Flash: Rewards & Payments
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.
Released
8th August 2024
Custody
⚠️ Mixed custody model
As part of our Methodology, we ask: Does the product allow self-custody?
This product has features that involve third-party custody. While you may hold keys for on-chain funds, some functionality depends on trusting external parties. See warnings below.
Read more
Application build
If you have a binary for a version that doesn't appear on the list, you can dropselect the file here to register it so somebody can verify its reproducibility:
Distribution
Passed all 7 tests
We answered the following questions in this order:
The answer is "yes".
If the answer were "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 were "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 were "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 were "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 were "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 were "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 were "no", we would mark it as "Can't send or receive bitcoins" and the following would apply:
The answer is "no". We marked it as "Can't send or receive bitcoins".
We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Can't send or receive bitcoins" and the following would apply:
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.
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 were "no", we would mark it as "Custodial: The provider holds the keys" and the following would apply:
The answer is "no". We marked it as "Custodial: The provider holds the keys".
We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Custodial: The provider holds the keys" and the following would apply:
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.
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.
The answer is "yes".
If the answer were "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 were "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.
Application information
(Analysis from Android review)
App Description from Google Play
Flash is helping bring the digital finance ecosystem to the Caribbean. Flash is built on top of the Bitcoin and Lightning Networks. Based on the code that runs Blink wallet, it uses the infrastructure from Galoy.
Flash has built reliable Bitcoin Lightning Payments for All: Flash is a wallet you can reach for when you need payment speed and reliability. Rest assured knowing that Flash has dedicated global partners managing Lightning Network liquidity and channels, handling support requests, and improving the app every day.
Great Wallet for Beginners: Flash is designed to make your first steps in Bitcoin simple. Flash is an easy to use, reliable and feature-rich custodial Lightning wallet for everyday payments.
Low Fees Across the Board: Whether you’re sending or receiving via the Lightning Network, Flash Wallet ensures fees are kept to a minimum, often lower than other ways to pay. Transfers between Flash users are entirely free—send and receive without the worry of high fees.
USD Stability & Bitcoin Flexibility: Keep your account stable with our Stabilized USD-equivalent accounts, providing a hedge against volatility for your short-term spending. Fully compatible with the Lightning Network, Flash Wallet ensures your funds are as flexible as they are stable.
Receive Bitcoin Your Way: Flash Wallet provides many ways to receive Bitcoin, including custom Lightning Addresses for each user, printable LNURL Paycodes and more. Receive Bitcoin via NFC technology, making transactions as simple as a tap with devices like bolt cards or rings, or redeem bitcoin from QR vouchers such as Azteco and Lightsats effortlessly, thanks to the new LNURL-withdraw feature.
Bitcoin Point of Sale for Merchants: Every Flash wallet user has a receive-only, web-based Point of Sale “Cash Register.” This lets employees or anybody else create invoices on behalf of the business. It can be pinned to an employee’s home screen, or shared on-line for receiving donations or tips.
Experience and Learn Bitcoin in your Native Language: Multiple languages make Flash Wallet feel built for you, regardless of where you live. Today, the wallet is translated to English, Spanish, French, Portuguese, Czech, German, Thai, Catalan, Swahili and many more. The Flash bitcoin wallet is available in more than 20 languages. Don’t see your language? Reach out to us on Twitter at @LNFlash or on Nostr at @npub1l080awn9wsw87ywm3flmpmccf5rmlvhd7vfgspj2pnavxupnlfesmflash to request a new language.
Open Source Bitcoin Wallet: True to the Bitcoin ethos, the Flash bitcoin wallet is built on Free and Open Source Software (FOSS). Flash is built on open source Bitcoin banking infrastructure maintained by IBEX, and open source non-custodial Bitcoin software development kit maintained by Breez technologies.
Key Features for Flash Users:
- Custom Lightning Address for all Flash users (username@flashapp.me)
- NFC capabilities for receiving Bitcoin with convenience.
- Email authentication for enhanced account security.
- Nostr enabled DM and group chat capabilities (coming soon)
- Comprehensive in-app Bitcoin education, ideal for beginners.
Additional Advantages:
- Zero fees for transactions within Flash Wallet users.
- A detailed log for all your Bitcoin payments.
- An intuitive contact list for frequent transactions.
- A map pinpointing local businesses that accept Bitcoin via Lightning.
- Compatibility with leading wallets such as Blink, Strike, Phoenix, CashApp, River, and Wallet of Satoshi & more.
Download Flash Wallet today and join a growing community embracing Bitcoin.
Analysis
Flash Wallet explicitly identifies as hybrid-custodial, stating that it relies on “dedicated global partners managing Lightning Network liquidity and channels,” and offers features like “Stabilized USD-equivalent accounts”—both of which indicate that users do not hold their own private keys. These services require backend infrastructure controlled by the operator, meaning user funds are held on their behalf.
They have a tiered model where if you provide your sms or email, the backup of the seed phrases is made available.
To quote:
Flash is a hybrid custodial wallet, so your backups on your Cash(USD) wallet are automatically encrypted and stored when you add a phone number or email address to Flash App. However, your Bitcoin wallet is completely under your control, and you will need to secure the backup yourself. In order to restore your Cash(USD) wallet in the event that you lose your device, you will to follow our restore process (Import Wallet) and provide your phone number or email address. For your BTC wallet we strongly recommend writing down your backup phrase and storing it in a secure place as soon as possible.
IMPORTANT: If you lose your device and do not have your backup phrase, you will not be able to restore your BTC wallet and your Bitcoin will be lost. Treat your Bitcoin wallet like your savings account, and your Cash(USD) wallet like the cash in your pocket; we recommend that you only store as much cash on Flash as you would carry in your pocket.
The app supported both Bitcoin and lightning. We tested this and was provided with the 12-word seed phrases. This app’s source is available.
Flash is built on top of the Bitcoin and Lightning Networks.
Source: Store
Receive Bitcoin via NFC technology, making transactions as simple as a tap with devices like bolt cards or rings
Source: Store
Seamless integration with Liquid sidechain functionality
Source: GitHub README
Flash is built on top of the Bitcoin and Lightning Networks.
Source: Store description
MIT License Copyright (c) 2021 Galoy Inc Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software
Source: License
Receive Bitcoin via NFC technology, making transactions as simple as a tap with devices like bolt cards or rings
Source: Store description
Product page updated by Daniel Andrei R. Garcia
⚠️ Liquid Network Integration
Liquid Bitcoin is NOT Bitcoin. L-BTC is held by a federation of companies. If a quorum of federation members collude or are compelled, they can seize all L-BTC. If Blockstream alone fails to rotate keys on schedule, they gain unilateral control. Only use Liquid for amounts you'd trust to a corporate consortium.
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.