Bitcoin Forum

After the discussion in this thread (https://bitcointalk.org/index.php?topic=5490813) I started thinking about ways to solve the problem of storing and safely transporting seed phrase when traveling to other countries.

Here I want to discuss factory-made electronic devices (as the most accessible for a wide range of users and at an affordable price), which can be taken with you almost anywhere and not arouse suspicion (minimizing the attraction of attention) that seed phrase are stored in these devices. Of course, not as a main backup (for these purposes it is better to look at topic (https://bitcointalk.org/index.php?topic=5389446.0)), but an additional, backup one in case you somehow lose access to your how wallet or hardware wallet (for example, resetting to factory settings).

An important criterion that I highlight is the autonomy of the device (autonomous power supply), the presence of a display, a keyboard for entering text (not in all cases), the lack of mobile communications and the Internet (for this reason I will not consider smartphones and tablets) and, if possible, minimizing the connection to PC (as a possible source of penetration of malicious programs) – lack of various information input interfaces (ports), as well as compactness (so that it is not problematic to carry with you in a backpack).

All links are provided for informational purposes only.

1. Electronic Diary from Citizen (https://www.ebay.com/itm/166682336832) (may be the closest analogue from any other company).

https://www.talkimg.com/images/2024/04/20/j7QVa.th.png (https://www.talkimg.com/image/j7QVa)

Price: 10 - 20$.

Peculiarities:
- Availability of a monochrome display;
- Keyboard;
- Memory 128\256 kb;
- Battery;
- Availability of a password to access data;
- The absence of any connectors, which makes it impossible to steal information from it, other than physical theft. (I would look at those who would steal such a useless rarity these days :)).

Possible disadvantage:
- If the device is de-energized (remove the battery), all data will be deleted. In principle, this can be used for emergency data deletion. The same thing will happen if the battery runs out.

2. Multifunctional calculator (https://www.aliexpress.com/item/4000053507938.html?sku_id=10000000120015282) from Chinese noname AIRCHR.

https://www.talkimg.com/images/2024/04/20/j7tzW.th.png (https://www.talkimg.com/image/j7tzW)

Price: unknown.

Peculiarities:
- Availability of color display;
- Keyboard (without text);
- Memory 4 GB + memory card ;
- Battery (900mAH);
- Supports images (JPEG, BMP, GIF);
- Reading text documents;
- Supports Audio and video (MP4, AVI, AMV, WMA, WAV, MP3);
- Privacy Special Function.

Possible disadvantage:
- Supports USB charging and data transfer. Files in image or text format will have to be downloaded to the device from a PC, which may turn out to be a potential attack vector during which the seed phrase can be compromised on the PC (this is not a threat on this device).

3. Watch with e-book (https://www.aliexpress.com/item/32970550622.html) reading function again from AIRCHR (there can be any with a similar function).

https://www.talkimg.com/images/2024/04/22/jKLj3.th.png (https://www.talkimg.com/image/jKLj3)

Price: ~30$.

Peculiarities:
- E-Book Reading, Photo Viewer (JPEG, BMP, GIF);
- Audio / Video Format Support (MP3, WAV, AMV, AVI);
- Lithium Battery (> 20 hours);
- Memory 8Gb;
- Emergency Button;
- Privacy Screen;
- No need to install any tools.

Possible disadvantage:
- Supports USB charging and data transfer.  

4. Electronic Dictionary from Casio (https://www.ebay.com/itm/395320614365).

https://www.talkimg.com/images/2024/04/22/jKcOw.th.png (https://www.talkimg.com/image/jKcOw)

Price: ~30$.

Practically not much different from Electronic Diary.

Peculiarities:
- Handwriting Panel (enables writing and searching);
- Read-aloud Function (capable of reading text aloud);
- Battery (2 x AA alkaline batteries ~ 130 hours);
- Memory card type (microSD, microSDHC);
- Built-in memory (ROM) 50 Mb;

Possible disadvantage:
- Supports USB charging and data transfer.

Seed phrase can be placed (separately) in the text of any book, the main thing is not to forget their location (leave stamps).

Don't accidentally enable voice playback of text with seed phrases. :)

5. MP3 player from Sony (https://www.ebay.com/itm/176341007302).

https://www.talkimg.com/images/2024/04/22/jK9uo.th.png (https://www.talkimg.com/image/jK9uo)

Price: ~ 30$ (many may have kept this device from old times).
 
Peculiarities:
- Memory 4 Gb;
- Playable Media Format (MP3);
- Battery (can be either built-in or external AAA format).

Possible disadvantage:
- Supports data transfer or USB charging.

You may ask me how to write seed phrases on a device that is not capable of reading text files or pictures. The answer is simple. The player has a display showing track names. Seed phrases can be written into track titles.

Can you use these devices for encrypting the seed phrase on the memory card?

