[LIST] Bitcoin Seed Backup Tools

[Dabs]

It is possible to see through some envelopes by holding it up to a light. There is also more advanced technology that can see through darker paper.

Tamper evident bags are really not intended to prevent an observer from looking at the contents inside the bag.

Agreed that envelopes and even thicker ones or darker ones may still be readable, but could you possibly insert another thick paper in there to make the original paper unreadable without opening the envelope? Or even insert small metal foil so no one can shine a light through? Your potential adversary would need advanced technology and I'd wonder if it may be worth it, or they would rather just open it anyway (and then you'll know someone opened it.)

You could have other forms of security to find out if the site has been tampered with or if anyone else has been to that location, depending on specifics. Cameras, or even other low tech solutions (hair stuck to the door, floor patterns of scattered rubble or whatever, dust?)

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[PrimeNumber7]

It is possible to see through some envelopes by holding it up to a light. There is also more advanced technology that can see through darker paper.

Tamper evident bags are really not intended to prevent an observer from looking at the contents inside the bag.

Agreed that envelopes and even thicker ones or darker ones may still be readable, but could you possibly insert another thick paper in there to make the original paper unreadable without opening the envelope? Or even insert small metal foil so no one can shine a light through? Your potential adversary would need advanced technology and I'd wonder if it may be worth it, or they would rather just open it anyway (and then you'll know someone opened it.)

You could have other forms of security to find out if the site has been tampered with or if anyone else has been to that location, depending on specifics. Cameras, or even other low tech solutions (hair stuck to the door, floor patterns of scattered rubble or whatever, dust?)

Sure, there is a lot you can do to try to ensure that you are aware of a compromise when you visit your offsite backup location.

The problem with the above is that it is generally unusual for someone to visit their offsite backup location, and that most people store all information needed to access coin in a single offsite location.

This will only result in negative outcomes. You will generally not know for a long time vis your tamper evident bag, they your backup has been compromised. There is also the potential that you will have multiple offsite locations compromised and you will not realize it. Or you might sacrifice physical security in favor of using a tamper evident bag that results in your private keys being stolen.

[o_e_l_e_o]

As I noted in my above post, you ultimately need to store all information required to access your coin, including any passphrase, and additional keys if using multisig. You can store this information in multiple places if you so choose.

Which is exactly where a tamper-evident set up is useful. I don't want someone to be able to compromise one of my back up locations and for me to have no knowledge of it. Some of my back ups are for cold storage coins I haven't touched in years and don't plan to touch for years. Do I really want a period of 10+ years with an attacker knowing my seed phrase and attempting to brute force my passphrase, find its back up location, or both, and me having absolutely no knowledge that that is what is happening? Of course not. Even in your hypothetical situation of me only checking my back ups very rarely, a period of few months before I discover the breach is far better than not knowing about the breach at all.

[dkbit98]

I'd probably use a small tin can and screw it together, then put some 2 part epoxy on it, then glitter and other creative stuff. You'll have to break it to open it, and it will be obvious.

Just don't make it super-complicated and don't go crazy with epoxy that would make it impossible to open the can
Maybe one more step would add extra complexity but I like the idea of using binary form for seed words, so that most people wouldn't even know what those dots really are.
https://github.com/jakob6102/seedcard

As I noted in my above post, you ultimately need to store all information required to access your coin, including any passphrase, and additional keys if using multisig. You can store this information in multiple places if you so choose.

Well you need to store everything in this world somewhere, and I would not count on my memory and brain to remember anything important.
You are obviously not going to keep all that in one place, passphrase should always be ins separate location, but what if you forgot where you put all those stuff?
Alzheimer's disease and other neurological disorders are getting more common, and our memory is getting worse and more full with age, that is the case with all hard drives  

[Dabs]

I'd probably use a small tin can and screw it together, then put some 2 part epoxy on it, then glitter and other creative stuff. You'll have to break it to open it, and it will be obvious.

Just don't make it super-complicated and don't go crazy with epoxy that would make it impossible to open the can
Maybe one more step would add extra complexity but I like the idea of using binary form for seed words, so that most people wouldn't even know what those dots really are.
https://github.com/jakob6102/seedcard

Eh, yeah, just use the epoxy to seal it and make it tamper evident, not open-proof.

That binary one is a new take. Previously I was thinking of using 4 digit octal, or 3 digit hexadecimal numbers stamped or etched. I end up deciding I prefer to just etch the whole word. Still a work in progress but there are a few videos on youtube showing how to electrical etch / engrave stainless steel.

