Wednesday, March 11, 2015

Comparison of Multi-Signature Wallets

Wallet name Platform Full-node N of M Multiple wallets Cold storage Wallet encryption License Other Interesting
Armory Windows / Linux / Mac full node 1-7 of 1-7 yes yes yes AGPL Very feature-rich. Officially still in beta. **
Electrum 2.0 Windows / Linux / Mac thin client 2 of 2-3, also w/ 2FA yes yes yes GPL Feature-rich, 2 factor authentication support **
GreenAddress Web / Mobile / Chrome - 2 of 2 (2FA), 2 of 3 (2FA w/ backup key) yes - yes? private keys not stored on server LGPL All transactions require 2 factor authentication confirmation from the service, implemented with multisig (improved security). Support for nLockTime (releasing funds without requiring confirmation from the service after a set time has passed) **
Bitcore Wallet Suite Linux / Mac? / Win? (written in node.js) full node ? m-of-n yes yes yes MIT Full suite for building client-server (REST API) multisignature, HD bitcoin wallets, contains a command-line client by default. Only recently published *
mSIGNA Windows / Linux / Mac full node (connects to bitcoin core) 1-8 of 1-8 yes yes yes MIT/AGPL *
Copay Web / Mobile / Chrome - 1-4 of 1-6 yes - yes MIT Still in beta, profiles (private keys) can be saved in the cloud or on the device used to create them, made by bitpay * Browser (Fully client side) - 1-15 of 1-15 yes yes, with labor yes MIT runs in browser but fully client side, so can be downloaded and ran locally
Bitcoin Core (the official client) Windows / Linux / Mac full node m-of-n, command-line only in principle command-line only yes MIT The official Bitcoin client. Very well tested but not so feature-rich
CoinKite Web - 1-15 of 1-15 yes (depending on paid plan) - yes proprietary Other nice features, such as a "debit card"
Ninki wallet (1.1+) Chrome - 2 of 3 ? ? ? ? (source in github repo, no LICENSE file) Still in early development, 1.1 unreleased, 2 factor authentication support
Dark wallet (ALPHA!) Chrome - 1-15 of 1-15 ? yes ? ? AGPL In early development, not recommended for use!
Bitcoin Authenticator Windows / Linux / Mac ? only 2FA yes? ? ? ? Still in alpha
Trezor Hardware - ? - - - ?
BitGo Web - m-of-n ? yes - yes? ?

Hover on table to enlarge

The above table shows a comparison of multi-signature (multisig) Bitcoin wallets. Information from the wallets was obtained by testing (all wallets except Bitcore Wallet Suite, Bitcoin Authenticator, BitGo and Trezor were tested at least superficially) and by surveying the web sites of the wallets. Cells marked with dashes were not applicable (e.g. full node for a web wallet) and cells with question marks contain data that was either unclear or not found. Should you notice any errors or know about multi-signature wallets not in the table, please leave a comment and we will take them into account!

For a quick recap, a multi-signature Bitcoin address differs from a “traditional” addresses in that transactions from the address require signatures from multiple different private keys. For an example a 2-of-3 multisig address has 3 associated private keys, 2 of which must be used to sign each transaction from the address (in general, the notation m-of-n means m signatures required from n associated private keys). Uses for multi-signature addresses include enhanced security (some addresses can be kept in cold storage or secured with two-factor authentication), supporting wallets with multiple owners (think 1-of-2 for a couple’s spending account; or 2-of-3 for a child’s savings account where confirmation from either parent and a child, or from both parents is required for each spending), and use in escrow services (2-of-3 with two parties and a mediator).

A person looking for a multi-signature wallet has several options, based on their needs. Common questions one should ask from themselves when selecting a wallet include the following:

  • What platform does the wallet need to run on? In practice, this usually translates to “Do I prefer a web-based or software-based wallet?”
  • If going for a software-based wallet, do I prefer a full-validation (full node) or a thin client wallet? Full node wallets require download the whole Block chain, resulting in a larger start up time and space requirements, but offer more control and an additional layer of security in return.
  • In what way am I going to use the multi-signature features of Bitcoin? Many wallets offer only a limited range for m and n (in m-of-n). Some wallets also have built-in two-factor authentication support, implemented using multisig.
  • What other features do I have in mind? Common requirements include wallet encryption (supported by virtually every software out there) and cold storage support (maintaining a wallet on a machine that’s not connected to internet to store Bitcoins and sign transactions, using another machine to broadcast them and to view transaction history)

Wallets that offer the best of a various combination of requirements are marked with stars in the “interesting” column of the table. These include:

  • Software wallet / Large m-of-n: Armory or mSIGNA (also maybe Bitcore Wallet Suite)
  • Software wallet / Thin client: Electrum (see this post for an introduction to Electrum)
  • Web wallet / Insane privacy features: GreenAddress
  • Web wallet / Large m-of-n: Copay
  • Cold storage support: Armory, Electrum or mSIGNA
  • Building my own wallet: Bitcore Wallet Suite

Feel free to post your own experiences and recommendations in the comment section of this post!

Friday, February 13, 2015

Thin wallets with Electrum

Electrum ( is an open-source, light-weight Bitcoin client, available on Windows, Linux, OSX and Android. This post aims to give the reader a quick introduction to its usage and features.

Full-node Bitcoin clients, like the official Bitcoin Core client, maintain a copy of the whole blockchain on the machine the client is installed on. By contrast, light-weight clients such as Electrum rely on a server to provide the transaction history for a wallet and to broadcast new transactions to the bitcoin network. This means that the client can skip downloading and synchronizing the whole blockchain (over 28GB at the time of writing), resulting in virtually no startup time and much, much lower space requirements.

