Unboxing: What's Included in the SeedSigner Kit
The SeedSigner kit can be purchased from $BTC Hardware Solutions (worldwide shipping), GoBrrr or DIYNodes (EU/U.K.), or TechHaven (Philippines). It includes: Raspberry Pi Zero, Raspberry Pi camera module, ribbon cable, WaveShare LCD HAT display, 3D-printed open-face case, seven blank QR code/mnemonic phrase cards, SeedSigner sticker, Getting Started instructions, and a Thank You card. You need to supply a MicroSD card (at least 4 GB) and a micro USB cable. The blank cards measure 64 mm × 89 mm, with 24 blank spaces for seed words on one side and a 29×29 QR code grid on the other, both with warnings against entering seed words into internet-connected devices. Alternatively, stainless steel backup plates (3 mm × 66 mm × 91 mm) from @SeedMint21 (Vulcan21.com) can withstand fire and flooding; they feature a 29×29 grid that you mark with a marker and then stamp permanently with a punch.
Software: Downloading and Flashing the Image
Download the latest SeedSigner .zip release from the GitHub repository along with the corresponding .sha256 and .sig files. Verification is recommended: Windows users can use Kleopatra (from gpg4win) to import the SeedSigner public key, certify its fingerprint (compare to the public Twitter profile), and then verify the .sig file. A green dialog means valid and certified; white means valid but not certified; red means invalid. After verifying the .sha256 file, compute the SHA-256 hash of the .zip file using a tool like HxD and compare. Linux users can import the key via curl and gpg --import, verify with gpg --verify, and check the hash with shasum -a 256 -c. Then use Balena Etcher to flash the .zip directly to the MicroSD card. The software handles decompression, flashing, and validation. Safely eject the card when done.
Hardware: Component Details, Testing, and Assembly
Test the hardware before final assembly to avoid damaging the 3D-printed case. The camera is a 5MP OV5647 sensor (30 FPS, 2592×1944 resolution). The Raspberry Pi Zero v1.3 has a 1 GHz single-core CPU, 512 MB RAM, mini-HDMI, two micro USB ports (one for power, one for data), a 40-pin HAT header, and a CSI camera connector. The WaveShare LCD HAT is a 65×30 mm display with 240×240 RGB resolution, controlled by a joystick and three buttons. To test: release the camera connector tab, insert the ribbon cable (gold connectors down), insert the MicroSD card, loosely attach the LCD display, connect power, and wait ~45 seconds. Test joystick, buttons, and camera. Shut down, then assemble: remove camera film, snap camera into the case, insert Raspberry Pi Zero (USB ports aligned), reinsert MicroSD, and press the LCD into place. Re-test.
Generating a New Seed: Camera or Dice Method
The master seed is a random number used to derive all keys. SeedSigner offers two entropy sources: Camera – captures multiple frames before the image, combines them with the Pi's serial number and uptime in milliseconds. Navigate to Seeds → + Create a seed → camera icon, take a unique photo, accept, choose 12 or 24 words, acknowledge the warning. Dice – each six-sided die roll provides ~2.58 bits of entropy; 128-bit security requires 50 rolls, 256-bit requires 99 rolls. Navigate to Seeds → + Create a seed → dice icon, choose word length, roll and enter each result. After the last roll, the mnemonic appears. SeedSigner can also calculate the checksum (12th or 24th word) from the first 11 or 23 words. It can import an existing mnemonic phrase (12 or 24 words) by letter-by-letter selection; incorrect checksums trigger a warning.
Seed Backup: Mnemonic Phrase and QR Code (Paper and Steel)
Immediately after generating a seed, back it up. Two methods: Mnemonic backup – write the words in order on the paper card (four at a time), then take the self-test. QR code backup – from the main menu go to Backup Seed → Export as SeedQR → Begin 29x29. SeedSigner shows the QR code in magnified segments; use a permanent marker to fill in the dark squares on the card's grid. The error correction tolerates minor mistakes. Test by scanning and verifying the fingerprint. If you use a passphrase, note both the primary wallet fingerprint and the passphrase-applied wallet fingerprint (mark “PP”). Store the passphrase separately from the mnemonic. For extra durability, use a stainless steel plate: mark the dark dots with a marker, test with SeedSigner, then stamp permanently with a punch and hammer. A fire test (up to 1500°C) showed that although the plate becomes oxidized and cannot be scanned directly, the QR code can be manually transcribed to paper and then scanned with 100% recovery.
Sparrow Wallet: Importing a Watch-Only Wallet and Signing PSBTs
SeedSigner keeps private keys offline. In Sparrow Wallet, go to File → Import Wallet, select SeedSigner as the device, and click Scan. On SeedSigner, scan your seed QR code, enter passphrase if any, go to Export Xpub, choose Single Sig and script type (e.g., Native Segwit), select Sparrow Wallet, and confirm. Animated QR codes appear; hold them to your PC webcam. Name the wallet and optionally set a password (different from your passphrase). The wallet syncs and shows “Receive” addresses. To spend, create a PSBT: select UTXOs, enter address, amount, fee, click Create Transaction → Finalize Transaction for Signing → Show QR. Scan with SeedSigner, verify details (amount, change, address), approve and sign. The SeedSigner displays signed PSBT as animated QR; scan it in Sparrow and click Broadcast Transaction.
Importing Private Key into Sparrow (Warning: Creates Hot Wallet)
From Sparrow version 1.6.4, you can scan the SeedSigner's private key QR code directly. This puts your private key on a networked device – only do this if you accept the risk of a hot wallet. Steps: File → Import Wallet → Mnemonic Words → Scan QR, point camera at SeedSigner's private key QR, enter passphrase if any, click Discover Wallet, name the wallet, optionally set password. After import, you can quickly generate addresses, construct and broadcast transactions, and use PayNym or Whirlpool. Encrypting the wallet file is a minimum precaution.
Multisig Wallet: Using Multiple SeedSigners
SeedSigner supports multisig with Sparrow. Generate seeds for each participant (e.g., 4 seeds for a 4-of-4). In Sparrow, File → New Wallet → name it → policy type “Multi Signature” → set M-of-N (e.g., 4-of-4). For each cosigner, select “Airgapped Hardware Wallet” → Scan, then on SeedSigner export Xpub (Multisig, Native Segwit, Sparrow). Scan the animated QR. Repeat for all cosigners. Click Apply. You can optionally password-encrypt the wallet. To spend, create a transaction in Sparrow and generate the PSBT QR; load each cosigner seed into SeedSigner, scan the PSBT, sign, and present the signed QR back to Sparrow. Repeat for the minimum number of cosigners required, then broadcast.
The Importance of Self-Custody
“Not your keys, not your coins” highlights why self-custody is critical. Relying on exchanges exposes you to theft, seizure, forced liquidation, and KYC requirements. SeedSigner's open-source, DIY approach combined with air-gapped operation minimizes trust in third parties. Whether you're a beginner or an advanced user, building your own signing device is a fundamental step toward true financial sovereignty.