[PrimeNumber7]

As I noted in my above post, you ultimately need to store all information required to access your coin, including any passphrase, and additional keys if using multisig. You can store this information in multiple places if you so choose.

Which is exactly where a tamper-evident set up is useful. I don't want someone to be able to compromise one of my back up locations and for me to have no knowledge of it. Some of my back ups are for cold storage coins I haven't touched in years and don't plan to touch for years. Do I really want a period of 10+ years with an attacker knowing my seed phrase and attempting to brute force my passphrase, find its back up location, or both, and me having absolutely no knowledge that that is what is happening? Of course not. Even in your hypothetical situation of me only checking my back ups very rarely, a period of few months before I discover the breach is far better than not knowing about the breach at all.

Everyone has a finale budget for security. I think it would be better to invest whatever you would spend on the tamper evident bags on a more secure/better safe, or other equipment that will prevent an adversary from accessing your seed.

If an adversary is able to access one location storing a portion of your seed, they will likely make a serious attempt to access your other locations. I think it is probably reasonable to expect them to do so within half the interval that you would normally access your off site location.

If you insist on having something in place that alerts you of a potential compromise, I would suggest something that alerts you right away. I think a tamper evident bag is really not much more than a false sense of security. Given enough time, an adversary may even be able to replace the bag, making it appear there was no compromise.

[Dabs]

If you insist on having something in place that alerts you of a potential compromise, I would suggest something that alerts you right away. I think a tamper evident bag is really not much more than a false sense of security. Given enough time, an adversary may even be able to replace the bag, making it appear there was no compromise.

Can't disagree with that. You know these doomsday preppers with hidden bunkers have CCTV or cameras... So they know if anyone has been in the area or tried to get in (or actually got in.) You could have something solar powered that pings you all the time and if it either losses power or the door to your little container has been opened you'll know within a minute. (your device would need to have mobile data or internet or something maybe, or at least ability to send some sort of message.)

My ideal location with be some bunker with a relatively long corridor that they must go through and you have something watching that path. You're also making some assumptions that nothing is going to dig in from the sides or from underneath it, but you can probably have sensors for that too.

[DaveF]

As @dkbit98 multisig is probably the best. Setup a 2 of 3 wallet. Have all three seeds in different locations, sealed in different tamper evident ways.
Check on them often. Someone would have to compromise 2 locations, 2 different ways without you noticing before getting to your BTC.
For more fun, add a 4th location with a seed that has nothing to do with anything.

-Dave

[dkbit98]

I would add that probably best and cheapest way is to make your own DIY backup seed phrase, you just need to purchase stainless steel flat washers and screw with nut that all cost just few dollars.
You would also need to 3dprint or buy plastic Jig, and you need to have metal stamping tool with letters and numbers, but result is amazing very durable backup, and people probably won't suspect what you are using this for.
It may take some time to create this but you can customize, and it's cheaper than all  other listed methods.


https://www.econoalchemist.com/post/backup

[Pmalek]

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They survived both tests quite well. I wonder what would have happened if he continued with the heat test for a few more minutes. Some of the flat washers suffered visible damages. #8 and #16, for example. It should be mentioned that both of those flat washers got some of their clarity back after being soaked in salt water.

[Dabs]

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They survived both tests quite well. I wonder what would have happened if he continued with the heat test for a few more minutes. Some of the flat washers suffered visible damages. #8 and #16, for example. It should be mentioned that both of those flat washers got some of their clarity back after being soaked in salt water.

If your backup is exposed to that kind of temperature for much longer in a real life situation, you have other problems that might need more attention. Normally, with stuff like this, they should be stored inside some waterproof bag, bottle, ziplock or something and that whole thing is buried somewhere it is unlikely to be subject to intense heat.

OT: John Wick stores his gold coins in the basement under concrete.

[SFR10]

I would add that probably best and cheapest way is to make your own DIY backup seed phrase, you just need to purchase stainless steel flat washers
~Snipped~
https://i.imgur.com/0c1gQ1a.jpg
https://www.econoalchemist.com/post/backup

You're right, it's indeed the cheapest one but I'm not so sure if it's the best one. I wish he ^{[@econoalchemist]} would've included the temperature at peak ^{[he had a thermometer]} and the exact time when it reached that level ^{[the video appeared to be on x3, so it was probably less than 3 minutes at around "800 - 900°C"]}.

and people probably won't suspect what you are using this for.

But if there was a way to not include the seed numbers, it would've been a lot better.
^{- Sorry for nitpicking [I do know it's needed to not mess up the order].}

I wonder what would have happened if he continued with the heat test for a few more minutes.

