How It Works
You verify that your recovery phrase is correct (correct words, correct order) securely by typing them into a verification program that runs on an air-gapped, offline computer, Offline Crypto's Verifier Computer. The verification program is the open-source bip39 verifier software, and the Verifier Computer is a Raspberry Pi Zero 1.3. (See the Open Source page for more info).
The Raspberry Pi Zero 1.3 computer has no wireless or bluetooth, etc. capabilities, reducing the possibility of an inadvertent Internet connection to zero. And the user never connects it to the Internet. Crucially, that way, the recovery phrase cannot be stolen (via hacks, or phishing, and so forth) over the Internet.
If you need help using the recovery phrase verifying software from someone physically present who could see your screen, don't worry, you are covered! A prominent checkbox near the top of the screen lets you hide all private data with a single click of the mouse.
The Raspberry Pi Zero 1.3 computer has no wireless or bluetooth, etc. capabilities, reducing the possibility of an inadvertent Internet connection to zero. And the user never connects it to the Internet. Crucially, that way, the recovery phrase cannot be stolen (via hacks, or phishing, and so forth) over the Internet.
If you need help using the recovery phrase verifying software from someone physically present who could see your screen, don't worry, you are covered! A prominent checkbox near the top of the screen lets you hide all private data with a single click of the mouse.
The Safest Way
When the recovery phrase has been verified, the included sd card (the memory card) can be destroyed and disposed of properly. Or, the sd card can be securely bit-shredded. Offline Crypto's Verifier Computer, a Raspberry Pi Zero 1.3, has no built-in memory, so outside of the sd card, nothing can retain a record of the recovery phrase. Of course, for simplicity, a user can also just destroy the whole computer, disposing of it properly. That way, there's no need to open the computer up in order to remove the SD Card.
Compared to setting up an old laptop or desktop to do the verification, Offline Crypto's Verifier Computer offers complete security from Internet-based attacks: It has no firmware or other non-volatile memory outside of the SD Card; it has no bluetooth, wifi, or other wireless capability, thus eliminating the possibility of an inadvertent or malicious Internet connection over which your recovery phrase could be stolen; it has no Ethernet (wired Internet) connection, thus eliminating the other way that your recovery phrase could be exposed to the Internet; and its non-volatile memory is completely contained in one single, inexpensive, easy to destroy, easy to bit-shred unit, the SD Card.
Also, consider: What if someone connects the old laptop or desktop, that you had used to verify your recovery phrase, to the Internet, thus potentially exposing your recovery phrase to theft? The Crypto Verifier computer cannot accept a wired or wireless Internet connection and its only memory unit can be easily destroyed. The same cannot be said for the old desktop or laptop alternative.
Compared to setting up an old laptop or desktop to do the verification, Offline Crypto's Verifier Computer offers complete security from Internet-based attacks: It has no firmware or other non-volatile memory outside of the SD Card; it has no bluetooth, wifi, or other wireless capability, thus eliminating the possibility of an inadvertent or malicious Internet connection over which your recovery phrase could be stolen; it has no Ethernet (wired Internet) connection, thus eliminating the other way that your recovery phrase could be exposed to the Internet; and its non-volatile memory is completely contained in one single, inexpensive, easy to destroy, easy to bit-shred unit, the SD Card.
Also, consider: What if someone connects the old laptop or desktop, that you had used to verify your recovery phrase, to the Internet, thus potentially exposing your recovery phrase to theft? The Crypto Verifier computer cannot accept a wired or wireless Internet connection and its only memory unit can be easily destroyed. The same cannot be said for the old desktop or laptop alternative.
The Operating System
With Offline Crypto's Verifier Computer, you will be running the latest, most secure software, as it ships with the latest available Raspbian Operating System, an open-source Linux operating system that is a sub-flavor of the enormously successful open-source Debian Linux operating system. (See the Open Source page for more info). The latest release is always available from the Replacement SD Card page.
Protection Beyond Verification
Offline Crypto's protection of your recovery phrase goes beyond verification: You use the kit's engraving tool to easily and quickly engrave your newly-verified recovery phrase into steel plate, so that the recovery phrase has a high degree of protection against physical damage such as fire or mechanical damage. The process is just like writing with a pen, only with safety glasses. ;)
Compatibility
Will the Verifier Computer work with your hardware wallet and your crypto? See the full support list.
Wallets: It has been tested with the Ledger hardware wallet (2018), the Trezor hardware wallet (2018), and the KeepKey hardware wallet (2018). Other hardware wallets may or may not work with it. If you have even one kind of crypto that works with the verifier, that is all you need to verify that your recovery phrase is correct for these wallets.
Cryptos: Please note that, while this has been tested on the Ledger hardware wallet with the BitCoin (btc), BitCoin Cash (bch), Ethereum (eth), Ethereum Classic (etc), LiteCoin (ltc), Dash (dash), Ripple (xrp), and ZCash (zec) receive addresses, and tested on the Trezor hardware wallet with LiteCoin (LTC), and should work with many or all of the major cryptocurrencies, no guarantee is made.
Wallets: It has been tested with the Ledger hardware wallet (2018), the Trezor hardware wallet (2018), and the KeepKey hardware wallet (2018). Other hardware wallets may or may not work with it. If you have even one kind of crypto that works with the verifier, that is all you need to verify that your recovery phrase is correct for these wallets.
Cryptos: Please note that, while this has been tested on the Ledger hardware wallet with the BitCoin (btc), BitCoin Cash (bch), Ethereum (eth), Ethereum Classic (etc), LiteCoin (ltc), Dash (dash), Ripple (xrp), and ZCash (zec) receive addresses, and tested on the Trezor hardware wallet with LiteCoin (LTC), and should work with many or all of the major cryptocurrencies, no guarantee is made.
Verify As Many Recovery Phrases As You Like
The Verifier Computer will verify as many recovery passphrases as you want to verify. Have more than a single hardware wallet? No problem. Have friends and associates who have not verified or protected their recovery passphrases? You are good to go to help them get verified and protected. Want to offer a recovery phrase verification and protection service? This will work perfectly.