepage, FAQ, descriptor-partitioning and attack-model articles, plus the firmware and hardware repos.

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