E-devices suitable for backup storage of seed phrases.

[m2017]

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

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).

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

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

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

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

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.

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.

[dkbit98]

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.

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:

[Pmalek]

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.

[Eclipse33]

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.

[m2017]

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.

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

None of the options on this thread include ENCRYPTION.

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

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

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.

[dkbit98]

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



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

None of the options on this thread include ENCRYPTION.

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

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

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.

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

Most devices mentioned here are dumb and offline dude.

[UmerIdrees]

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.

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, you can install the air gapped wallet directly too on the USB.

[NotATether]

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.

[Pmalek]

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.

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.