Add a Watch-only Wallet in Bitcoind

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As of bitcoind v10, there is support for watch-only addresses. A bitcoin address is sufficient. The bitcoin-cli command is:

bitcoin-cli importaddress "address" ( "label" rescan )

Where "address" is the address you wish to watch, "label" is an optional label for the the address, and "rescan" is a boolean of whether bitcoind should rescan all previous transactions for activity relating to "address".

The example in bitcoin-cli's documentation of the JSON-RPC command is:

curl --user myusername --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "importaddress", "params": ["myaddress", "testing", false] }' -H 'content-type: text/plain;' http://127.0.0.1:8332/

Release notes for watch-only wallet...

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Hello and welcome back to my blog!

This article talks about the technical implementation details of building a watch only wallet on top of bitcoind - it's aimed at bitcoin / altcoin business owners/developers rather than individuals.

Watch only

Watch only wallets do not contain the private keys for the addresses they're watching, which makes them extremely secure. An attacker who gained access to your watch-only wallet would not be able to withdraw any coins. You cannot spend coins from a watch only wallet directly, but you can get the balance of an address, or export a transaction to be signed externally. This makes them fall into the category of cold storage.

The reference bitcoin client, bitcoind currently does not support watch only wallets, which is a great shame. However, it does expose a nice JSON RPC API which we can use to help us.

Sacrifices

Before we get started it is necessary to explore the sacrifices we make going...

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It has been suggested that this article is merged with Ways_to_store_Bitcoins.

Introduction

Wallet security can be broken down into two independent goals:

Protecting your wallet against loss. Protecting your wallet against theft.

In the case that your current wallet hasn't been protected adequately (e.g. put online with a weaker password):

Making a new secure wallet, using appropriate long-term protection.

For a brief overview see also: Wallet Security Dos and Don'ts

Cold wallets

A cold wallet generates and stores private wallet keys offline on a clean air-gapped computer. Unsigned transactions are generated online, transferred offline for verification and signing, and the signed transaction is transferred online to be transmitted to the Bitcoin network.

This allows funds to be managed offline in Cold storage. Used correctly a cold wallet is protected against online threats, such as viruses and hackers. Cold wallets are similar to...

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Like in real life, your wallet must be secured. Bitcoin makes it possible to transfer value anywhere in a very easy way and it allows you to be in control of your money. Such great features also come with great security concerns. At the same time, Bitcoin can provide very high levels of security if used correctly. Always remember that it is your responsibility to adopt good practices in order to protect your money.

Be careful with online services

You should be wary of any service designed to store your money online. Many exchanges and online wallets suffered from security breaches in the past and such services generally still do not provide enough insurance and security to be used to store money like a bank. Accordingly, you might want to use other types of Bitcoin wallets. Otherwise, you should choose such services very carefully. Additionally, using two-factor authentication is recommended.

Small amounts for everyday uses

A Bitcoin wallet is like a...

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Introduction

Unless you are using a hardware wallet it is strongly recommended to read this page.

Wallet security can be broken down into two independent goals:

Protecting your wallet against loss. Protecting your wallet against theft.

In the case that your current wallet hasn't been protected adequately (e.g. put online with a weaker password):

Making a new secure wallet, using appropriate long-term protection.

For a brief overview see also: Wallet Security Dos and Don'ts

Paper Wallets

Main page: Paper wallet

Paper wallets can be used to store bitcoins offline in non-digital format. Using securely generated paper wallets significantly decreases the chances of your bitcoins being stolen by hackers or computer viruses. Fundamentally, a paper wallet is merely a physical record of a HD wallet private seed.

Hardware wallets

Hardware wallets are a major step to enhanced security and usability.

See the Hardware...

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CONCLUSION

Importing "watch only" addresses (cold storage), creating a wallet in pruned mode and a pruned blockchain and then importing the private key to go from cold to hot storage works just fine in bitcoin-qt (after a restart).

However, when importing "watch only" addresses AFTER creating the blockchain the balances are not visible and require to download the full blockchain again (95 GB).

As far as I understand it this is not necessary, as the balances (not the history) can be obtained from the UTXO set and a new download is not necessary. I made this an issue on Github (and just got a positive feedback).

A possible use case: a user downloads (or gets it from a usb) a 2.5 GB pruned blockchain, checks it (maybe some options or software needs to be developed) and creates a wallet and imports his own addresses and/or private keys WITHOUT HAVING TO CREATE THE PRUNED BLOCHCHAIN HIMSELF, WHICH IS VITAL IN ORDER TO SCALE BITCOIN.

At the moment...

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Watch-only addresses are a Blockchain Wallet feature you can find in the Imported Addresses section of your wallet. In recent updates, we’ve made some improvements to how you can use watch-only addresses, and how the balances of these addresses are reflected in your wallet. In this post we’ll cover details on these updates and how that affects your wallet experience.

What are watch-only addresses?