You can do it on a device that is airgapped. But if you have online wallet which can be good for frequent transaction and just for holding small amount of bitcoin, connecting it to online laptop should not be a problem if you are protecting your laptop from malware and hackers very well.

With two or three memory card which I can put on a memory card adapter. Only one adapter. Or to get two or three small size flashdrive. Or to get two or three small size disk. Or get one of each or anyhow that I want it but in a way that I will have more than one backup. I can use any of them to encrypt the seed phrase and carry it along with me while traveling. If possible I am still traveling back, I will also leave backups at home.

Wouldn't it be easier to encrypt wallet file using a strong password and passpahre, store them separately in a USB or any device and then recover them using an airgapped PC or you can even use an encrypted passpahre and leave the 12 words as they are with a small balance like $100?
Electronic Diary does not contain encryption, does not have shock protection, and the code is closed source.

I guess not.
Your question led me to a possible vulnerability (but not certain) in this device. Is it possible to copy data (maybe not) from the calculator to a memory card? But the question of who would think of trying to copy data from a calculator remains relevant.

It seems you didn't read my first post on the topic at all. Read it again please.

A flash drive arouses the curiosity of strangers about the contents of this device, even if the data there is encrypted.

You can come up with many solutions for storing and transporting phrases on devices (and not only). Flash drives, airgapped devices, etc. are beyond the scope of the topic that interests me, but not beyond the scope of possible solutions for storing seed phrase.

The reasons that prompted me to consider exotic methods are indicated in the first post.


Electronic Diary doesn't contain encryption and theoretically, if you have physical access, you can obtain data from this device if you manage not to turn off the power to the device during disassembly (a reset will occur).

That's right, the device is not protected from shock, fire, acids, floods, hurricanes and volcanoes, as well as any other influences. This device is intended for temporary, non-primary storage.

True, this is closed source, but I wanted to ask you. Let's say there are backdoors (on a 20-year-old device), then how will the data stolen by them leave this device without a wireless connection?

This is a reason it should not be used. But some people may prefer to passphrase their seed phrase which can give a good option for its use. As for me I can not use it. I will prefer encrypted flashdrive, memory card or disk which I have talked about before.

You are right about this. If it has no way to connect online and it is thoroughly checked and see that it can not connect online, we do not need to talk about if it is open or close source as it will stay permanently offline.

Regarding digital methods for SEED backup storage.

I use for this purpose bootable  flash drive that holds Tails with blocked communication drivers and persistent volume locked by composite password part of which is on hardware security key which holds also my pgp key.

Persistent volume holds database for KeyPassXC locked again by composite password (that includes part of HW security key)  which differs from password used to unlock   persistent volume.

In turn, KeyPassXC database holds gpg message relevant to my SEED phrase. This message  encrypted by my HW pgp key (smart card) which is protected by PIN. Only two wrong PINs are allowed. The third wrong attempt will block access to pgp key.

Such setup allows me to get my SEED virtually on any device (including hybrid laptops with e-ink display) which is clear for Tails use.

P.S. This  sophisticated technique  accompanies my primitive  one which is  based on both  paper and metal washers.

I think that those devices that you shared, look suspicious, especially if I saw them in the hand of young man. And I don't understand what's wrong with having a paper wallet with you in the airport? Who is gonna check paper? And who is gonna steal it from you? Or probably bring an air-gapped smartphone with you where you store your wallet but nothing beats paper in this case for me. Also, I don't think someone wants to take keys of cold storage with them when they travel, not in a secondary backup way at least. So, I assume that when we travel, we want to have a hot wallet with us, right? Just be sure that your smartphone is clean, install Electrum in it and travel that way or as I said previously, get a paper wallet and done.

I just checked the link and the page says that device has price 9067 RUB or about 97 USD.


But i wonder how many people would put random/unknown flash drive to their device these days. After all, it may contain malware or send high voltage in attempt to break your device.

Corrected the link.

At that time (when I saw this device), the price was not displayed due to the fact that all devices were sold out. Probably the seller has a new supply of goods and therefore he has put up a price tag.
The price may vary due to discounts and is currently ~￡43 (about 2 times less than what you specified).


Determining the degree of suspicion is a very subjective thing.

And not in the hands of a young man, but in a backpack (baggage). There is no need to demonstrate such gadgets publicly unless you have an electronic notebook and a calculator in your smartphone.

And when crossing customs officers or a police search, what business is it of theirs what a person is interested in (old gadgets), if it doesn't violate any laws.

You have the right to do as you think is right. I would prefer to discuss within the framework of the concept that I described.

I see. Anyway while i find￡43 is cheap for such new device, that amount of money also enough for few hardware wallet (such as Blockstream Jade which cost $40).


At least for custom officer on some country, vague "reasonable suspicion" and random inspection are fairly common reason to go through all your devices.

