OpenDime or Hardware Wallet?

[Abiky]

There's this thing called the "OpenDime" which claims to be some sort of "Bitcoin Credit Stick". You can carry it around anywhere, pass it along to your friends, without compromising the integrity of the funds contained herein. You'd know that an "OpenDime" wallet's funds have been redeemed if its tamper-evident seal (in this case by unsealing the device with a Push Pin) is broken. They also have a Litecoin version at an affordable price than a regular hardware wallet like the Trezor or the Ledger Nano S.

I'd like to know which is better to use (OpenDime or hardware wallet) for day-to-day transactions? I've been using a hardware wallet for a long time now, but the "OpenDime" seems to be quite an attractive option for storing Bitcoin safely without breaking the bank. Of course, hardware wallets like the CoolWallet S or the Ledger Nano S provide a wide-variety of cryptocurrencies to choose from (unlike the "OpenDime" which is purposed for one coin at a time). But if it proves to be a great alternative to hardware wallets, I'd think most crypto users would go this route since it's the cheapest option to store (and spend) crypto anytime, anywhere.

What are your thoughts? Is this worth it? Or am I better off using a hardware wallet?

[1714544831]

1714544831

[TravelMug]

For the record here is OpenDime Ann thread, [ANN] OPENDIME v3 – Now *Genuine Verified* Bitcoin Credit Stick (in stock!).

Personally, I haven't used OpenDime, so I still prefer Electrum or my local exchanges (coins.ph) for day-to-day transactions, I won't use my hardware wallet for that purpose though.

Of course, there's always this sort of  malfunction" at the back of our mind, and as an electronic devices, there is the question of its life expectancy..

What is the expected lifetime of the device?

Like most electronic devices, if stored properly it should last decades.

The expected reliability of the part that stores the private key as described on the ATSAMD21E17 datasheet is between 25-100 years [page 1014]

For long term HODL/Storage and large amounts we recommend COLDCARD Hardware Wallet a ultra-secure Bitcoin wallet also made by us.

https://opendime.com/faq

So that's 25 to 100 years, assuming you do really protect the device and prevent it from accidental loss. i.e. plugging it to a bad USB port.


Here is a guy who have been carrying OpenDime for over a year:

Source: https://twitter.com/piramida/status/1226068815533891584

[joniboini]

It depends on what you need. If you don't need hand-to-hand or offline transactions I guess hardware wallet like Ledger Nano S is fine.

https://opendime.com/faq give a good explanation of what's the product is useful for.

[hatshepsut93]

OpenDime is not a wallet, so it's a bit wrong to compare it with a hardware wallet, since they are created to solve different tasks. Opendime is more close to a paper wallet, you can store Bitcoin on it, but you can't make transactions with it, you'd need to connect it to a computer and sweep the private key. Basically, Opendime is a sophisticated USB stick. There's no reason to get Opendime if you don't plan to use its main feature - transacting Bitcoin physically by giving someone your Opendime.

Hardware wallet allows you to securely store and transact Bitcoin, which is very useful for newbies who want a quick and simple solution to managing their coins.

[xvids]

OpenDime is not a wallet, so it's a bit wrong to compare it with a hardware wallet, since they are created to solve different tasks. Opendime is more close to a paper wallet, you can store Bitcoin on it, but you can't make transactions with it, you'd need to connect it to a computer and sweep the private key. Basically, Opendime is a sophisticated USB stick. There's no reason to get Opendime if you don't plan to use its main feature - transacting Bitcoin physically by giving someone your Opendime.

Hardware wallet allows you to securely store and transact Bitcoin, which is very useful for newbies who want a quick and simple solution to managing their coins.

I agree this is like comparing Bitcoin to Gold or other things.
Both have different use and each of them stands out in their own features.
For OP I don't think you really need an Opendime you could easily use your hardware wallet for your transactions.

[squatter]

I'd like to know which is better to use (OpenDime or hardware wallet) for day-to-day transactions? I've been using a hardware wallet for a long time now, but the "OpenDime" seems to be quite an attractive option for storing Bitcoin safely without breaking the bank.