A watch-only address is a public bitcoin addresses you’ve imported into your wallet. This is a cool, useful feature if you want to monitor activity at a particular bitcoin address. You can import any existing bitcoin address (like this one, for example) into your wallet as a watch-only address, which will incorporate all of its incoming and outgoing transactions into your live transaction feed. You can tell which transactions are for watch-only addresses, because they’ll be labeled as such.

To learn more about the Addresses section in your wallet, including Imported...

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Bitcoin Core version 0.10.0 is now available from:

https://bitcoin.org/bin/0.10.0/

This is a new major version release, bringing both new features and bug fixes.

Please report bugs using the issue tracker at github:

https://github.com/bitcoin/bitcoin/issues

How to Upgrade

If you are running an older version, shut it down. Wait until it has completely shut down (which might take a few minutes for older versions), then run the installer (on Windows) or just copy over /Applications/Bitcoin-Qt (on Mac) or bitcoind/bitcoin-qt (on Linux).

Downgrading warning

Because release 0.10.0 makes use of headers-first synchronization and parallel block download (see further), the block files and databases are not backwards-compatible with older versions of Bitcoin Core or other software:

Blocks will be stored on disk out of order (in the order they are received, really), which makes it incompatible with some tools or other...

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Using the getblock RPC function we can then pull down a JSON encoded block from bitcoind,which looks like this:

{ "hash" : "000000004cabf003eeba1c75e6842a5a098dbb98ebf0c190cdfd46", "confirmations" : 1, "size" : 5164, "height" : 205401, "version" : 2, "merkleroot" : "ebcc75ac9cff8719568ea20e09d39ec0060fdb5cf013b6ce1cd082f779f0de09", "tx" : [ "5405a7a0c1a42538dfd70387dd202b3fe015e28f5c52", "f6977b1aceeb2e4e6a407d61741d75b6a8354c0f5cd4", "f14d21aa726448d0f42abfdb5c8c5fded875b6373fccf6cbb9afff193adf14b3", "94656ee578f0ac91d7ff6bef7953603ab067bc13f636d04ed46d8e9a9fdbf195", "f6481983bdb8d1646c0011a4c8dbcf26844f3d492cf1f9e2e2b710", "da286b224f577e1c94c0788e8f57c5a7073c8a763299dcf7a2833e3c19ee1591", "c5eeb1de3f1bec7a5da8880aea03dfe9c8", "ba0829f62f96dbca3a607b1bb4475416f31ae11cfb7be95a697321", "20d64b1dc51bfe9874343f9dcd8f44d2c6996d53864d67f881f2c68e16e1f426", "ecb3bba37f21abfafa4ba8def7e90b0d40caa7cf0779454ae68a88663e2c90f1", ...

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Treat a paper wallet like a piggy bank: Add funds as often as you like, but only import (or "sweep") your funds once.

How to transfer bitcoins to a paper wallet

Open your live wallet software (e.g. Bitcoin-Qt or Electrum or Mycelium) or web-based wallet (e.g. blockchain.info, coinbase.com) and transfer funds from your live wallet to the public address shown on your paper wallet.

How to withdraw/spend bitcoins using a paper wallet

The way you will access your funds will be to "import" or "sweep" your paper wallet. This effectively transfers the coins from your paper wallet to a live wallet, whether that be electrum, bitcoin-QT, blockchain.info, etc. You should always sweep the complete balance, as it's not safe to try to spend directly from the paper wallet itself.

Virtually any wallet that includes a "import private key" feature will accept the private key hidden under the folds of your paper wallet. However, not 100% of wallets have this...

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Watch-only accounts are just as easy to add as standard sub-accounts: just give us the bitcoin address to monitor for credits and debits. The new account shows up along side your other Coinkite sub-accounts, even though we have no access to those funds.

You can even add multiple addresses per account and we will show you the total! Event notifications work with these accounts, you can receive an SMS (or email) moments after someone deposits into the watched address. Similarly, you can enable notifications when funds move out from the address, even though that was done outside Coinkite! If you are a Developer, you can add new watch only accounts via API.

How to Add Watch Only Account:

Click “Create New Account”Give it a nameSelect “Watch Only”Press “Create Account”

Get your Coinkite wallet FREE...

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Error correction is an interesting suggestion.

If there was 10000 nodes and each stored 0.1% of the blocks, at random,
then the odds of a block not being stored is 45 in a million.

Blocks are stored on average 10 times, so there is already reasonable
redundancy.

With 1 million blocks, 45 would be lost in that case, even though most are
stored multiple times.

With error correction codes, the chances of blocks going missing is much
lower.

For example, if there was 32 out of 34 Reed-Solomon-like system, then 2
blocks out of 34 could be lost without any actual data loss for the network.

As a back of the envelop check, the odds of 2 missing blocks landing within
34 of another is 68/1000000. That means that the odds of 2 missing blocks
falling in the same correction section is 45 * 34 / 1000000 = 0.153%. Even
in that case, the missing blocks could be reconstructed, as long as you
know that...

