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README.md

Recover coins from GreenAddress wallets

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For more information on the GreenAddress service, subaccount types and recovery, please read the GreenAddress FAQ

Dependencies for Ubuntu & Debian

$ sudo apt-get update -qq
$ sudo apt-get install python3-pip python3-dev build-essential python3-virtualenv -yqq

Install

$ virtualenv -p python3 venv
$ source venv/bin/activate
$ pip install --require-hashes -r tools/requirements.txt
$ pip install .

Summary

The GreenAddress Recovery Tool allows you to recover coins from your GreenAddress account(s) if you cannot use the normal mechanisms for making payments. This could be due to one of the following scenarios:

  • You lose access to your two factor authentication (2FA) mechanism
  • The GreenAddress service becomes unavailable

There are two recovery scenarios depending on whether the coins are in a GreenAddress 2of2 or a 2of3 subaccount. If you have an nlocktimes.zip recovery file that was emailed to you by the service, then the 2of2 proceedure should be followed.

The recovery tool supports recovering from both types of subaccounts.

2of2 Recovery

Coins held in 2of2 accounts need to be signed by both you and Blockstream Green (also known with the previous name Greenaddress). At the moment, provided you have nLocktime emails enabled in your settings, the service automatically generates special "nLockTime" transactions, pre-signed by Blockstream Green but not spendable until some time in the future (the nLockTime). To recover these coins, refer to the 'nLocktime' section. In the future, thanks to a new type of script (CSV) the coins will be spendable by your keys only after a chosen amount of blocks has passed. To recover these coins, refer to the 'CSV (Check Sequence Verify)' section. Note that, in some cases, it may be needed to follow both procedures to recover all coins.

nLocktime

To recover coins from a 2of2 account you simply wait until each nLockTime transaction becomes spendable (90 days by default), then countersign using the recovery tool and broadcast. The coins are sent to a key derived from your login mnemonics which you can then sweep into any wallet.

You will need:

  1. The latest nlocktimes.zip file sent to your email address from GreenAddress
  2. Your GreenAddress mnemonic
  3. The recovery tool

To run the recovery tool in 2of2 mode:

$ garecovery-cli 2of2 --nlocktime-file /path/to/downloaded/nlocktimes.zip -o garecovery.csv

Enter your mnemonic when prompted. The recovery tool will print a summary of the recovery transactions and also write them to a file garecovery.csv.

WARNING garecovery.csv contains the private keys to which the coins will be sent. Be sure to perform the recovery on a device you trust and take care to delete the recovery csv file securely when you are finished with it.

A sample of the printed summary output is:

mnemonic: <your mnemonic here...>
    tx id lock time      total out                destination address     coin value
--------- --------- -------------- ---------------------------------- --------------
7a00ab...   1139186 830673.85 bits 19G11T26M6xYwbq5UpJPtGrXbsdQyzpCsx 830673.85 bits

total value = 830673.85 bits in 1 utxo

Here you can see the file contains a transaction worth 830673.85 bits, with locktime = 1139186. The locktime indicates the block number that the bitcoin blockchain must reach before the coins are available for recovery. You can find the current block number (also known as the block height) using your local full node or many available online tools, for example https://blockexplorer.com

Once the transactions are spendable they can be broadcast onto the network. The raw transactions are in the csv file, along with the private key for the address they send their coins to. You can broadcast these raw transactions using your full node via RPC or online tools such as:

https://blockexplorer.com/tx/send
https://www.smartbit.com.au/txs/pushtx

CSV (Check Sequence Verify)

Unspent coins locked by CSV scripts (OP_CHECK_SEQUENCE_VERIFY, not to be confused with the file extension .csv) in 2of2 subaccounts are discoverable by scanning the blockchain to look for them. The recovery tool connects to your Bitcoin Core full node in order to perform this scanning for you when recovering.

