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BITHD Watch 2

Latest Release: v4.2.0 7th December 2022

Our wallet review process

We examine wallets starting at the code level and continue all the way up to the finished app that lives on your device. Provided below is an outline of each of these steps along with security tips for you and general test results.

Developer

Website

Custody

Private keys generated and held by user

But This product went out of business ... or so. Read the analysis for details.

As part of our Methodology, we ask: Is the provider ignorant of the keys?

The answer is "yes". Private keys are generated by the user on the wallet.
Read more

Source code

Public on github

Released

18th January 2019

Application build

We could not verify that the provided code matches the binary!

See test result
Tested 6th August 2024

Platform notes

There is no globally accepted definition of a hardware wallet. Some consider a paper with 12 words a hardware wallet - after all paper is a sort of hardware or at least not software and the 12 words are arguably a wallet(‘s backup). For the purpose of this project we adhere to higher standards in the hardware wallet section. We only consider a hardware wallet if dedicated hardware protects the private keys in a way that leaves the user in full and exclusive control of what transactions he signs or not. That means:

  • The device allows to create private keys offline

  • The device never shares private key material apart from an offline backup mechanism

  • The device displays receive addresses for confirmation
  • The device shares signed transactions after informed approval on the device without reliance on insecure external hardware

Passed 11 of 12 tests

We answered the following questions in this order:
We stopped asking questions after we encountered a failed answer.

Is this product the original?

The answer is "yes".
If the answer was "no", we would mark it as "Fake" and the following would apply:

The answer is "no". We marked it as "Fake".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Fake" and the following would apply:

The bigger wallets often get imitated by scammers that abuse the reputation of the product by imitating its name, logo or both.

Imitating a competitor is a huge red flag and we urge you to not put any money into this product!

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Can we expect the product to ever be released?

The answer is "yes".
If the answer was "no", we would mark it as "Announced but never delivered" and the following would apply:

The answer is "no". We marked it as "Announced but never delivered".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Announced but never delivered" and the following would apply:

Some products are promoted with great fund raising, marketing and ICOs, to disappear from one day to the other a week later or they are one-man side projects that get refined for months or even years to still never materialize in an actual product. Regardless, those are projects we consider “vaporware”.

Is this product available yet?

The answer is "yes".
If the answer was "no", we would mark it as "Un-Released" and the following would apply:

The answer is "no". We marked it as "Un-Released".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Un-Released" and the following would apply:

We focus on products that have the biggest impact if things go wrong and while pre-sales sometimes reach many thousands to buy into promises that never materialize, the damage is limited and there would be little definite to be said about an unreleased product anyway.

If you find a product in this category that was released meanwhile, please contact us to do a proper review!

Is it a wallet?

The answer is "yes".
If the answer was "no", we would mark it as "Not a wallet" and the following would apply:

The answer is "no". We marked it as "Not a wallet".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Not a wallet" and the following would apply:

If it’s called “wallet” but is actually only a portfolio tracker, we don’t look any deeper, assuming it is not meant to control funds. What has no funds, can’t lose your coins. It might still leak your financial history!

If you can buy Bitcoins with this app but only into another wallet, it’s not a wallet itself.

Is it for bitcoins?

The answer is "yes".
If the answer was "no", we would mark it as "A wallet but not for Bitcoin" and the following would apply:

The answer is "no". We marked it as "A wallet but not for Bitcoin".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "A wallet but not for Bitcoin" and the following would apply:

At this point we only look into wallets that at least also support BTC.

Is the provider ignorant of the keys?

The answer is "yes".
If the answer was "no", we would mark it as "Provided private keys" and the following would apply:

The answer is "no". We marked it as "Provided private keys".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Provided private keys" and the following would apply:

The best hardware wallet cannot guarantee that the provider deleted the keys if the private keys were put onto the device by them in the first place.

There is no way of knowing if the provider took a copy in the process. If they did, all funds controlled by those devices are potentially also under the control of the provider and could be moved out of the client’s control at any time at the provider’s discretion.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Does the device hide your keys from other devices?

The answer is "yes".
If the answer was "no", we would mark it as "Leaks Keys" and the following would apply:

The answer is "no". We marked it as "Leaks Keys".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Leaks Keys" and the following would apply:

Some people claim their paper wallet is a hardware wallet. Others use RFID chips with the private keys on them. A very crucial drawback of those systems is that in order to send a transaction, the private key has to be brought onto a different system that doesn’t necessarily share all the desired aspects of a hardware wallet.

Paper wallets need to be printed, exposing the keys to the PC and the printer even before sending funds to it.

Simple RFID based devices can’t sign transactions - they share the keys with whoever asked to use them for whatever they please.

There are even products that are perfectly capable of working in an air-gapped fashion but they still expose the keys to connected devices.

This verdict is reserved for key leakage under normal operation and does not apply to devices where a hack is known to be possible with special hardware.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Can the user verify and approve transactions on the device?

