Last updated on March 4th, 2018 at 03:03 pm
Looking for a good Bitcoin wallet for your phone? I was too, before my recent overseas trip to 99Bitcoins’ headquarters (each of us works from a different country). I needed a secure, reliable wallet – ideally one with an effective stealth mode to keep my bitcoins hidden from prying border guards or sneaky pickpockets. The , true to its tagline of “a Bitcoin wallet for the streets,” was well-suited to this role.
Samourai Wallet Basics
Samourai is a devices, with an iOS version currently . The wallet is coded in Java and is still in the alpha stage, although a 1.0 release is expected soon (as in 2018 sometime). As mentioned, the wallet is focused on privacy and security, with support for IP address anonymization through support for (VPNs) and TOR (The Onion Router – accessible on Android via ).
Samourai is also notable for being one of the earliest mobile wallets to incorporate . Such support lowers transaction costs (for Samourai and other users) while paving the way for future . Lightning is likely to become an extremely desirable feature for all mobile wallets for its retail applications.
It’s clear from their wallet design and (particularly their unwavering resistance to the ) that the Samourai developers work in close accordance with the foundational Bitcoin principles of decentralization, openness, security, fungibility and financial privacy.
Although Samourai doesn’t support , it does allow you to maintain multiple accounts. Multi-accounts can be helpful to, for example, separate business from personal transactions but no multisig means that jointly-controlled accounts aren’t possible. Various Bitcoin exchange rates are accessible within the wallet to help with your monetary calculations.
Samourai’s interface is clear and straightforward, without frills.
The Samourai Stealth Feature
The Samourai wallet contains a great, unique feature: in Stealth Mode, the Samourai shortcut disappears from your mobile’s desktop. To activate the wallet, the correct PIN must be dialed like a phone number. While a knowledgeable investigator with access to your phone will still be able to determine that Samourai is installed, this trick will conceal your wallet from casual or low-info snoopers.
Fee and Transaction Features
In terms of transactional economy, Samourai has many other useful features. The wallet monitors network conditions to better suggest an appropriate “smart fee.” Custom fees may also be set by advanced users who wish to handle this aspect themselves. Undershooting in your fee estimation isn’t a problem either, as the wallet supports Replace By Fee. RBF allows a fee which is set too low to be confirmed timeously to be easily bumped up, any number of times.
Combined, the above features really help to keep transaction fees to a minimum. That’s especially important for a mobile wallet, on which one should store only small amounts of value.
Child Pays For Parent (CPFP) transactions are also supported by Samourai. This useful function works to release any incoming transactions due to insufficient fees. A stuck transaction can be extremely inconvenient for time-sensitive business so, even though CPFP can be expensive, it’s a great feature to have on the go.
Apart from the aforementioned support for Tor and VPNs which cloak your IP address, Samourai contains numerous features which will obscure your Bitcoin balance and transaction history from blockchain analysis. With each spend, you may select the desired level of transaction obfuscation.
By default, Samourai Wallet will:
- Supply you with a for each new payment you receive. This prevents address re-usage; a practice which allows anyone who knows your address to learn all the past and future transactions associated with that address, as well as its balance.
- of you get back according to the type of wallet you’re sending to, either SegWit or non segwit.
- Randomize the number of “change” outputs associated with each transaction made. This plus the above type-matching is done to minimize address linkage through common change addresses.
- Employ to minimize the amount of references to previous transactions from your wallet, decreasing the traceable metadata produced by your wallet.
Bottom line – Samourai makes it harder to connect the dots between your different addresses.
Optionally, you may enable Samourai’s unique . While this costs an extra $2.50 plus additional mining fees, it’s a great way to disguise the origin of your payment. As the name implies, your spending transaction is bounced through a series of 4 extra addresses en-route to its final destination.
Samourai also has the unique ability to use . These allow anyone else using this feature to send you bitcoins without knowing your actual address; they only require your payment code. This code may be reused without degradation of privacy as it can’t be linked to addresses. However, as this option isn’t widely-supported by other wallets, its applications are fairly limited.
Unfortunately, Samourai may only be obtained from the Google Play store at present. As Google has become synonymous with surveillance, this is less than ideal. However, as from , Samourai will be available in , the open source and privacy-respecting Android app repository.
All private keys are stored on your phone in an encrypted format and are never transmitted. Samourai is , meaning that a single seed phrase (which you must accurately record and securely backup) is used to generate (and restore, if need be) all your private keys and their associated Bitcoin addresses.
Samourai Wallet also contains a function to ; a critical though often overlooked aspect of backup management.
Samourai requires you to use a 5 to 8 digit PIN in order to approve transactions. The arrangement of the digits is randomized for each entry, to defeat any screen logging malware. Ensure when entering the PIN that no person or device can observe the process.
A standout feature of Samurai is that it enables you to connect a trusted Bitcoin Core . This lets Samurai receive blockchain data directly , but note that a VPN is required for this option.
As for support, unfortunately Samurai does not yet support this. Apparently this is being – at least for Trezor devices – and should be available in a future release.
Another interesting “power user” feature in Samurai are . By enabling this (and optionally limiting it to a specified phone number), an SMS containing your PIN, when sent to your phone, will instruct Samurai to either self-destruct or reply with your wallet’s backup seed phrase. In the event that someone steals your phone, you could use these commands to first retrieve your funds and then deny the thief access to them. Samourai can even SMS a specified number if the phone it’s installed on has its SIM switched out – thus you can still send Remote Commands to a changed number.
Warning: I’d advise experimenting with the “wipe” Remote Command before funding the wallet. As for the “backup” command, note that if it sends your seed phrase unencrypted it could be trivially intercepted, in which case the wallet’s security would be fully compromised. Don’t rely on this feature, rather backup your seed upon initialization!
Like a Swiss army knife, Samourai combines many useful tools in a single, well-designed package. Similar to the , basic tools are easy for newcomers to use and more advanced tools are available for those who need them.
Samourai is a good wallet and I’m pretty confident that it’ll become a great wallet with future updates. In fact, the only reason that I haven’t yet completely replaced my old with Samourai is the latter’s lack of hardware wallet support (which is planned) and an integrated peer-to-peer exchange (which is not).
- Great privacy features
- Excellent fee management system
- A variety of advanced features
- Relatively new and untested
- No hardware wallet support