Bitcoins Dark Wallet Has a New Challenger: Samourai

Ever since Dark Wallet was first announced, in September of 2013, it has hogged the spotlight as Bitcoin’s underground wallet. Made for dark web users and those otherwise concerned with staying private online, user friendliness was one of it’s central features. But, few people missed that this wallet was being created for the central purpose of keeping your identity as private as it possibly could while making bitcoin transactions. Instantly hailed by privacy advocates and simultaneously demonized in the press, Dark Wallet has remained the undisputed bad boy of bitcoin wallets, at least until now.

In May 2014, a full year after Dark Wallet front man Cody Wilson made international headlines for firing the world’s first 3D printed gun, Cody and partner Amir Taaki released the open source code for the first version of their wallet, Dark Wallet Alpha. It includes some interesting features not seen in any other wallet before, such as identity profiles, a chat lobby, coin mixing and stealth wallet addresses.

Eight versions and three rounds of successful crowdfunding campaigns later, the wallet is more functional than ever. But, it still exists only as a Chrome Browser plugin, and is still labeled an alpha version, that clearly warns users to be careful. The website alerts users that it is not stable and you could lose all of your bitcoins at any time while using it.

Perhaps sensing an opportunity in Dark Wallet’s delay, or maybe it’s lack of a mobile platform, a team of anonymous coding "Samourais," as they call themselves, have put forth their own black-themed, privacy-centric wallet. The first version was released for android last week, on May 7. Their Samourai wallet is described as "a bitcoin wallet made for the streets."

“[Samourai wallet is] a modern bitcoin wallet hand forged to keep your transactions private, your identity masked, and your funds secure."
— – Samourai

Besides the French spelling of its name, the largest difference in Samourai wallet is that it appears to be just as focused on Security as it is Privacy. With never-before-seen wallet features like a stealth mode and a remote self-destruct button via SMS, it’s clearly made with personal security in mind, protecting its user’s bitcoins against being taken by muggers, pickpocketers, the authorities, and even simply losing your phone.

Although we know very little about the developers of Samourai wallet, other than they likely speak French, they claim to be developing it for many of the same reasons that Wilson and Taaki are making Dark wallet.

"We are privacy activists who have dedicated our lives to creating the software that Silicon Valley will never build, the regulators will never allow, and the VC’s will never invest in. We build the software that Bitcoin deserves."
— – Samourai

If the two wallets existed on the same platform, you’d likely be forgiven for mistaking Samourai for Dark Wallet, at first glance. The dark-gray-on-black color scheme is very similar to Dark Wallet’s looks, but the similarities end there. For one, Samourai is exclusively for Android phones at this time, while Dark Wallet is only available in Chrome web browsers.

Coin mixing is handled a little differently on Samourai than it was on Dark Wallet. Although the process is highly technical, a Samourai blog post describes how the coin mixing uses a trustless system, never using any 3rd parties nor servers. This ensures that the sending address is properly mixed with the change addresses, obfuscating the amount being sent in each transaction.

Not only are the number and position of these change addresses randomized, but they claim that the wallet will never re-use any addresses for sending, and will never link previous change outputs in a transaction. Together, this makes tracking transactions back to users extremely difficult for anyone watching the blockchain.

Samourai allows you to backup and restore your wallet, as well as choose your favorite blockchain explorer to use as a reference inside the wallet. In the future it will allow you to choose your own source of exchange rate, which is currently locked into the LocalBitcoins price. NFC payments are also available with Samourai wallet, and can be enabled in the settings menu.

A lot of Samourai’s additions involve its’ unique SMS abilities. If a smartphone is stolen, for instance, one quick SMS message with the proper command can retrieve your Hierarchical Deterministic seed phrase, allowing you to regenerate your entire wallet elsewhere. Better yet, this seed phrase is worthless without knowing your wallet password.

“Our wallet enforces the use of a BIP 39 Passphrase when you create your wallet. This means we can relay your HD seed over SMS without worry. Your HD seed is worthless without your passphrase.”
— – SamouraiWallet on Reddit

After moving your wallet, you’d very likely want to erase the existing wallet off of the stolen phone. Another SMS message and command will completely wipe the entire application off the phone, leaving no trace of it behind.

There is even a “switch alert” built into the wallet that will send out an SMS message automatically when a thief switches the phone’s SIM card, and therefore phone number, before you can send your SMS. The alert will send you the new phone number, so that you can send your ‘move’ and ‘wipe’ SMS messages to it instead.

Perhaps the most powerful new feature of Samourai wallet is its stealth mode. With one single touch you can hide Samourai on the device. Anyone picking up the smartphone afterward won’t see its icon and searching through the installed apps list wont find any trace of it. That is until you call “**[Your PIN code]#” to reveal it again. You can also select if you’d like the wallet to accept SMS commands or not while it is in stealth mode.

Encryption of the wallet is also impressive. At installation Samourai locally encrypts itself using AES-256 encryption, protecting all of the keys inside of it. A strong passphrase is required to gain access, and all bitcoin private keys are created and stored inside the encrypted area. Although they have not integrated Multi-signature wallets yet, this level of security would seem to outshine Dark Wallet’s encryption, based on the fact that their private keys must go off the device to an ‘obelisk’ server, which hypothetically could allow for a hacker intercept during transit.

"The coins are fully controlled by the user at all times. The private keys are stored encrypted on the device and are never communicated to any servers. There currently is not a multi-sig feature, mostly because Samourai is designed to a mobile street wallet, but we see multi-sig as a tool in our back pocket to create some really interesting features down the road."
— – SamouraiWallet

Dark Wallet still has a strong lead on Samourai in these areas.They natively support multi-sig addresses, and use Stealth Addresses. These further anonymize the transactions inside Dark Wallet to a level far above coin mixing alone.

But neither service has integrated with TOR yet, the infamous anonymity network. Although both will allow you to use Virtual Private Networks, which allows some basic IP address protection, TOR has proven difficult to integrate with these wallets.

“We are actively looking at Tor support. VPN and Tor are not mutually exclusive and many users are not Tor-savvy but do know a bit more about VPN. Just as our remote commands are optional, we are working on network anonymity solutions that will appeal to a wide range.”
— – SamouraiWallet

While both wallets claim to be in an alpha version, Dark Wallet warns people against storing large amounts of bitcoin, but their code is fully open-source. Samourai is a closed alpha, and they don’t provide any disclaimers. When asked why the source code has not been made open yet SamouraiWallet replied,  "We are open sourcing our code once we conclude closed beta."

This makes neither wallet truly ready for their intended purpose, and perhaps it is equally as risky to keep your bitcoins in both.

Although it’s still too early to declare a winner in the race to be the wallet with the most privacy, it is clear that certain users will prefer one wallet to the other. For instance, if you need a private wallet for on the go, Samourai should be considered. But users that have the absolute highest needs for privacy should be looking at Dark Wallet, at least for now.