The lack of encryption means that if a friend next door or at the airport notices it, will try to read it. Humans love to snoop and read other people's diaries, and the old design may attract attention.

Some of these devices contain a USB port, which is sufficient to transfer data, especially since the programming of these devices is old and we are talking about unencrypted text content.

I think that some old multifunctional calculator is capable of storing 12 words without USB port and burned code, with the ability to hide them easily. it will be Best option

I have used this type of calculator in my high school days. I could remember while so many others were using it for mere arithmetic, I and my friends were using it to save data such as mathematical formulas. This gave us some undue advantage over them. Using it to transport seed phrase is a thoughtful idea, but the simplicity of the process is in doubt.

This brings me to what synchronice said
Even if not within the scope of this discussion, using paper to pen down the seed phrase with an airgaped device for travel purposes is not a bad option.

If you travel a lot, you already probably know that some customs are racists, moody and love when they mess with you. If you are EU citizen and travel inside EU, everything goes smoothly but outside of EU, it's a little bit headache to my mind. I personally wouldn't risk traveling with such a device in Australia, their customs are one of the strictest ones.

Don't get me wrong, I would love to discuss within the framework of your concept but I don't understand the pros of your idea and I'm trying to find one. I am sure it's never a good idea to bring additional electronics in airport if you want to safely pass the check. To be honest, I love the idea of Smart Watch and MP3 player, it's very creative to write tracks on your MP3 player and name them like seed phrases.

I found one old Casio G-shock watch that could work very good as device for storing seed words, but this should not be used for storing large amount of coins.
Exact model of watch is G-Shock G-2900, it was released back in year 2002 and it not manufactured anymore, but it can be purchased as used device.
G-2900 have one of the largest data memory from dumb casio watches, and this can be used as offline storage for keys and any other text, with additional password protection.
This watch is perfect for traveling, it is very durable, hard to destroy, and it won't bring much attention from anyone.

There was also one hardware wallet BITHD Watch 2 that looked more like modern smart watches, but it is not produced anymore and Bithd website is down.
It would be interesting to have more hardware wallets in form of wrist watches.

https://www.talkimg.com/images/2024/04/29/rmg7P.png   https://i.ibb.co/wgjZY8K/BITHD-watch-2.jpg

It was your mention of G-shock that prompted me to think about this method of storing seed phrases.


The concept of large or small quantities of coins is different for everyone, but one can argue that such methods of storing cryptocurrencies should not be used as the main and long-term one.

Curious, does Casio (or another) produce watches with memory cells now? Smart watches are not considered

This watch model (e-DATA memory) can store up to 40 records.

"of 7 characters each, or more or less records depending on the number of characters used for each record"

source: https://www.g-central.com/specs/g-shock-g-2900/

What memory does this watch use? Autonomous? If the battery is removed, discharged (as the manufacturer assured, the battery life is 10 years :)) or is damaged due to physical impacts, then the internal memory data will probably disappear forever.

Of course, this watch looks like one of the best solutions as an e-device for storage of seed phrases, because it is always at hand.

Yes, I also like this idea, but with some modernization (for an amateur): HW watch should look something like a G-shock, which normally works like a watch, but as a “second bottom” it is used as a hardware wallet (connecting to a PC via USB). Although, tailoring the hardware wallet to a smartwatch also looks good (I'm sure this product could be more widespread). It seems to me that generating a QR code and displaying such at watch on the display to confirm a transaction (for example, scaning it from a smartphone camera) would be a good solution.

How about an old keypad mobile or even a new one without inserting sim cards be considered for this purpose?

I can find some keypad mobiles that are brand new and available for under $50 - and  $40 can do the job.

Availability is everywhere, we do not need to worry about the data stored getting deleted like calc and data dictionaries.

Advantage of using a watch is that you can easily have it on your wrist, and almost nobody would suspect what you have hidden inside it.
I have been trying to find other wristwatches that could be work in similar way, without being a smart watch, but no luck so far.
Maybe that is not a bad thing, there are plenty of G2900 available in Japan and worldwide.

As far as I know there are no more G-shock models in production that have Data Memory.
There are other models but they have smaller memory compared to G-2900.
You can check them all here:
https://shockbase.org/function_page_dyn.php?function=data_memory

There are several Casio Databank models but I am not sure how big their memory is:
https://en.wikipedia.org/wiki/Casio_Databank
https://www.casio.com/us/watches/casio/databank/

They use cheap CR2025 battery that lasts for years with no problem, but when removed it's all gone, that could be a good thing also ;)
Casio gave it 10 year rating, but people say it lasts longer if you don't play with watch and light all the time.

This seems to be a good idea if you ask me, the old ones do not have any internet connections and only come to live as when a SIM card is inserted, they can be used for the purpose as you can save messages as text on drafts. They are definitely below the $40 price. My only problem is you cannot switch them off for a very long time as they usually run into ba3 problem but it’s a good option.

