Muun: Bitcoin Lightning Wallet
Latest release found by WalletScrutiny: 55.11 / 2.16.0
- Developer
- muun (Android)
Muun Wallet, Inc (iPhone) - Released
- Android: 25th April 2017
iPhone: 11th October 2019 - Custody
- Self-custodial: The user holds the keys
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.
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.Distribution
Build Verifications
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:
Android
Legacy verification 2024
App Description
Muun is a self-custodial Bitcoin and Lightning Network wallet for Android, featuring a 2-of-2 multi-signature model that enhances security by storing only one key on the device and providing the other in an exportable Emergency Kit. It supports both on-chain and Lightning payments from a unified interface with dynamic fee estimation based on mempool conditions. The wallet includes Bech32 address support, taproot compatibility, and fee selection options. Recovery is possible using either a written code or email and password, but it does not support standard 12/24-word seed phrases. Muun’s architecture ensures that users retain full control over their funds, with no server-side custody or data access.
This app is source available.
Full SegWit Support
SegWit which is short for “Segregated Witness” was an August 2017 upgrade to the Bitcoin protocol which came with new address types.
Full SegWit Support means that the wallet can both send to and receive to all SegWit address types, including bech32 starting with “bc1…”.
- Receiving to SegWit addresses provides fee savings, as sending these funds is possible using less base-block space. In Bitcoin, transaction fees are proportional to the transaction size in bytes.
- Receiving to bech32 addresses provides more fee savings than P2SH Segwit addresses.
- Sending to SegWit addresses is sometimes required in order to use more modern tools that dropped support for legacy addresses, often because of another core property of SegWit transactions: They are not malleable, meaning that the transaction ID cannot be changed “in transit” (on unconfirmed transactions).
Why we list it for this wallet
The wallet includes Bech32 address support, taproot compatibility, and fee selection options.
Source: App Description
Full Taproot Support
Taproot is an improvement of how Bitcoin transactions work and was activated on 2021-11-12. It uses a new address format, defined in BIP 350.
While some wallets will be able to send to but not receive to Taproot, this feature only tracks those that support both.
- Compatibility: Recipients have to choose an address format and due to efficiency improvements, they will tend more and more to expect being paid to a Taproot address. Wallets supporting this are generally more compatible.
-
Cheaper: Taproot allows for smaller transactions, especially for more complex uses of Bitcoin such as multi signature.
-
More private: As public data of a complicated transaction is usually indistinguishable from that of a simple transactions, special uses “hide in a bigger crowd” and become more private.
- More efficient for offline wallets: Hardware wallets ususally have only a very limited knowledge of the funds being spent, with the user confirming amounts sent but only implicitly the fee being paid. When spending from Taproot, the fee becomes knowable to the offline wallet, making protection against fee overpayment easier.
Initially the privacy will be worse, as using Taproot will make transactions stand out from the crowd.
Why we list it for this wallet
The wallet includes Bech32 address support, taproot compatibility, and fee selection options.
Source: App Description
Multi Signature
Bitcoin allows to define addresses controlled by more than one private key. Two-of-three for example would mean that any two of a list of three private keys would be required to send coins from this address.
With keys from distinct devices or users, an attacker would have to compromise multiple devices or users at once. Multi signature thus allows to protect against one device catching a virus, one wallet having a backdoor (if the multi signature works across different providers’ wallets), one hardware wallet not being trusted (if hardware wallets can be used for multi signature), etc.
- There are no good standards yet for multi signature accounts. This might mean that an account that works with one provider’s wallet won’t load in any other wallet which can complicate recovery should that wallet go out of business.
- Using Multi Signature results in bigger and thus more expensive transactions.
- Using Multi Signature accounts makes it easier for blockchain analysis companies to follow the trail of a wallet.
- Multi Signature accounts require backups of additional descriptors, making financial loss from user error more likely.
Why we list it for this wallet
Muun is a self-custodial Bitcoin and Lightning Network wallet for Android, featuring a 2-of-2 multi-signature model that enhances security by storing only one key on the device and providing the other in an exportable Emergency Kit.
Source: App Description
An issue has been opened at https://github.com/muun/apollo/issues/54
iPhone
Update 2021-07-30: While the Android version made some attempts at reproducibility, the iPhone version, which is in a different code repository, doesn’t claim to be reproducible.
Old Analysis
This provider claims:
Muun is a non-custodial wallet: this means you are in full control of your money. You remain in control of your private keys, which are stored only on your device, using your phone’s secure enclave.
and
Our code is in an open source repository and can be audited by anyone on the Internet.