To begin using Electrum, download the program from On first use, you’re prompted to either create a new Bitcoin wallet, restore an existing one from a seed or create a read-only copy of an existing one.

Choosing “create a new wallet” automatically generates a wallet from random data, and gives you a seed that can be used to restore the wallet in case of computer error. Write down the seed and store it in a safe place!

Electrum supports encrypting the private keys associated with a wallet using the AES-256-CBC algorithm. Create a password for the wallet if you wish to do so!

In the next step, you’re asked to either auto-connect to an Electrum server or to pick one yourself. Either choice should be fine, as the only place where the client has to trust the server is providing the transaction history. The server has no knowledge of the client’s private keys, so there’s no risk of a malicious server stealing a client’s bitcoins, though it theoretically possible (if unlikely) for the server to provide an incorrect history of previous transactions for the client.
As of 2015, LocalBitcoins hosts an Electrum server,, which is available using the SSL (port 50002) or TCP (port 50001) protocols.

After connecting to the server, you should get a window with your transaction history (empty in case of a new wallet) and a green light in the bottom-right corner. In case the light is red or the top-left corner reads “not connected”, click the light button and select another server.

And you’re all set go! Other features of Electrum include supporting multiple receiving addresses per wallet, synchronization between different computers and cold storage support. For a full list, and more details about the software, see

Wednesday, September 17, 2014

Marketing Guru? Earn BTC With the LocalBitcoins Affiliate Program!

We just improved LocalBitcoins Affiliate Program a little bit. Now you can get a CSV, which includes information about your converted users. Also a short list of your latest converted visits are included on the affiliate page. Using this info, you can improve your targeting.

Next we plan to implement a tracking pixel for the affiliate program. If you have ideas or feedback related to the affiliate program, comment below!

Monday, September 8, 2014

Accept bitcoin - send invoices, get paid in bitcoin

You can now use LocalBitcoins to accept bitcoins and send bitcoin invoices to your customers. LocalBitcoins has opened Merchant tools section on the site where you can send and manage  invoices.

The invoiced amount to pay can be denominated in any currency. When the recipient opens the invoice, the price is converted to bitcoins using the current exchange rate.

Each invoice has a unique bitcoin address as the payment reference. The payment can be made with any bitcoin wallet, including QR code compatible mobile wallets.

Tuesday, September 2, 2014

Easier reporting of suspicious user activity

LocalBitcoins site has now a new user reporting feature. You can find the user reporting link from the public user profile page. The new feature makes it easier to report suspicious users, though this option has been always available through the support ticket system.

LocalBitcoins support team checks the reported users and may take necessary action to suspend the user account if there is evidence of breaking the site rules and good trade etiquette. Potential reasons to report a user may include
  • Fraudulent activity
  • Violating LocalBitcoins terms of service
  • Misleading information
  • Abuse

Monday, August 25, 2014

Buying and Selling Steam, Amazon, Apple etc Gift Cards on

Gift cards are a nice way to buy stuff froom your favourite store, which doesn't accept bitcoin yet. There has been some gift card trading on LocalBitcoins, but now we have added couple of new features which should make gift card trading much easier.
Contacters can select the amount with dropdown.

Several Gift Card types have been added, you can also select the generic option and name your own.

Type the nominations as comma-separated list.

Remember to add "Track liquidity" to remove your sellable amount automatically as orders roll in.

Questions, comments, suggestions? Happy trading!

Monday, August 11, 2014

LocalBitcoins ATM:s comes out of the oven and goes on the tour

It has been a long time since there have been any news regarding our ATM project which aims to provide automatization for converting cash to bitcoins and vice versa. Another perks of the Localbitcoins ATM:s are the moderate price and the fact that the device works completely offline. ATM:s are integrated to Localbitcoins website, and the actual bitcoin trade happens on; the ATM only takes care about the fiat handling.

There have been two beta versions of these ATM:s in real life testing at the center of Helsinki, Finland. One of them is in a bitcoin accepting restaurant and another one in 24h kiosk. So far there haven't been any major problems, and minor ones have been carved out during the testing process. If you are visiting Helsinki, you can find those ATM:s from here, and here.

Expect to see more of these ATM:s soon, since we are getting our first production batch out soon, and we are putting one of them on the bitcoin tour, held by Finnish bitcoin company They will be driving around Finnish archipelago and testing how well Localbitcoins bitcoin ATM performs on the road.

Eventually you will be able to purchase these ATM:s directly from Localbitcoins website. The price of the ATM's is 1500 eur + VAT and shipping costs.

Specifications of the ATM

Buying process: Buyer feeds banknotes to the machine, and gets a secret code in return. The code is used to claim the corresponding amount of bitcoins to your account. The exchange rate is defined at the moment the code is used.

Selling process: Seller logs in to his/her localbitcoins account, and goes to the URL of the ATM he/she aims to use for withdrawal. The seller selects the amount he/she wants to withdraw from a dropdown menu. After selecting the withdrawal amount, corresponding amount of bitcoins are reduced from the seller's localbitcoins wallet and the user will receive a code, which is given to the ATM through the keyboard. After the code has been inserted, the ATM will give corresponding amount of notes to the customer.

Capacity: Capacity: note recycling unit can hold 30 bills and cash box 300 bills.

Accepted bills: All banknotes where the size is inside of the range (width) 60-82 millimeters, and (length) 115-150 millimeters. The device can accept 6 different kind of bills from the selected currency. The device can be programmed to handle almost any known currency, but only one can be used at the time.

Size(w/h/d): 318 x 340 x 264 millimeters

Display: 87.3 x 41.8 mm one color lcd display

Weight: 15 kg