The home page says the cipher lets you carry a seed phrase across any border. This page is about what the border is actually like, with the United States as the worked example because it publishes numbers. The law varies by country and changes; this is a description, not legal advice, and if you have a real question you need a lawyer in the country you are entering.
How often devices get searched
U.S. Customs and Border Protection publishes its counts. In fiscal year 2025 it searched 55,318 travellers' electronic devices. About 92 percent were "basic" searches and about 4,400 were "advanced." CBP says that was under 0.01 percent of arriving international travellers, and about 0.47 percent of the people sent to secondary inspection. The first three quarters of fiscal 2026 had already reached 52,081.
So the odds on any one trip are small. The consequences when it happens are not, which is why the setup should assume it will.
Basic and advanced
CBP's directive 3340-049B draws the line:
- A basic search is an officer looking through the device by hand. No suspicion is required.
- An advanced search is one where the officer connects equipment to copy or analyse the contents. It needs reasonable suspicion and a senior manager's approval, and it is the one that produces a forensic image.
Either way, the officer asks you to unlock the device. Policy says they examine what is on the device, not what is in the cloud, and devices are supposed to be put in airplane mode first. A wallet app, a photo of a seed, a notes file, a password manager: all of that is "on the device."
What you can be made to do
For U.S. citizens, the Electronic Frontier Foundation's border guide is the clearest statement: you cannot be denied entry for refusing to unlock a device. You can be delayed, questioned at length, and your device can be seized for examination. The guide says seizures shouldn't normally run past five days, that extensions of weeks or months are common, and that you should ask for a property receipt, Form 6051D. Non-citizens, including permanent residents in some circumstances, have less room; refusing can mean being turned away.
Passcodes and biometrics are treated differently. The EFF's position is that the Fifth Amendment protects you from being compelled to state a password, because a password is the contents of your mind. Some courts have held that a fingerprint or a face is not protected in the same way, because it reveals nothing you know. The EFF's practical advice follows: use a passcode, not a fingerprint or a face, on anything you carry through a border, and power the device off before you reach the line, since most phones require the passcode after a restart.
Wherever you are, the same split applies to a seed phrase. Words on a device are found by a search. Numbers on a receipt are ignored by one. Words in your head can only be had by asking, and in some countries the asking can be very persistent, which is the subject of the wrench page.
What crosses well
The question to ask of everything in your bag: if an officer picks this up and looks at it for thirty seconds, what does it look like?
A phone with a wallet app looks like a wallet. Even with no funds in it, the app shows that you hold bitcoin, and the transaction history shows how much. The app may hold the seed in its own storage. Leave the wallet app at home, or travel with a phone that has never had one.
A hardware wallet looks like a hardware wallet. Small, recognisable, and the obvious thing to ask you to unlock. If you travel with one, it should hold the decoy, and the real wallet should be behind a passphrase that is not on you.
A photo of a seed is the worst case. It is on the device, it is in the backups, it is what a basic search finds in the first minute.
Metal plates with twenty-four words are a seed phrase to anyone who has seen one before, and officers at busy ports have.
A list of numbers on paper, in the format of a receipt, a packing list, or a weight log, looks like what it is dressed as. There is no app to open and nothing to unlock. That is the whole idea behind the cipher, and it is why the procedure says to remember the cipher's name and not carry the cipher itself: the tomes are public, and the one in your bag would be the thing worth asking about.
Hiding is not encrypting. The ciphers are public and a seed phrase carries its own checksum, so a list someone recognises as a seed can be tried against every cipher in minutes. At a border, an officer who recognises the list can copy it. The passphrase, kept in your head or on the far side of the border, is what makes the copy worthless.
A travel setup
- Nothing bitcoin-related on the phone or laptop you carry. Not the app, not the vendor's email, not the browser history. Wipe or use a travel device.
- The seed, as cipher numbers, disguised, on paper, or not with you at all. The cleanest trip is one where the numbers are already waiting at the other end: posted ahead, held by a person, or stored online in a form that only means something with the cipher name and passphrase you know.
- The passphrase in your head, and nowhere in the bag.
- If you carry a hardware wallet, carry the decoy and expect to be asked to unlock it.
- Devices powered off, passcode not biometrics, backups disabled for anything you wouldn't want imaged.
- Nothing to lie about. "I don't have a wallet with me" should be true.
We will never ask for a seed word or a passphrase. Never type one into this site or any tool it links to. Nobody at a border has a reason to ask for one either; if they do, that is a question about the law in that country, not about your wallet.
Sources
- Border search of electronic devices, U.S. Customs and Border Protection, with the fiscal-year counts and the basic/advanced definitions from Directive 3340-049B
- Digital privacy at the U.S. border: protecting the data on your devices, Electronic Frontier Foundation
- The five-dollar wrench, on being asked more persistently