Cold Storage Coins
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.
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
28th December 2017
Application build
The device gets delivered with private keys as defined by the provider!
See test resultPassed 5 of 12 tests
We answered the following questions in this order:
We stopped asking questions after we encountered a failed answer.
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 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”.
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!
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.
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.
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.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.
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.
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.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.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
- obtain the binary from the provider
- compile the published source code using the published build instructions into a binary
- compare the two binaries
- 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
Comes with a partner-tracker app 
Blockchain Mint
Analysis
Singapore based Rearden Metals Pte Ltd touts what it calls its Blockchain Mint service along with its Cold Storage Coins. It is uncanny in its resemblance to the original:
The Casascius coins series was discontinued on the 27th of November, 2013 due to regulatory concerns. The earliest date we could find for Cold Storage Coins was on December 28, 2017. This date is significant because 2017 marked a year for one of Bitcoin’s most notable price increase to $20,000. At the time, $20,000 was the all-time high. 2017 was also the year of the Initial Coin Offering (ICO) when a lot of mainstream investors delved into fundraising projects related to cryptocurrencies.
Cold Storage Coins comes in Bitcoin (BTC), Ethereum, Dogecoin and others. Rearden Metals also offers a customized service for other cryptocurrencies. The Singaporean website Opengovsg.com lists Rearden Metals Pte Ltd’s incorporation date on December 27, 2017
Product Description
Rearden Metals’ Cold Storage Coins come with the following features:
- unique Bitcoin wallet ID
- laser-etched private key QR code
- tamper-resistant holographic film
- fire and flood resistant
- available in 1 oz (28.35 g) 999 Fine Copper or 1 oz 999 Fine Silver
Cold Storage Coins come with a companion app.
How to transfer cryptocurrencies to Cold Storage Coins
- Scan the public key found on the back.
- Enter any amount of cryptocurrency – big or small.
- Authorize the transfer to complete.
- You can use any hot wallet with a ‘paper to wallet sweep’ function to scan the key or download the Cold Storage Coins app.
How to transfer cryptocurrencies to another wallet
- Peel off the tamper-resistant film at the back.
- Use ordinary household solvents like WD-40 to remove excess security adhesive.
- Scan the private QR code to transfer crypto to your desired hot wallet.
Analysis
Similar to 
Casascius Coins , Cold Storage Coins etches the private keys on the coins and thus allows them to make copies of it. The users would have to trust that they won’t.
They did offer a Security Statement, but again, users would just have to take their word for it that the Managing Director won’t make copies of the private keys on each coin they sell.
What happens to the private key once the coin is engraved?
Creating secure Cold Storage Coins is a very complex process that involves laser etching of a private key & private key QR code on every coin’s surface. The integrity of this process is paramount to our product’s success, and this production process is strictly overseen by our Managing Director. The keypair is generated on an offline computer, the lasers are run by computers that have never been online. Each computer is wiped clean using USA Department of Defense quality destruction methods. You can learn more about the steps we take to secure the sensitive information in our Security Statment.
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.
<img src="https://walletscrutiny.com/images/social/bearer/coldstoragecoins.png">