The answer is "yes".
If the answer was "no", we would mark it as "Bad Interface" and the following would apply:

The answer is "no". We marked it as "Bad Interface".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Bad Interface" and the following would apply:

These are devices that might generate secure private key material, outside the reach of the provider but that do not have the means to let the user verify transactions on the device itself. This verdict includes screen-less smart cards or USB-dongles.

The wallet lacks either a screen or buttons or both. In consequence, crucial elements of approving transactions is being delegated to other hardware such as a general purpose PC or phone which defeats the purpose of a hardware wallet. For big exit scams, a companion app could always request two signatures - one for the coffee you are paying and a second to empty your wallet completely. The former could be broadcast while the latter only gets collected for later use.

Another consquence of a missing screen is that the user is faced with the dilemma of either not making a backup or having to pass the backup through an insecure device for display or storage.

The software of the device might be perfect but this device cannot be recommended due to this fundamental flaw.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Is the source code publicly available?

The answer is "yes".
If the answer was "no", we would mark it as "No source for current release found" and the following would apply:

The answer is "no". We marked it as "No source for current release found".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "No source for current release found" and the following would apply:

A wallet that claims to not give the provider the means to steal the users’ funds might actually be lying. In the spirit of “Don’t trust - verify!” you don’t want to take the provider at his word, but trust that people hunting for fame and bug bounties could actually find flaws and back-doors in the wallet so the provider doesn’t dare to put these in.

Back-doors and flaws are frequently found in closed source products but some remain hidden for years. And even in open source security software there might be catastrophic flaws undiscovered for years.

An evil wallet provider would certainly prefer not to publish the code, as hiding it makes audits orders of magnitude harder.

For your security, you thus want the code to be available for review.

If the wallet provider doesn’t share up to date code, our analysis stops there as the wallet could steal your funds at any time, and there is no protection except the provider’s word.

“Up to date” strictly means that any instance of the product being updated without the source code being updated counts as closed source. This puts the burden on the provider to always first release the source code before releasing the product’s update. This paragraph is a clarification to our rules following a little poll.

We are not concerned about the license as long as it allows us to perform our analysis. For a security audit, it is not necessary that the provider allows others to use their code for a competing wallet. You should still prefer actual open source licenses as a competing wallet won’t use the code without giving it careful scrutiny.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Is the decompiled binary legible?

The answer is "yes".
If the answer was "no", we would mark it as "Obfuscated" and the following would apply:

The answer is "no". We marked it as "Obfuscated".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Obfuscated" and the following would apply:

When compiling source code to binary, usually a lot of meta information is retained. A variable storing a masterseed would usually still be called masterseed, so an auditor could inspect what happens to the masterseed. Does it get sent to some server? But obfuscation would rename it for example to _t12, making it harder to find what the product is doing with the masterseed.

In benign cases, code symbols are replaced by short strings to make the binary smaller but for the sake of transparency this should not be done for non-reproducible Bitcoin wallets. (Reproducible wallets could obfuscate the binary for size improvements as the reproducibility would assure the link between code and binary.)

Especially in the public source cases, obfuscation is a red flag. If the code is public, why obfuscate it?

As obfuscation is such a red flag when looking for transparency, we do also sometimes inspect the binaries of closed source apps.

As looking for code obfuscation is a more involved task, we do not inspect many apps but if we see other red flags, we might test this to then put the product into this red-flag category.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Can the product be built from the source provided?

The answer is "yes".
If the answer was "no", we would mark it as "Failed to build from source provided!" and the following would apply:

The answer is "no". We marked it as "Failed to build from source provided!".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Failed to build from source provided!" and the following would apply:

Published code doesn’t help much if the app fails to compile.

We try to compile the published source code using the published build instructions into a binary. If that fails, we might try to work around issues but if we consistently fail to build the app, we give it this verdict and open an issue in the issue tracker of the provider to hopefully verify their app later.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Does the published binary match the published source code?

The answer is "yes".
If the answer was "no", we would mark it as "Not reproducible from source provided" and the following would apply:

The answer is "no". We marked it as "Not reproducible from source provided".

We did not ask this question because we failed at a previous question.
If the answer was "no", we would mark it as "Not reproducible from source provided" and the following would apply:

Published code doesn’t help much if it is not what the published binary was built from. That is why we try to reproduce the binary. We

  1. obtain the binary from the provider
  2. compile the published source code using the published build instructions into a binary
  3. compare the two binaries
  4. we might spend some time working around issues that are easy to work around

If this fails, we might search if other revisions match or if we can deduct the source of the mismatch but generally consider it on the provider to provide the correct source code and build instructions to reproduce the build, so we usually open a ticket in their code repository.

In any case, the result is a discrepancy between the binary we can create and the binary we can find for download and any discrepancy might leak your backup to the server on purpose or by accident.

As we cannot verify that the source provided is the source the binary was compiled from, this category is only slightly better than closed source but for now we have hope projects come around and fix verifiability issues.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.

Application build test result

Update 2024-08-20

The last firmware release is dated December 7, 2022. The page for the device now results in a 403 - Forbidden error. This indicates that this item is no longer for sale. This is reflected in their announcement made in 2023. With a product no longer on sale and the last update to the firmware in 2022, we can say that this is already defunct

Previous Review 2021-12-21

There is currently several red flags about this product.

