How to Store a Crypto Seed Phrase Safely (Offline First)

Store a crypto seed phrase offline: write it by hand on paper or stamp it into metal, check every word, and keep copies in at least two secure physical places. Don't photograph it, don't screenshot it, and don't type it into a cloud note, email, or website. A phone can play a supporting role, but it shouldn't be your primary backup, and a photo in your Camera Roll is one of the riskier places a seed can end up.

This guide is about self-custody wallets that use a 12- or 24-word recovery phrase (BIP-39). If someone gets those words, they get the funds, and transactions can't be reversed. That's why the bar here is higher than for anything else you keep on your phone.

Step 1: Write it down correctly

When your wallet shows the seed:

1. Be somewhere private. No cameras, no screen sharing, no one looking over your shoulder.
2. Write each word by hand, numbered, in order. Use clear block letters.
3. Double-check the spelling against the wallet's screen. BIP-39 words are uniquely identified by their first four letters, which helps catch mistakes.
4. Complete the wallet's verification step honestly; don't skip it.
5. Do a recovery test. With a small amount in the wallet, wipe or reset it and restore from your written seed. If it restores, your backup works. Do this before you move serious funds in.

Step 2: Choose a durable medium

Paper is fine to start with but vulnerable to fire, water, and fading. Use acid-free paper and a pencil or archival pen, and store it in a sealed bag.

Metal backups (stamped steel plates, or tile-and-letter kits) survive fire and flood. For significant amounts, they're worth the cost. Buy from a reputable seller, and assemble it yourself, privately.

Avoid: laminating (traps moisture, can melt), printers (some keep copies), and anything that requires electricity to read.

Step 3: Store copies in more than one place

A single copy is a single point of failure. Common setups:

• Two copies, two locations. Your home safe and a trusted family member's home, or a bank safe deposit box.
• Hidden in plain sight. Not labeled "crypto seed." A sealed envelope among other papers draws less attention than a box marked "wallet."
• Tell someone how to find it. Not the words themselves, but that it exists and where, in case something happens to you. Estate planning for crypto is its own topic, but don't let your funds become unrecoverable by accident.

Step 4: Consider a passphrase

Most wallets support an optional BIP-39 passphrase (sometimes called the "25th word"). With it, the seed alone isn't enough to open the wallet; someone also needs the passphrase. That protects you if a seed backup is found.

The trade-off: if you forget the passphrase, the seed alone won't restore your funds. Store the passphrase separately from the seed, never on the same paper or plate.

For larger holdings, multisig setups and Shamir backups (splitting the secret into shares) remove the single point of failure entirely. They add complexity, so learn them with small amounts first.

Why a photo on your phone is risky

People photograph their seed because it's easy and the phone is always with them. Here's what happens to that photo on a typical iPhone:

• It syncs. With iCloud Photos on, it's uploaded and appears on every device signed in to your Apple Account. Unless Advanced Data Protection is on, Apple holds the encryption keys.
• It's searchable. Photos recognizes text in images. Searching for a common seed word can bring it right up.
• Other apps may reach it. Any app you've given full photo library access can read your library. Security researchers have found malicious apps, including some that made it into official app stores, that scanned photo libraries with text recognition looking for recovery phrases.
• It opens with your passcode. Even in the Hidden album, it's one passcode away for anyone who learns it, including a thief who watched you unlock your phone.
• It persists. Deleted photos stay in Recently Deleted for 30 days, and may also exist in device backups.

Screenshots have all the same problems. Notes and email add server-side copies.

If you have a seed photo on your phone right now, the safest move is: write the seed down on paper or metal, verify it, then delete the photo from Photos and Recently Deleted, and check that it's gone from iCloud and backups. If you think it was ever exposed, move your funds to a new wallet with a new seed.

If you keep a digital copy anyway

Some people decide a digital copy is worth having as a secondary backup, for example while traveling. If you do, reduce the risk as much as you can:

1. Keep an offline paper or metal copy as the primary backup. The digital one is secondary.
2. Keep it out of Photos, iCloud Photos, Notes in iCloud, and email.
3. Encrypt it with a secret that isn't your phone passcode, so unlocking the phone isn't enough.
4. Don't sync it anywhere. Local only.
5. Consider storing only part of it, or the seed without the passphrase, so the digital copy alone can't open the wallet.

An encrypted vault fits points 3 and 4. sigil. encrypts files on the device with a 256-bit key that only the sign you draw on a 5×5 grid can unlock, has no account and no server, and doesn't sync. The private camera captures directly into the vault, so the image never touches the Camera Roll, iCloud Photos, or Photos search.

To be clear about the limits: a digital copy on a phone is still more exposed than a metal plate in a safe. A compromised device, a weak sign, or someone watching you draw it can all defeat it. We'd use it for a secondary copy of a modest wallet, not as the only backup of your savings.

What not to do

• Don't type your seed into any website, form, or "wallet validator," and don't share it with anyone who claims to be support. Real support never asks for it.
• Don't store it in a password manager that you also use on shared or work computers.
• Don't email it to yourself or put it in a cloud document.
• Don't split words across apps and call it secure; it's harder for you and not much harder for a determined attacker.
• Don't rely on memory alone.

Your phone's own role

Your phone is probably the device that holds your hot wallet. Protecting the phone protects the wallet:

• Use a strong alphanumeric passcode: Settings > Face ID & Passcode > Change Passcode > Passcode Options.
• Turn on Stolen Device Protection in the same screen.
• Review apps with Full Access to Photos in Settings > Privacy & Security > Photos.
• Know what to do if the phone is lost; see how to protect photos if your phone is stolen and the lost or stolen phone scenario.

Related: recovery phrases in general

Crypto wallets aren't the only apps using recovery phrases. sigil. itself gives you a 12-word recovery phrase from the same BIP-39 wordlist, to unlock your vault if you forget your sign. The advice above applies to it too: write it on paper, store it offline, don't photograph it. What is a recovery phrase? explains how they work. If you're curious why encryption keys are so strong and the human backup is the weak point, see AES-256 encryption explained.