Obtain SeedSigner's SHA-256 manifest

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SeedSigner publishes a small plaintext manifest alongside each software release.

For v0.8.7, the file is: seedsigner.0.8.7.sha256.txt
 

This file contains the expected SHA-256 hash for each official SeedSigner image.

For v0.8.7, the manifest contained:

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Pi Zero: 67f005c7ace26500a78be3f4d97eaf02d76d018550ec54df011741dde1933ce9

File: seedsigner_os.0.8.7.pi0.img

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Pi Zero 2 W / Pi 3: f38237cdde39efca2fb9e3b3f9f8b0beff2248767f85289bd50657fa69b54f1f

File: seedsigner_os.0.8.7.pi02w.img

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Pi 2: 9fc7f2ea8462e1c9d62efe41301e12d559e8f155653913e33c93e905360bb813

File: seedsigner_os.0.8.7.pi2.img

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Pi 4: 3c2a11a2303abf2a73b10be913d44a1eb85d5e5a15b5389a670cb963afd1e28b

File: seedsigner_os.0.8.7.pi4.img

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These are the exact four values contained in the v0.8.7 manifest used for this website's verifier.

However, simply obtaining these hashes is not enough.

If somebody were able to replace the SeedSigner software download, they could theoretically also replace a plaintext checksum file. We therefore need to authenticate the checksum file itself.

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Obtain SeedSigner's signature

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SeedSigner also publishes a detached PGP signature alongside the checksum manifest:

seedsigner.0.8.7.sha256.txt.sig

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This signature was created using the SeedSigner project's private signing key.

A valid signature allows us to determine whether the checksum manifest has been modified after it was signed.

SeedSigner's own verification instructions specifically require users to verify this signature before trusting the hashes contained in the manifest.

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Obtain SeedSigner's public key independently

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To verify the signature, I obtained SeedSigner's public PGP key from their Keybase identity:

https://keybase.io/seedsigner/pgp_keys.asc

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SeedSigner's official verification documentation itself directs users to obtain and compare the SeedSigner key through Keybase.

The complete fingerprint of that public key is:

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4673 9B74 B56A D88F 14B0 882E C7EF 7090 0726 0119

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The last 16 characters (commonly used as the key ID) are:

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C7EF 7090 0726 0119

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or without spaces:

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C7EF709007260119

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This fingerprint is extremely important.

A valid PGP signature by itself only tells us that a particular private key created the signature. Checking the fingerprint separately is what allows us to establish that the key being used is the SeedSigner project's published signing key.

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Verify the signature against the manifest

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I then cryptographically verified: seedsigner.0.8.7.sha256.txt.sig

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against: seedsigner.0.8.7.sha256.txt

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using the SeedSigner public key.

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GPG reported: Good signature from "seedsigner <btc.hardware.solutions@gmail.com>"

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It also reported that the signature used the RSA key:

46739B74B56AD88F14B0882EC7EF709007260119

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and displayed the primary key fingerprint:

4673 9B74 B56A D88F 14B0 882E C7EF 7090 0726 0119

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The signature itself was recorded as having been made on:

7 July 2026 at 17:03:45 UTC

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Most importantly, the fingerprint produced during verification exactly matched the fingerprint of the SeedSigner public key obtained from Keybase.

SeedSigner's documentation says that a successful verification should report “Good signature”, followed by an independent comparison of the signing-key fingerprint.

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What this proves

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At this stage we had established two important facts.

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First, the PGP signature was mathematically valid for the exact contents of: seedsigner.0.8.7.sha256.txt

Changing even a tiny part of that manifest would cause signature verification to fail.

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Second, the key that created the signature had this fingerprint: 4673 9B74 B56A D88F 14B0 882E C7EF 7090 0726 0119 which matched the SeedSigner project's published key.

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This authenticates the four SHA-256 hashes contained in the manifest.

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Add the authenticated hashes to this website

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Only after completing the authentication above were the four SHA-256 hashes added to the verification tool on this website.

The verifier therefore contains these authenticated values:

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pi0:
67f005c7ace26500a78be3f4d97eaf02d76d018550ec54df011741dde1933ce9

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pi02w:
f38237cdde39efca2fb9e3b3f9f8b0beff2248767f85289bd50657fa69b54f1f

 

pi2:
9fc7f2ea8462e1c9d62efe41301e12d559e8f155653913e33c93e905360bb813

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pi4:
3c2a11a2303abf2a73b10be913d44a1eb85d5e5a15b5389a670cb963afd1e28b

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They are not hashes that were calculated or supplied by us. They are the values contained in SeedSigner's v0.8.7 release manifest, whose PGP signature was independently checked before being added here.

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What happens when you use the verifier

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When you select a SeedSigner .img file using the verification tool on this website, your file is not uploaded anywhere. Your browser calculates the SHA-256 hash of the selected file locally on your computer. That calculated hash is then compared against the authenticated hashes listed above.

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For example, if you select the official Pi Zero 2 W image, your browser should calculate:

f38237cdde39efca2fb9e3b3f9f8b0beff2248767f85289bd50657fa69b54f1f

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If it does, the verifier displays: ✅ SeedSigner v0.8.7 Verified

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If even one bit of the downloaded image were different, its SHA-256 hash would be different and the verification would fail.

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The full chain of verification

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The process can be summarised as:

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SeedSigner signing key

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Fingerprint independently checked:

4673 9B74 B56A D88F 14B0 882E C7EF 7090 0726 0119

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PGP signature

seedsigner.0.8.7.sha256.txt.sig

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Good signature confirmed

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Authenticated checksum manifest

seedsigner.0.8.7.sha256.txt

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Authenticated SHA-256 hashes

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Your browser calculates the SHA-256 of your downloaded SeedSigner image

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The values are compared

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✅ SeedSigner image verified

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This allows users to perform the final verification with a simple file selector while the more technical PGP authentication of the expected hashes has already been performed independently.

Each time SeedSigner publishes a new software version, the new checksum manifest and developer signature must be authenticated again before the new hashes are added to this verifier.