This product still needs to be evaluated some more. We only gathered name, logo and maybe some more details but we have not yet come to a conclusion what to make of this product.

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

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”.

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!

We focus on products that have the biggest impact if things go wrong and this one probably doesn’t have many users according to data publicly available.

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.

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

If it is for holding BTC but you can’t actually send or receive them with this product then it doesn’t function like a wallet for BTC but you might still be using it to hold your bitcoins with the intention to convert back to fiat when you “cash out”.

All products in this category are custodial and thus funds are at the mercy of the provider.

A custodial service is a service where the funds are held by a third party like the provider. The custodial service can at any point steal all the funds of all the users at their discretion. Our investigations stop there.

Some services might claim their setup is super secure, that they don’t actually have access to the funds, or that the access is shared between multiple parties. For our evaluation of it being a wallet, these details are irrelevant. They might be a trustworthy Bitcoin bank and they might be a better fit for certain users than being your own bank but our investigation still stops there as we are only interested in wallets.

Products that claim to be non-custodial but feature custodial accounts without very clearly marking those as custodial are also considered “custodial” as a whole to avoid misguiding users that follow our assessment.

This verdict means that the provider might or might not publish source code and maybe it is even possible to reproduce the build from the source code but as it is custodial, the provider already has control over the funds, so it is not a wallet where you would be in exclusive control of your funds.

We have to acknowledge that a huge majority of Bitcoiners are currently using custodial Bitcoin banks. If you do, please:

• Do your own research if the provider is trust-worthy!
• Check if you know at least enough about them so you can sue them when you have to!
• Check if the provider is under a jurisdiction that will allow them to release your funds when you need them?
• Check if the provider is taking security measures proportional to the amount of funds secured? If they have a million users and don’t use cold storage, that hot wallet is a million times more valuable for hackers to attack. A million times more effort will be taken by hackers to infiltrate their security systems.

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.

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.

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.

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.

If we can reproduce the binary we downloaded from the public source code, with all bytes accounted for, we call the product reproducible. This does not mean we audited the code but it’s the precondition to make sure the public code has relevance for the provided binary.

If the provider puts your funds at risk on purpose or by accident, security researchers can see this if they care to look. It also means that inside the company, engineers can verify that the release manager is releasing the product based on code known to all engineers on the team. A scammer would have to work under the potential eyes of security researchers. He would have to take more effort in hiding any exploit.

“Reproducible” does not mean “verified”. There is good reason to believe that security researchers as of today would not detect very blatant backdoors in the public source code before it gets exploited, much less if the attacker takes moderate efforts to hide it. This is especially true for less popular projects.

If the product is run from the source code using an interpreted language or the user is required to compile the binary himself, transparency is given in that the provided source code is what runs on the product.

This does not mean we audited the code but any reviews of the public code are immediately relevant for the security of the product.

If the provider puts your funds at risk on purpose or by accident, security researchers can see this if they care to look. A scammer would have to work under the potential eyes of security researchers. He would have to take more effort in hiding any exploit.

There is good reason to believe that security researchers as of today would not detect very blatant backdoors in the public source code before it gets exploited, much less if the attacker takes moderate efforts to hide it. This is especially true for less popular projects.

We feature this verdict above the “reproducible” verdict as it completely side-steps the issue of binary transparency. There can be no reproducibility issues with the next release. On the other hand, using these products might be more involved as compiling is required and interpreted languages like Java Script might be inherently less secure than other languages.

Discontinued products or worse, products of providers that are not active anymore, are problematic, especially if they were not formerly reproducible and well audited to be self-custodial following open standards. If the provider hasn’t answered inquiries for a year but their server is still running or similar circumstances might get this verdict, too.

Bitcoin wallets are complex products and Bitcoin is a new, advancing technolgy. Projects that don’t get updated in a long time are probably not well maintained. It is questionable if the provider even has staff at hands that is familiar with the product, should issues arise.

This verdict may not get applied if the provider is active and expresses good reasons for not updating the product.

Bitcoin wallets are complex products and Bitcoin is a new, advancing technolgy. Projects that don’t get updated in a year are probably not well maintained.

This verdict may not get applied if the provider is active and expresses good reasons for not updating the product.

Verdicts apply to very specific releases of products and never to the product as a whole. A new release of a product can change the product completely and thus also the verdict. This product remains listed according to its latest verdict but readers are advised to do their own research as this product might have changed for the better or worse.

This meta verdict is applied in cases of reviews that we identify as requiring an update.

This meta verdict applies to all products with verdict “reproducible” as soon as a new version is released until we test that new version, too. It also applies in cases where issues we opened are marked as resolved by the provider.

If we had more resources, we would update reviews more timely instead of assigning this meta verdict ;)

Many hardware wallet projects aim to be as transparent as possible by using only off-the-shelf hardware with an open design and open code. If the product reviewed is not available in an assembled form - if the user has to source his own hardware to then maybe solder and compile software to install on the device it falls into this category.

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.

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.

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 an output device such as a screen, an input device such as touch or physical 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.

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.

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.

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.