OpenDimes and similar devices are most useful as bearer instruments -- literally passed around as cash, without transacting on the blockchain at all. If you want to transact over the blockchain, you need to break the device to sweep the private key.

So, hardware wallets serve a very different purpose. Apples and oranges.

I would also caution against using OpenDimes for large amounts or long term storage, since their design makes it impossible to securely back up the private key.

[o_e_l_e_o]

I'd think most crypto users would go this route since it's the cheapest option to store (and spend) crypto anytime, anywhere.

It is not the cheapest option to spend, though. Although you can send bitcoin to your Opendime as much as you want (because it will show you the public address when you plug it in to a computer), if you want to spend the bitcoin on it you have to break it to reveal the private key. Once you've done that, what you've essentially got is no more secure than just storing a private key on a normal USB stick i.e. not secure at all. Given that each one costs $15, you are paying $15 per transaction, and any change from your transaction would need to be sent to a new Opendime.

The physical security of the device is also massively inferior to that of a hardware wallet. A simple pin push is all that is needed to expose the private key. Anyone who steals your Opendime will be able to access the coins inside within a matter of seconds.

And as squatter says, it is impossible to back up without first breaking it to view the private key, in which case you have defeat its very purpose.

Opendimes serve a particular niche - transacting bitcoin in person without broadcasting a transaction. They are absolutely not a hardware wallet and should not be used as such.

[bitmover]

Opendimes serve a particular niche - transacting bitcoin in person without broadcasting a transaction. They are absolutely not a hardware wallet and should not be used as such.

Exactly
Opendimes are not much better than a mobile wallet imo.
Using a good mobile wallet you can make a lot of transactions very fast. You can use QR codes.. don't need to be carrying an extra device (like open dime) ... as neither of them are as safe as a hardware wallet, they should be used for small amounts of money only.

[Abiky]

For the record here is OpenDime Ann thread, [ANN] OPENDIME v3 – Now *Genuine Verified* Bitcoin Credit Stick (in stock!).

Personally, I haven't used OpenDime, so I still prefer Electrum or my local exchanges (coins.ph) for day-to-day transactions, I won't use my hardware wallet for that purpose though.

Of course, there's always this sort of  malfunction" at the back of our mind, and as an electronic devices, there is the question of its life expectancy..

...

So that's 25 to 100 years, assuming you do really protect the device and prevent it from accidental loss. i.e. plugging it to a bad USB port.

Wow. Never thought that OpenDime would be capable of lasting a very long time. 100 years is more than enough to preserve your crypto balance for future generations to enjoy. While it's not as comparable as a hardware wallet, it makes a great little tool for sending Bitcoin to anyone just as you would with physical cash. And for the price, I'd say that it's worth every penny. The only downside is that the OpenDime works with one cryptocurrency at a time. If the company ever decides to create a new version of the OpenDime that would serve as a "multi-currency" bearer bond stick, it would be a blast. Yet, we're only limited to BTC and LTC versions of the OpenDime stick.

For large amounts of money (crypto), it's best to go for a hardware wallet like Trezor or Ledger Nano S to protect your investment for the long term. The OpenDime would only serve for quick transfers of crypto in small increments. Putting your entire life savings on it, would not be the wisest thing to do.

OpenDimes and similar devices are most useful as bearer instruments -- literally passed around as cash, without transacting on the blockchain at all. If you want to transact over the blockchain, you need to break the device to sweep the private key.

So, hardware wallets serve a very different purpose. Apples and oranges.

I would also caution against using OpenDimes for large amounts or long term storage, since their design makes it impossible to securely back up the private key.

Yes. I've figured that it's impossible to back up the private key for safekeeping. Sensitive information is not released from the device unless you "break it". And doing this will expose your private key to the public. The OpenDime is very similar to a paper wallet in this regard, as once you "break the seal" you cannot reuse the device for your own benefit. But it's a great option for those looking for a safe and secure way of transferring (or even storing) Bitcoin or Litecoin offline.