I assume you're concerned about battery life, I used nokia that can lasts for days even with intermittent usage but he all it needs standby or even turning off and on won't be a problem which makes it highly reliable option in my perspective. I don't know the new era keypad mobiles are coming with removable batteries, if they do then I don't see any problem with them.

Theoretically, this is possible, but practically, being paranoid, I would think about this solution 10 times. :)

The fact is that the main function of a SIM card is subscriber authentication in the cellular network. That is, even without a SIM card, the phone can work (with some reservations), for example, calls to emergency numbers, like 911 (which are most often built into the GSM standard).

And I can find it completely free in a box of old mobile phones in my closet. :)

This is undoubtedly an advantage, as is the ability to add a password to access phone data.


Old phones, unlike new Chinese push-button phones, don't have built-in backdoors and dubious apps that send data to their servers, therefore, it is better to use older mobile phones.

The text can be saved anywhere, from a notebook, a calendar, to a contact list. Limitations depend only on imagination.

There are some of them with removable batteries, Fairphone is first thing that pops in my mind, it's open source, and they are even giving away free additional battery with every purchase of Fairphone 4 and Fairphone 5 models.
I heard about other alternatives but I don't know how active they are, and there are still cheap dumb phones available in most places.

Another phone that is popular with minimalist people who don't like smartphones is CAT S22:

https://www.talkimg.com/images/2024/05/09/rlJXw.jpeg

I am not a fan of any digital ways of storing seed phrases and private keys, but if for some reason it has to be done, it's good to know there are some options. I would prioritize a device capable of encrypting the data in its memory and, obviously, there can't be any internet, Bluetooth or other ways to transform data from it. Being open-source isn't that important of a factor if there is no way to connect to the internet with it. And even if it is open-source, I doubt security experts were or will be standing in line in the future to investigate the code of 20 year old Casino calculator or a similar gadget.

None of the options on this thread include ENCRYPTION.

Only password protection.... shoddy at best for keeping something as valuable as cryptocurrency private keys secured.

Physical > Encryption > Plain text private keys

YOU NEED LAYERS OF PROTECTION ON THE PHSYICAL DEVICE TO PREVENT A BRUTE FORCE ATTACK.

Using networked devices for this task is a bad idea. Use offline methods.

In the code of a 20-year-old calculator (when the founder didn’t even have thoughts about creating bitcoin) without the ability to connect to the Internet, malicious programs could certainly be hidden. :)
/sarcasm off


What kind of encryption can there be on devices that are not designed to store seed phrases? Let's start with this.

In the devices discussed in this topic, another method of protection is discussed - to hide the seed phrase on a device where no one expects it (masking).

Thank you for your invaluable comments on a thread where no one reads the introduction. ;)

I found another alternative for G-Shock G-2900 watch.
This is another model from Casio and it has the same features and memory with slightly different design and dimensions.
It is using different module 2957 and watch model is G-Shock G-7600

https://www.talkimg.com/images/2024/05/22/1WtJf.jpeg

Here is short video and comparison with G-2900:
https://youtu.be/ifDyyceFDlk

So does your regular writing of seed words on paper, there is no encryption there and no password.  :P
Nobody should used this devices for long term storage of bitcoin llfe savings.

No they don't.
This are not devices designed to protect against brute force attacks, same as paper backup.
You can use Satochip cards for that because they are encrypted.

Most devices mentioned here are dumb and offline dude.

How about making a tails OS USB, encrypt it and store your seed phrases in that USB. In most cases, if anyone get hold of that usb he will format it, because when the tails OS enabled usb is attached to the Windows OS computer, it will shows someting like wrongly formatted ad the person who get that USB will format it to use it. ( there are very few who know about tails OS and even fewer who can think the usd contains seed phrases.

Another thing can be to have your extended seed phrase, where the last four words of the seed phrase to remain in your memory so even if someone hacks into the USB, he or she will still not be able to open your wallet.

Here is the details on How to Install Tails OS on USB flash drive for Wallet Purpose (https://bitcointalk.org/index.php?topic=5228801.msg53920999#msg53920999), you can install the air gapped wallet directly too on the USB.

Have you checked to see what kind of flash memory all these devices are using for their operation?

If it is a NAND flash then you have a security problem there, as the device can be disassembled and the memory extracted in order to try to use more advanced (magnetic?) methods to recover the mnemonic from the memory - even after it is wiped.

If it is of the volatile kind then you need to somehow ensure that the data really is zeroed out by losing electricity after a power off.

Trusting your memory for important data like seed phrases shouldn't be done. You should have physical backups of the entire phrase, not just a bigger or smaller part of it. I know this discussion is about digital backups, but I am just saying. And even if someone found your seed backup that contains 8 out of 12 words, the remaining ones can be bruteforced.