Back up seed phrases and 2FA backup codes once: sealed in your browser, stored on-chain, and unlocked only by the security keys you hold.
Testnet preview. Your vault is encrypted on your device and stored on OP Sepolia, a test network, with an extra copy on Arweave when that upload succeeds. Test networks can be reset, and CryoShield has not been independently audited.
01 · The problem
Thumb drives, notebooks and hard disks wear out, get lost, or burn. Most backups of a seed phrase are one bad day away from gone.
Seed phrases often leak from the places people keep them.
LastPass, 2022. Attackers stole encrypted vault backups and are believed to have kept cracking weak master passwords offline for years. Blockchain analysts at TRM Labs estimate over $35 million in crypto thefts traced to it through 2025.
CryoShield has no master password to crack. Your vault key comes from a secret inside your security key that never leaves it.
Source: BleepingComputerSparkCat, 2025. Apps on the App Store and Google Play scanned photo galleries with text recognition, hunting for seed phrase screenshots.
CryoShield seals your phrase in your browser. Opening it takes a tap on your physical key.
Source: KasperskySlope, 2022. Security researchers reported that a wallet app sent seed phrases, unencrypted, to its error-logging server, in a breach that hit nearly 8,000 Solana wallets.
CryoShield encrypts before anything is stored or sent, and the code is open source, so anyone can check.
Source: The BlockOne honest limit: no backup can protect a phrase typed on a device that is already infected.
Testnet preview on OP Sepolia, not independently audited. Please keep your existing backups too.
02 · How it works
Tap your security key and it produces a secret only it can make, for this site only. Your browser uses it to lock your vault with AES-256-GCM before anything leaves your device. Only your keys can open it: CryoShield never sees your secrets or your keys.
03 · Where it lives
The sealed vault, about 1 KB, is written to a public blockchain (OP Sepolia during this test phase), and a copy goes to Arweave’s permanent archive. Anyone can see the locked data. Only your keys can open it.
Your secrets are locked on your device before anything leaves it. The keys that open them live in the security keys you hold, never with us or anyone else.
| Typical cloud storage | CryoShield | |
|---|---|---|
| Who can read your data | You, and the provider (who holds or can reset the keys) | Only you |
| Account and password to lose or have hacked | Yes | None |
| Can be frozen, deleted or shut down | Yes, by the provider | No: stored on a public blockchain and Arweave |
| Works if the company disappears | No | Yes: the open-source recovery tool reads it directly |
Some password managers also encrypt end to end. The difference is that CryoShield has no account, no servers holding your data, and no company you have to outlast.
04 · Resilience
You set up at least two keys, and any one of them opens your vault. Lost one? Open the vault with another and add a replacement.
If you lose every key, nobody can open the vault, not even us. There is no reset and no recovery service. Keep your keys in different places.
05 · Independence
An open-source desktop recovery tool opens your vault with just your key. It reads the vault straight from the public blockchain or Arweave, so it keeps working even if this website and CryoShield disappear.
06 · Time
Your vault stays readable as long as the blockchain or the Arweave copy exists, and at least one of your keys still works. Arweave is designed to pay for storage for at least 200 years. No one can promise any technology lasts that long, so keep your keys safe and check them now and then.
CryoShield pays the network fee each time your vault is saved, so you don’t need a crypto wallet or any cryptocurrency. You just need two security keys.
If fee sponsorship is ever paused, saving waits until it’s back. Opening your vault never depends on it.
Two security keys, one tap, and your seed phrase or recovery codes are sealed, stored, and yours alone.
Testnet preview on OP Sepolia, not independently audited. Please keep your existing backups too.
No backup lasts forever, but you can make yours outlive any one drive or sheet of paper. CryoShield seals your seed phrase in your browser, stores it on a public blockchain, and copies it to Arweave’s permanent archive. It stays readable as long as the blockchain or the Arweave copy exists and at least one of your keys still works. CryoShield is a testnet preview, so keep your existing backup too.
Somewhere that survives a lost phone or a dead laptop, and that only you can open. A CryoShield vault holds about 1 KB of text, enough for the 2FA backup codes of many accounts, and only your security keys can open it. While CryoShield is a testnet preview, keep a printed copy somewhere safe as well.
Two FIDO2 security keys that support the PRF extension (hmac-secret) and can be set to always ask for their PIN, such as a YubiKey 5 with firmware 5.2 or newer, and a recent version of Chrome, Edge or Firefox. The app checks your browser before you start. See supported devices.
No. Your secrets are encrypted in your browser with a key that only your security keys can produce. CryoShield has no backend; this website only serves the app’s files, and never receives your secrets or your keys.
Your vault is still safe. Open it with any other enrolled security key, then use “Add a key” to set up a replacement. That’s why you need at least two. If someone else may have the key and its PIN, read what to do if a key is lost or compromised.
Then nobody can open the vault: not you, not CryoShield, not the recovery tool. This is the cost of a backup that only you control.
Your vault stays on the public blockchain and on Arweave. The open-source desktop recovery tool can open it with your key, without this website.
CryoShield is a testnet preview on OP Sepolia and has not been independently audited. The code and the vault format are open source, and the encryption uses well-known open-source cryptography libraries (@noble) with published test vectors. Please keep your existing backups too.
About 1 KB of text: plenty for seed phrases, 2FA backup codes and recovery codes, but not for files.