You will need:

  • A Bitcoin Core full node configured for local RPC access; the node wallet functionality must not be disabled, indeed the coins will be sent to addresses owned obtained from the node.
  • The recovery tool
  • Your Blockstream Green/GreenAddress mnemonic

To run the recovery tool in 2of2-csv mode:

$ garecovery-cli 2of2-csv -o garecovery.csv

Enter your mnemonic when prompted. The recovery tool will print a summary of the recovery transactions and also write them to a file garecovery.csv.

If any recoverable coins were found the tool will display a summary of them on the console and write the details to the output csv file ready for broadcasting using the same steps as detailed above for 2of2 nLocktime.

2of3 Recovery

Note for 0.17 users: it is now possible to specify --ignore-mempool, which makes the procedure much faster (by using scantxoutset). However, as the flag suggests, it does not consider the transactions that are still in the mempool.

In the case of 2of3 subaccounts you hold the mnemonics for 2 keys: the default key used for day to day spending and a backup key used for recovery. Coins held in a 2of3 account can be spent either by signing with your default key and the GreenAddress key under normal circumstances, or by signing with both your default and backup keys for recovery.

Unlike 2of2 where GreenAddress sends nLocktime transactions to you for recovery, unspent coins in 2of3 subaccounts are only discoverable by scanning the blockchain to look for them. The recovery tool connects to your bitcoin core full node in order to perform this scanning for you when recovering.

You will need:

  1. A bitcoin core full node configured for local RPC access
  2. The recovery tool
  3. Your GreenAddress mnemonic
  4. The GreenAddress mnemonic for your 2of3 account
  5. The GreenAddress extended public key (xpub) for your 2of3 account
  6. A destination bitcoin address to send the recovered coins to

Setting up and running a bitcoin node is beyond the scope of this document but instructions are readily available online. Ensure your node is running, fully synced and you are able to connect to the RPC interface. You can verify this using a command like:

/path/to/bitcoin-core/bin/bitcoin-cli getblockchaininfo

Also note that wallet functionality must not be disabled on your node.

Run the recovery tool in 2of3 mode:

$ garecovery-cli 2of3 --destination-address=XXXX -o garecovery.csv --ga-xpub=YYYY

The tool will prompt you for your mnemonic, recovery mnemonic and xpub. You should have noted these details down when you created the 2of3 subaccount.

The tool will then connect to your node to scan for the 2of3 transactions. This may take quite a long time. You can check the scan progress either by looking in the bitcoind log file or in the bitcoin GUI.

If any recoverable coins were found the tool will display a summary of them on the console and write the details to the output csv file ready for broadcasting using the same steps as detailed above for 2of2 subaccounts.

Liquid Recovery

In the case of Liquid subaccounts the outputs are locked by CSV (OP_CHECK_SEQUENCE_VERIFY) scripts. Which means that coins can be spent either by signing with your default key and the Green/GreenAddress key under normal circumstances, or by signing with your default key only after a certain amount of blocks.

Unspent coins in Liquid subaccounts are only discoverable by scanning the blockchain to look for them. The recovery tool connects to your Liquid/Elements core full node in order to perform this scanning for you when recovering.

You will need:

  • A Liquid/Elements core full node configured for local RPC access
  • The recovery tool
  • Your Green/GreenAddress Liquid mnemonic

Instructions to run a Liquid node can be found here. Ensure your node is running, fully synced and you are able to connect to the RPC interface. You can verify this using a command like:

$ /path/to/elements-core/bin/elements-cli getblockchaininfo

Run the recovery tool in CSV mode:

$ garecovery-liquid-cli csv --network=liquid

The tool will prompt you for your mnemonic.

Unlike 2of3, wallet functionality must be available on your node. Indeed the tool will create transactions sending the recovered funds to addresses obtained from the node.

Troubleshooting

If you find any bugs, or have suggestions or patches, please raise them on the garecovery github project.

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GreenAddress recovery tool for 2of2 and 2of3 wallets

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