I've decided to have both a hardware wallet and an OpenDime for safekeeping. For storing large amounts of crypto, a hardware wallet will suffice. But I could use an OpenDime to send money to my friends just as I would with ordinary cash. It's looks more suitable as a sort of "Bitcoin gift card" than anything else. For $15, I'd say that it's quite an affordable little device for sending Bitcoin anytime, anywhere in a completely offline manner.

[igor72]

For hand-to-hand transactions I would prefer Tangem card. It's cheaper and reusable.

[o_e_l_e_o]

For hand-to-hand transactions I would prefer Tangem card. It's cheaper and reusable.

I'd never heard of these before, but they look great. Are they fairly new? Really sleek design. A nice, straightforward way to make off chain transactions and to gift bitcoin to friends who don't have their own wallet yet. An open source app and a good security audit. I might pick up a few of these.

Do you own any? How does it deal with change addresses? From the website it sounds like each card only stores a single private key. Does it just return unspent coins to the same address?

[igor72]

Do you own any? How does it deal with change addresses? From the website it sounds like each card only stores a single private key. Does it just return unspent coins to the same address?

No, I don't own Tangem card. I think you're right, the change returns to the same address. But I can't say for sure.

[squatter]

Do you own any? How does it deal with change addresses? From the website it sounds like each card only stores a single private key. Does it just return unspent coins to the same address?

No, I don't own Tangem card. I think you're right, the change returns to the same address. But I can't say for sure.

It must. From the FAQ, each card indeed only holds a single private key:

Each Tangem Card is fixed to a certain cryptocurrency and can hold one private key at a time.

I'm not a fan of the privacy implications of address reuse, but the idea of a bearer instrument that you can also spend from is pretty exciting. At $13, they are cheaper than OpenDimes (by a hair) but offer a much slicker look and better functionality.

Does anyone know about the company behind them? The site has only been up for a few months.

[Pmalek]

Does anyone know about the company behind them? The site has only been up for a few months.

There isn't much info about them.
The company is called Tangem AG. Their headquarters are in Switzerland.

You can find the addres on the official website, https://tangemcards.com/:
Global Headquarters, Tangem AG,
Baarerstrasse 10, 6300 Zug, Switzerland

It shows up on Google Maps as well.

You can find some more info about the company here:
https://www.uid.admin.ch/Detail.aspx?uid_id=CHE-390.112.525

[Abiky]

For hand-to-hand transactions I would prefer Tangem card. It's cheaper and reusable.

Nice. This looks like a better alternative to the OpenDime because of its sleek design and cheaper price. Sometimes I wonder how could this be reusable without compromising the security of the Bitcoin contained inside the card? If it's as they claim it to be, it'll be a blast to use for day-to-day Bitcoin transactions in a truly P2P manner. At least, the Tangem card has other cryptocurency options like ETH and XLM. As far as I know, the OpenDime is only available for BTC and LTC which greatly limits one's options for paying crypto using it as a bearer instrument.

Considering that the OpenDime or the Tangem card are not suitable for storing large amounts of Bitcoin on it, a hardware wallet is still the best thing around when you want to combine the convenience of hot wallets with the security of a cold wallet. The only downside is that hardware wallets like the Ledger and Trezor are somewhat expensive to acquire.

Nonetheless, bearer instruments like the OpenDime and the Tangem Card are best thing there is when it comes to making quick payments in-person "off-the-grid". But I'd highly recommend a hardware wallet anytime as they have greater advantages than the previously mentioned devices. Just my opinion

[DireWolfM14]

The Tangem card seems legit, but to be honest, I'm not seeing the allure.  I don't necessarily see it as alternative to the Open Dime, other than off-chain hand off.  It seems like it's marketed more as "mobile hardware wallet" that can also be used for off-chain transactions.  So, if you buy one for the NFC to phone function, you should ask yourself; are your funds any more secure than a hot wallet in a mobile app?  I don't think so, quite the contrary, in fact.  They specify in their faqs that unlike a hardware or mobile wallet, if the card is lost, so are the funds.  And therefor, you shouldn't keep a lot of bitcoin on the card.  Well, I don't leave a lot of cash in physical wallet, and I don't keep much bitcoin in my hot wallet.

