Bitfylatest release: 3.10.22 ( 16th December 2021 ) last analysed 3rd September 2021 No source for current release found
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Do your own research!
Try out searching for "lost bitcoins", "stole my money" or "scammers" together with the wallet's name, even if you think the wallet is generally trustworthy. For all the bigger wallets you will find accusations. Make sure you understand why they were made and if you are comfortable with the provider's reaction.
The Analysis ¶
(Analysis from Android review)
Bitfy is a Brazilian app that claims to have a:
All-in-one digital wallet ensures that users are the only ones who have access to private keys.
Translated using Google Translate, it explicitly states its self-custodial nature
We are a non-custodant portfolio, we do not have access to your keys.
On the surface, it may seem that the app has many of the characteristics for ‘good’ self-custodial bitcoin wallet. But we proceeded to investigate further by looking at the reviews and downloaded the app.
One of the more indicting reviews on Google Play was this:
Luiz Sahb Druziani
★☆☆☆☆ May 28, 2020
Do not use this wallet. The seed provided by them works only in the bitfy app, that is, if the app disappears, your money goes with it.
To verify this, we proceeded to download the app on a Samsung Phone.
They ask for your email address and mobile phone number. After filling in some personal details, you are asked to verify.
Then you are asked to create an app password and a pin. The pin is used for a variety of things including payments and the provision of the 12 seed words which are then sent via email after creating a wallet. The only way to open the PDF that contains the seed words is through the 6-digit pin.
However, this is potentially poor protection for a wallet backup. They have 100k downloads and send mnemonics from their servers with a 6 digit pin “password protection”. The app claims to be self-custodial but it is possible for them to access the mnemonics.
Even if they delete the mnemonic after sending it to the user (which cannot be proven), now the user’s email provider and a bunch of other servers have a copy, too. 6 digits only protects against manual, not automated brute force.
The seed words are non-standard mnemonics. They are not found in the BIP39 list. Specifically, the Portuguese mnemonics.
Unfortunately as of this writing, we were not able to import a wallet created using Bitfy using Electrum. Perhaps, more tests are warranted.
While keeping all this in mind this app is still classifiable as a non-custodial wallet. However, with no source in sight, we do not have the means to verify this wallet.
Without public source of the reviewed release available, this product cannot be verified!
As part of our Methodology, we ask:Is the source code publicly available? If not, we tag it No Source!
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.
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