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Ballet Crypto Bitcoin Block

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

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Custody

Provided Keys!

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

The answer is "no". Therefore we marked it as "Provided private keys".
Read more

Source code

Released

We could not determine when this product was originally released.

Application build

The device gets delivered with private keys as defined by the provider!

See test result
Tested 18th May 2022

Platform notes

Bearer tokens are meant to be passed on from one user to another similar to cash or a banking check. Unlike hardware wallets, this comes with an enormous “supply chain” risk if the token gets handed from user to user anonymously - all bearer past and present have plausible deniability if the funds move. We used to categorize bearer tokens as hardware wallets, but decided that they deserved an altogether different category. Generally, bearer tokens have these attributes:

  • Secure initial setup
  • Tamper evidence
  • Balance check without revealing private keys
  • Small size
  • Low unit price

and either of these applies:

  • Somebody has a backup and needs to be trusted
  • Nobody has a backup and funds are destroyed if the token is lost or damaged

Passed 5 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 at all time?

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

The answer is "no". We marked it as "Plain Keys when spending".

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

These devices keep the user’s private key sealed until the seal is broken or removed.

In order for a transfer to commence, the private keys have to be brought onto a different system that might not be secure.

There are many viruses known to look for Bitcoin private keys in memory or hard drives.

While this aspect should not leave room for major exit scams, the handling of such devices is delicate and prone to loss of funds to hackers.

To redeem your funds safely, create your transaction on an offline machine and verify the signed transaction on a different machine before broadcasting it.

Can the user verify and approve transactions on the device?

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

The answer is "no". We marked it as "Transactions are signed blindly".

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

Devices in this category are first sealed. Once the seal is broken, they sign transactions that they are presented with but have no built-in screen to verify what’s being signed.

That makes them prone to malicious companion apps that they rely on for sending.

While this leaves little room for major exit scams, the handling of such devices is delicate.

To redeem your funds safely, create your transaction on an offline machine and verify the signed transaction on a different machine before broadcasting it.

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

Background

The Ballet Crypto Bitcoin Block is another product from Ballet Crypto

Product Description

Bitcoin BLOCKs contain the entire coinbase reward of a newly-mined block. This includes both the base block reward of 6.25 BTC as well as all transaction fees mined in that block.

“Virgin Bitcoins”

The bitcoins come straight from our mining pool partner, mined directly from the coinbase transaction in each block, straight to your physical Bitcoin BLOCK, with no intermediate hops. These bitcoins have no prior transaction history, and thus provide the highest level of privacy.

The concept the provider is getting at here is “taint” and goes back to a Case Law ruling in England of 1758 (Miller vs. Race). “Does the recipient have to care about the origin or history of a bank note?” Judges ruled “No!” as otherwise bank notes simply wouldn’t work as money. Bitcoin today has no such ruling in its favor and some actors already seize or reject Bitcoins that by their assumptions are the proceeds of illegal activities. The provider here is offering “virgin” as in “freshly minted” Bitcoins under the assumption that those are without any history attached.

The claim that these coins “provide the highest level of privacy” obviously is false as the provider knows the identity of the buyer. If those coins themselves now are used in a crime, law enforcement would have a name and address to go ask about it. That is the opposite of “privacy”.

Private Keys

Bitcoin BLOCKs are made using Ballet’s innovative Two-Factor Key Generation (2FKG) process, which utilizes the industry standard BIP38 process to split the private key into two components (the BIP38 passphrase and the encrypted private key). Bitcoin BLOCKs are manufactured in two separate steps in two different locations around the world. This provides what we consider to be the highest level of private key security for the customer.

Included in the block are the following:

  1. Block number
  2. Block reward
  3. Serial number
  4. Bitcoin address (QR code)
  5. Bitcoin address (text)
  6. Tamper-evident scratch-off
  7. BIP38 passphrase
  8. Encrypted private key (QR code)
  9. Encrypted private key (text)
  10. Honeycomb pattern indicating tampering

Unlike other Ballet Crypto products, potential buyers would have to contact Ballet if they are interested. This is not available in their online store.

Analysis

Ballet Crypto’s 2FKG process has been tackled before in the reviews noted above. The CEO, Bobby Lee even put up a hacking challenge for 2 BTC.


In the challenge, he displays 2 Ballet Crypto Real cards. One with the encrypted private key in full display and the other with the passphrase displayed. Hackers would try to find the passphrase for the former, and the private key for the other.

The premise is that ‘collusion’ between two parties in the manufacturing process is in the realm of possibility. As to the BIP-38 encrypted passphrase, the $5 wrench attack does have the potential to coerce the owner to give up his passphrase under duress.

This leads us to a similar verdict about the dangers of having the private keys printed on the bearer token.

Tests performed by Daniel Andrei R. Garcia

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.