But, if I lose my phone or it gets stolen, I can brick it as soon as I can find another phone to use.  I have a very strong PIN set on my mobile wallet, and it's different from the strong PIN set to get into my phone.  If I'm able to brick the phone in time, and I don't lose the funds in my hot wallet I'll be able to recover them.  No BTC lost, just the phone itself.

With the Tengem card you need to have your phone available, and you need to have the card available.  If you lose your phone then your card is useless, and if you lose your card your bitcoin is gone.  If you're like me, you probably also lost your cash, because your card was in your leather wallet and you lost the whole god damn thing.  So, you're left with no funds, and phone that can't send bitcoin.  In other words if you lose one or the other, you're fucked.  However, if I lose my wallet I still have my bitcoin I can spend.  If I lose my phone, I probably still have cash or credit cards in my pocket. As long as I don't lose both, I'm not fucked.

[o_e_l_e_o]

The only downside is that hardware wallets like the Ledger and Trezor are somewhat expensive to acquire.

I wouldn't say so. If you are willing to pay $15 for an OpenDime which you can use once, then paying $40-$60 for a Ledger Nano S (depending on what deals they have on at the time) which you can use as many times as you want for years on years hardly seems expensive to me.

So, if you buy one for the NFC to phone function, you should ask yourself; are your funds any more secure than a hot wallet in a mobile app?

Absolutely not. Whoever has possession of the card has possession of the funds. There is no way to back up a seed phrase or private key, and there is no way to apply a password or PIN. It is definitely less secure than a password protected mobile wallet. It is essentially the same as carrying cash. I don't carry much cash around with me either, but I still think it would be cool to be able to be able to physically hand someone $20 worth of BTC, for example, rather than make an on-chain transaction.

[DireWolfM14]

there is no way to apply a password or PIN.

To be fair, it looks like you can enable a pin:

**What if somebody scans my Card and transfers the funds from it?**

Not to worry - nobody will be able to transfer funds from your Card just by scanning it. Although checking the funds takes seconds, transferring them requires you to hold the Card against your phone for 15-30 seconds.

This is a security measure, its duration is configurable and it can be overridden by enabling a PIN-code on the Card (available on demand).

emphasis mine

It looks like you have to order the card with that option enabled, they say they say it's available on demand.  That seems like feature that should come as a default setting, and would be enabled or disabled using the app.

Otherwise, it takes holding the card against your phone for about 30 seconds or so.  It seems like someone could walk around in a crowd with the Tangem app running and scan people's pockets or purses for cards.  Once one is found, he could linger close enough to the card to extract the funds.

[o_e_l_e_o]

To be fair, it looks like you can enable a pin

Ahh good catch. I must have skimmed over that bit.

It seems like someone could walk around in a crowd with the Tangem app running and scan people's pockets or purses for cards.  Once one is found, he could linger close enough to the card to extract the funds.

That would be difficult I think. It says on the website it uses near field communication, which generally has a transmission distance of around 2-3 inches. That's not the same as radio frequency identification which is used to skim credit cards, which can have a range of a couple of feet. Once you factor transmission through a closed wallet and clothing, an attacker would probably have to hold their phone up against the person in question for 30 seconds or so, which seems unlikely to go unnoticed. Still, if you were really concerned about that, then I suppose you could buy an RFID blocking wallet.

[DaveF]

I use OpenDimes and I would not consider them a hardware wallet. More of a digital paper wallet.
Same with the Tangem cards.

Both are nice products for storing BTC and giving to people but there are not wallets.

But in the end are no different then a paper wallet with a sticker over the private key.
Once it's opened, it's out there in the open.

-Dave