So they claim the right things and we found their source code but no claims of reproducibility so we conclude this app is not verifiable.
Full SegWit Support
SegWit which is short for “Segregated Witness” was an August 2017 upgrade to the Bitcoin protocol which came with new address types.
Full SegWit Support means that the wallet can both send to and receive to all SegWit address types, including bech32 starting with “bc1…”.
- Receiving to SegWit addresses provides fee savings, as sending these funds is possible using less base-block space. In Bitcoin, transaction fees are proportional to the transaction size in bytes.
- Receiving to bech32 addresses provides more fee savings than P2SH Segwit addresses.
- Sending to SegWit addresses is sometimes required in order to use more modern tools that dropped support for legacy addresses, often because of another core property of SegWit transactions: They are not malleable, meaning that the transaction ID cannot be changed “in transit” (on unconfirmed transactions).
Why we list it for this wallet
Support for Bech32
Source: Store description
Full Taproot Support
Taproot is an improvement of how Bitcoin transactions work and was activated on 2021-11-12. It uses a new address format, defined in BIP 350.
While some wallets will be able to send to but not receive to Taproot, this feature only tracks those that support both.
- Compatibility: Recipients have to choose an address format and due to efficiency improvements, they will tend more and more to expect being paid to a Taproot address. Wallets supporting this are generally more compatible.
-
Cheaper: Taproot allows for smaller transactions, especially for more complex uses of Bitcoin such as multi signature.
-
More private: As public data of a complicated transaction is usually indistinguishable from that of a simple transactions, special uses “hide in a bigger crowd” and become more private.
- More efficient for offline wallets: Hardware wallets ususally have only a very limited knowledge of the funds being spent, with the user confirming amounts sent but only implicitly the fee being paid. When spending from Taproot, the fee becomes knowable to the offline wallet, making protection against fee overpayment easier.
Initially the privacy will be worse, as using Taproot will make transactions stand out from the crowd.
Why we list it for this wallet
The Kit was designed to fit bitcoin's latest scripts, including multisig, lightning and taproot.
Source: Store description
Multi Signature
Bitcoin allows to define addresses controlled by more than one private key. Two-of-three for example would mean that any two of a list of three private keys would be required to send coins from this address.
With keys from distinct devices or users, an attacker would have to compromise multiple devices or users at once. Multi signature thus allows to protect against one device catching a virus, one wallet having a backdoor (if the multi signature works across different providers’ wallets), one hardware wallet not being trusted (if hardware wallets can be used for multi signature), etc.
- There are no good standards yet for multi signature accounts. This might mean that an account that works with one provider’s wallet won’t load in any other wallet which can complicate recovery should that wallet go out of business.
- Using Multi Signature results in bigger and thus more expensive transactions.
- Using Multi Signature accounts makes it easier for blockchain analysis companies to follow the trail of a wallet.
- Multi Signature accounts require backups of additional descriptors, making financial loss from user error more likely.
Why we list it for this wallet
Protected with multi-signature: Muun is a 2-of-2 multi-signature wallet. Your Emergency Kit has both keys, but your phone just one.
Source: Store description
Secure Elements
Secure Elements in Bitcoin wallets refer to dedicated hardware components designed to enhance security. These elements are specialized circuits or chips embedded in the device, providing a fortified environment for storing sensitive data such as private keys. Unlike standard storage, Secure Elements are resistant to tampering and physical attacks, making them an ideal choice for safeguarding cryptographic data and operations. The use of Secure Elements is crucial, especially in hardware and mobile wallets, where the risk of physical theft or tampering is a concern. These elements can effectively shield private keys from a wide range of attacks, including sophisticated ones like side-channel attacks. They ensure that private keys never leave the secure environment, even when signing transactions, offering a higher level of security compared to software-only solutions. While adding a significant layer of security, Secure Elements may pose challenges in terms of wallet recovery. In cases where the device is damaged or lost, retrieving the private keys can be more complex compared to wallets that solely use software-based security measures.
- Enhanced security against physical and sophisticated attacks
- Increased protection for private keys and sensitive data
- Peace of mind knowing that cryptographic operations are performed in a secure, isolated environment
Potential complexities in wallet recovery and dependency on specific hardware.
Why we list it for this wallet
private keys, which are stored only on your device, using your phone's secure enclave.
Source: Existing WalletScrutiny review
Product page updated by Leo Wandersleb, mohammad, keraliss
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.