For just a few more minutes, I think we would still be able to read the letters but anything beyond 30 minutes ^{[assuming that the temperature rises gradually]} would probably result in those flat washers melting fast ^{[Stainless steel melting points]}.

[DaveF]

OT: John Wick stores his gold coins in the basement under concrete.

Continuing OT, if someone steals then from him, he is going to get them back.

Seriously, was thinking while driving home. Why was using stainless steel even a thought for the engraved plates, instead of, as o_e_l_e_o said and using titanium or other stronger metals.
For the punched ones, I get it.
But you are never really going to get enough heat to melt titanium or have an impact strong enough to really damage it. Just wondering if it is a case of, "that's what it is" or if there was another reason.

-Dave

[n0nce]

Seriously, was thinking while driving home. Why was using stainless steel even a thought for the engraved plates, instead of, as o_e_l_e_o said and using titanium or other stronger metals.

Probably due to cost. Titanium solutions do exist, like: https://cryptotag.io/products/zeus-starter-kit/. It costs 130€.
I am not sure if engraving holds up as well as punching in extreme conditions simply due to 'modifying' the material less, if that makes sense.
Engraving a word is like a very, very shallow stamp of it, so I prefer stamping. Lopp didn't comment on it much, but I found visually, that the stamped letters held up better.

I have to say, engraving looks often quite bad (it's not as easy to hold such a thing steady as when using a pen ) and stamping isn't much better. The letters are always equal, but can come out crooked, too high / low etc.
While you might think it's irrelevant, I think it's very important for seed backups to remain legible after a long time and maybe extreme conditions as well.

So I like the idea of just punching holes, like in binary format or like in the CryptoTag Zeus which uses 'BIP39 numbers' (indexes: https://cryptotag.io/bip39-list/) instead of BIP39 words: https://github.com/bitcoin/bips/blob/master/bip-0039/english.txt

[o_e_l_e_o]

Why was using stainless steel even a thought for the engraved plates, instead of, as o_e_l_e_o said and using titanium or other stronger metals.

It's a trade off between durability and cost. Stainless steel isn't quite as good as titanium, but it is more than enough for almost everything we care about and it is significantly cheaper. All common alloys of stainless steel have melting points >1400 Celsius, while titanium is around 1650 Celsius. Building fires are generally in the range of around 800-1100 Celsius, so both will hold up fine. Titanium is only a couple of places below 304 stainless steel on the galvanic scale (the lower it is the less reactive it is), so in terms of corrosion although Titanium is slightly better the difference will again be negligible for our purposes. The difference in yield strength equates to something like 13 tons of pressure per square inch for stainless steel and 16 tons of pressure per square inch for titanium, both which will withstand almost all building collapses or similar.

So yeah, if you can afford titanium then go for it, but you'll also be fine using a thick enough piece of stainless steel.

[Dabs]

I think it's best bang for your buck. 304 stainless is better in this regard. 316 or 316L for saltwater, but if you are concerned about that I would just use 304 and put that in plastic container. Then bury it where it can't get burned. You can throw in some oxygen absorbers or fill the container with dry ice (co2) or argon gas. I would just wrap the whole thing with bubble wrap, then bury it somewhere, then pour concrete over it.

Now if it's in a tall building, that's gonna be a problem.

[PrimeNumber7]

Why was using stainless steel even a thought for the engraved plates, instead of, as o_e_l_e_o said and using titanium or other stronger metals.

It's a trade off between durability and cost. Stainless steel isn't quite as good as titanium, but it is more than enough for almost everything we care about and it is significantly cheaper. All common alloys of stainless steel have melting points >1400 Celsius, while titanium is around 1650 Celsius. Building fires are generally in the range of around 800-1100 Celsius, so both will hold up fine. Titanium is only a couple of places below 304 stainless steel on the galvanic scale (the lower it is the less reactive it is), so in terms of corrosion although Titanium is slightly better the difference will again be negligible for our purposes. The difference in yield strength equates to something like 13 tons of pressure per square inch for stainless steel and 16 tons of pressure per square inch for titanium, both which will withstand almost all building collapses or similar.

So yeah, if you can afford titanium then go for it, but you'll also be fine using a thick enough piece of stainless steel.

I think you are making a strong argument against titanium.

There are very few scenarios in which a titanium seed backup will survive when a stainless steel backup plate will not.