  • Companion app with terrible rating and accusations
  • No social media links
  • Out of stock product with no word on plans to re-stock

For the latest firmware version, we try the same as last time, wrapped into this script:

$ ./scripts/test/hardware/bithdwatches.sh 4.1.8
...
Filename    : build/bithd-v4.1.8-unsigned.bin
Fingerprint : 7c3126aaff2e983c89f621fa7a3d269385832aeeccc3f13ddd1e540656b059d2
Size        : 417820 bytes (out of 491520 maximum)
Warning: Your Pipfile requires python_version 3.8, but you are using 3.9.2 (/home/leo/.local/share/v/b/bin/python).
  $ pipenv check will surely fail.
Prepare to add metadata ...
Firmware size 418076 bytes
Firmware fingerprint: 7c3126aaff2e983c89f621fa7a3d269385832aeeccc3f13ddd1e540656b059d2
90d795380fa7def90f4924a672b64d086b55892266be8baae12c63871ab6598b  bithd-v4.1.8-signed.bin
1c1
< 00000000: 5452 5a52 1c60 0600 0000 0001 0000 0000  TRZR.`..........
---
> 00000000: 5452 5a52 1c60 0600 0304 0501 0000 0000  TRZR.`..........
5,16c5,16
< 00000040: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 00000050: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 00000060: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 00000070: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 00000080: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 00000090: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 000000a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 000000b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 000000c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 000000d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 000000e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
< 000000f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
---
> 00000040: 2d28 206f 38de d998 bd9d 96d4 b845 35ae  -( o8........E5.
> 00000050: 758c b6ae e8ea 6c32 3028 94d7 4300 d300  u.....l20(..C...
> 00000060: fc0c c4db c3dd 4a54 d2d7 8922 267a 7cb4  ......JT..."&z|.
> 00000070: 8032 f675 79c3 e527 54dc 8e8b 3bd2 8460  .2.uy..'T...;..`
> 00000080: 9444 0f18 3490 e32c dc62 aeb4 8ba9 c903  .D..4..,.b......
> 00000090: 675c 7e43 810d d87e bb72 1ac0 4757 a27f  g\~C...~.r..GW..
> 000000a0: f9a8 b6f2 2d28 0f51 83ff bc81 89de a39d  ....-(.Q........
> 000000b0: 4631 332b dce9 b3d2 38c4 fa80 cde0 3fde  F13+....8.....?.
> 000000c0: 09ae 5bcb 7b6e 53dd b391 61a3 de1b 9a06  ..[.{nS...a.....
> 000000d0: d74e 0c37 5d89 7c42 0051 05e0 cd80 edcc  .N.7].|B.Q......
> 000000e0: 1200 16f8 56bf c8c9 e14d dcc6 fd91 2159  ....V....M....!Y
> 000000f0: 35a2 6832 ca7d a678 11c8 48d2 17f1 2c2b  5.h2.}.x..H...,+
425c425
< 00001a80: 8019 0408 0000 0020 c5bc 0020 9219 0408  ....... ... ....
---
> 00001a80: 9519 0408 0000 0020 c5bc 0020 8019 0408  ....... ... ....
12713,12715c12713,12715
< 00031a80: 6269 7463 6f69 6e74 7265 7a6f 722e 636f  bitcointrezor.co
< 00031a90: 6d00 37cb c888 2133 3c8d 0c63 42b1 7fba  m.7...!3<..cB...
< 00031aa0: 9e8d 84b3 757a 0050 696e 206d 6973 6d61  ....uz.Pin misma
---
> 00031a80: f5f3 8317 45a6 190b 00fb 0262 b9c7 09af  ....E......b....
> 00031a90: 7618 49f8 0062 6974 636f 696e 7472 657a  v.I..bitcointrez
> 00031aa0: 6f72 2e63 6f6d 0050 696e 206d 6973 6d61  or.com.Pin misma

This is a bigger diff than we expected. The first two chunks are ok as these are

  • a 3-byte diff in the very beginning, which might be due to different file structure as per chunk #4 but probably nothing malicious.
  • a signature-sized chunk where the compiled version holds zeros. This is expected.

Later chunks though are harder to interpret.

  • Chunk #3 it is again a 2 byte change, where one byte might have moved, indicating some sorting inconsistency … maybe
  • The last chunk again has some sequences moved but it gets hard to interpret as it’s slightly bigger.

In summary, this makes the firmware not verifiable although it all looks pretty harmless as in “too small to actually be malicious”.

Now we would love to get in touch with the provider but their issue tracker is not open. Given their repository has not seen any update in months, together with the lack of social accounts, this product feels pretty unmaintained.

Tests performed by Matthew Lamb, Daniel Andrei R. Garcia, Leo Wandersleb

Previous application build tests

11th December 2021 4.1.7  

Do your own research

In addition to reading our analysis, it is important to do your own checks. Before transferring any bitcoin to your wallet, look up reviews for the wallet you want to use. They should be easy to find. If they aren't, that itself is a reason to be extra careful.