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The purpose of this tutorial is to show how to setup the Wallet Service. The Wallet Service is the backend for wallets such as BitPay's Copay Multisignature Wallet. The wallet service is very much like the backend for traditional SPV (Simplified Payment Verification) wallets except that the wallet service is much more feature-full. It's recommended to be familiar with running a Bitcore node running before starting this tutorial, please see the Run a Full Node guide for details.

Installing MongoDB

MongoDB is the database for the Bitcore Wallet Service and is the main dependency outside of the Node.js modules. Follow the installation instructions detailed at the MongoDB website, and/or follow details below.

Mac OS X

The easiest way to install MongoDB is to use brew:

brew install update brew install mongodb mkdir -p /data/db sudo chown -R `whoami` /data/db #this assumes that the next step will be run by the current user mongod

Please refer to these...

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Previously: Drupal / Bitcoin BIP 70 / PKI certificates
Also: Ensuring security of funds and preserving anonymity when using Bitcoin for e-commerce

Each Coin Tools payment needs its own Bitcoin address. This is necessary so that it is clear whether or not the payment has been completed. It is also important for preserving anonymity.

In order to participate in the Bitcoin network, a Drupal website must talk to a Bitcoin node. Currently Coin Tools utilises the reference implementation, bitcoind.

bitcoind has wallet functionality built in. In fact, it was originally released as a desktop wallet for Microsoft Windows. By default, bitcoind will pre-generate a pool of 100 pairs of addresses and corresponding private keys. This pool will be increased as necessary.

This presents a number of problems. If data-loss were to occur on the server, the private keys could be unrecoverable and therefore the funds stored on the addresses would be unspendable. If a...

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Contents

Вступ

Wallet security can be broken down into two independent goals:

Protecting your wallet against loss. Protecting your wallet against theft.

In the case that your current wallet hasn’t been protected adequately (e.g. put online with a weaker password):

Making a new secure wallet, using appropriate long-term protection.

Cold wallets

A cold wallet generates and stores private wallet keys offline on a clean air-gapped computer. Unsigned transactions are generated online, transferred offline for verification and signing, and the transaction is signed transferred online to be transmitted to the Bitcoin network.

This allows funds to be managed offline in Cold storage. Used correctly a cold wallet is protected against online threats, such as viruses and hackers. Cold wallets are similar to hardware wallets, except that a general purpose computing device is used instead of a special purpose peripheral.

Hardware...

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Cold Storage For Everyone

Armory makes Bitcoin security best practices accessible to everyone through its unique interface. And most importantly, it’s available for free.

Learn more »

Open Source and Extensible

Armory was created with developers in mind. Armory is a great base for building Bitcoin apps like exchanges and crowdfunding platforms.

Learn more »

Enterprise Consulting Available

Need help managing large Bitcoin balances? We are experts at helping exchanges, trusts, hedge funds, and other large holders of Bitcoin.

Learn more »

BEST BITCOIN WALLET

Armory is the most secure and full featured solution available for users and institutions to generate and store Bitcoin private keys. This means users never have to trust the Armory team and can use it with the Glacier Protocol. Satoshi would be proud!

Users are empowered with multiple encrypted Bitcoin wallets and permanent one-time ‘paper backups’....

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Electrum was created by Thomas Voegtlin in November 2011. Since then a number of developers have contributed to its source code to enhance its features, stability and reliability.

The Electrum wallet is a feature rich Bitcoin Wallet that can be be downloaded from

https://electrum.org

Electrum is a free software both as a client and a server software. Electrum wallet is supported on a wide range of devices. It fits the requiremets and need of a large range of users. For the mobile users it is available as Kivy and the desktop users can use the Qt version. It also supports text mode and command line for advanced usages. Fast speed of loading and operation, Secure and ease of use makes Electrum the wallet of choice for a large number of users. It incorporates a simple payment verification where in Electrum verifies the user transactions in the Bitcoin blockchain. Electrum supports “Cold Storage” wherein the user signs transactions from a computer that is always...
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Electrum Bitcoin wallet for Android.

Secure, feature rich and trusted by the Bitcoin community since 2011.
• Website: https://electrum.org
• Email: electrumdev@gmail.com
• GitHub: https://github.com/spesmilo/electrum
• Support: Please use GitHub or email to report bugs rather than the app rating system.

Features:
• Safe: Your private keys are encrypted and never leave your device.
• Forgiving: Your wallet can be recovered from a secret phrase.
• Instant On: Electrum uses servers that index the Bitcoin blockchain making it fast.
• No Lock-In: You can export your private keys and use them in other Bitcoin clients.
• No Downtimes: Electrum servers are decentralized and redundant. Your wallet is never down.
• Proof Checking: Electrum Wallet verifies all the transactions in your history using SPV.
• Cold Storage: Keep your private keys offline and go online with a watching-only wallet.

Important: In...

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