You control the location of where the backup plate will be stored, so you can simply keep your backup in a location in which for all intents and purposes, the backup is not going to be subject to conditions that would cause the plates to be unreadable. Sure, there might be a situation in which you are incarcerated for an extended period, the conditions of the subject location change in a way that results in a fire melting a stainless steel plate that would not melt a titanium plate, but the odds of all of these happening are really effectively zero.

I would also repeat my argument that budgets are finite. If you can "afford" titanium, you should buy stainless steel and use the difference in cost to invest in additional/other security measures.

If you insist on having something in place that alerts you of a potential compromise, I would suggest something that alerts you right away. I think a tamper evident bag is really not much more than a false sense of security. Given enough time, an adversary may even be able to replace the bag, making it appear there was no compromise.

Can't disagree with that. You know these doomsday preppers with hidden bunkers have CCTV or cameras... So they know if anyone has been in the area or tried to get in (or actually got in.) You could have something solar powered that pings you all the time and if it either losses power or the door to your little container has been opened you'll know within a minute. (your device would need to have mobile data or internet or something maybe, or at least ability to send some sort of message.)

I was thinking something along the lines of storing your backup in a safety deposit box that contains a device that detects light that has the ability to alert you if light is detected. The device could have a long battery life and may be attached to the back of the container inside the safety deposit box.

My ideal location with be some bunker with a relatively long corridor that they must go through and you have something watching that path. You're also making some assumptions that nothing is going to dig in from the sides or from underneath it, but you can probably have sensors for that too.

I understand you live in a very different part of the world than where I live. I think it would be interesting to one day visit your country as a private citizen in possession of a modest amount of cash. I also understand you are in a unique position for people in your country and might be able to protect private keys better than most other people in your country because of your unique situation.

[o_e_l_e_o]

I would also repeat my argument that budgets are finite. If you can "afford" titanium, you should buy stainless steel and use the difference in cost to invest in additional/other security measures.

Well, it depends. Perhaps you have enough budget to buy all the security measures you want. Perhaps your back up plan is to stamp your seed phrase on a piece of metal, and then screw that metal (face down) on to the concrete foundations of your house under your floor boards or in your basement, in which case there is nothing else to spend your budget on. Perhaps someone can source some scrap titanium for a very reasonable price, or even have some left over from one of their own projects. But yes, as I said above (and as has been shown by Jameson Lopp's stress tests), stamping or engraving on stainless steel will be more than enough for almost every situation.

When considering the cost of tamper evident bags or seals, these can be bought for less than 5 bucks, which is not enough to make a meaningful difference to the quality of a safe, the grade of metal you are using, a remote alert device, etc.

[Dabs]

I was thinking something along the lines of storing your backup in a safety deposit box that contains a device that detects light that has the ability to alert you if light is detected. The device could have a long battery life and may be attached to the back of the container inside the safety deposit box.

Check out the Haven app, for android. It uses any android phone and it's sensors. Most phones have cameras (for light) and acceler---xxx the GPS thingy and a magneto-compass thingy. Whatever it's called, it can detect light or if the phone is moved.

Problem is battery life. Even if you attach a large power bank, it will eventually die.

Can probably use the cheapest Samsung J6 or something $100 phone, put it in ultra-low-power mode ... safety deposit boxes are usually dark, you can probably place it in some other location that has a window for sunlight and use a solar charger. Charges the phone during the day, runs on battery at night ... if it's within range of cell tower you can have it on the lowest prepaid plan and you'll maybe get an alert if something moves.

I understand you live in a very different part of the world than where I live. I think it would be interesting to one day visit your country as a private citizen in possession of a modest amount of cash. I also understand you are in a unique position for people in your country and might be able to protect private keys better than most other people in your country because of your unique situation.

I've moved quite a bit away from there, it's not a secret where I am, but rather not make it public, OpSec and all that. There are local exchanges and almost like El Salvador some merchants accept bitcoins, (some accept altcoins / shitcoins / erc20 tokens) ... I don't have access to my imaginary bunker, but something I'd like to personally build where ever I end up living.

I do keep a house in that country since it was cheap to buy and maintain. It does not have a basement, but it has a small back yard, so I can bury something there. Actually, it would make more sense to just keep whatever backup seed metal plates inside that house. ... hmmm... 3rd world problems eh..

BTW, don't bring too much cash, just enough, the rest you can bring as bitcoin and exchange that once you are in the country. Actually, you can probably bring in $10k USD cash no issues and then use local money changer or banks to convert to local fiat money. If you're staying longer than 90 days, you may need a visa or something. Otherwise, tourist visa on arrival is good for about that long.

[Husires]

I think this topic deserves a little bump