scan_for_unspent_grin_outputs.py

# This demonstrates how to use the secp256k1-zkp-mw Python module, https://github.com/grinventions/secp256k1-zkp-mw, to find all the unspent Grin outputs belonging to a wallet. This code lacks any error checking. A wallet's rewind hash can be obtained by running the command `grin-wallet rewind_hash` with the Grin CLI wallet, https://github.com/mimblewimble/grin-wallet.


# Imports
from secp256k1_zkp_mw import *
from hashlib import blake2b
import requests


# Constants

# Rewind hash
REWIND_HASH = bytes.fromhex('99d92c1264de3edab618eeeb024533447c30c4d6549d70efc745fe385bd2862b')

# Server
SERVER = 'https://grinnode.live:3413'


# Functions

# Format number
def formatNumber(number):

    # Return formatted number
    return '{:.9f}'.format(number / 1E9).rstrip('0').rstrip('.')


# Main function

# Create context
context = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY | SECP256K1_CONTEXT_SIGN)

# Get the tip height from the node
tipHeight = requests.post(SERVER + '/v2/foreign', json = {
    'jsonrpc': '2.0',
    'id': 1,
    'method': 'get_tip',
    'params': []
}).json()['result']['Ok']['height']

# Display start message
print('Scanning up to height %d for unspent outputs belonging to the wallet with the rewind hash %s. This may take a while.' % (tipHeight, REWIND_HASH.hex()))

# Get the PMMR indices from the genesis block to the tip height from the node
pmmrIndices = requests.post(SERVER + '/v2/foreign', json = {
    'jsonrpc': '2.0',
    'id': 1,
    'method': 'get_pmmr_indices',
    'params': [
        0,
        tipHeight
    ]
}).json()['result']['Ok']

# Get start and end indices from the PMMR indices
startIndex = pmmrIndices['last_retrieved_index']
endIndex = pmmrIndices['highest_index']

# Go through all unspent outputs in the PMMR indices range
while True:

    # Get the next group of unspent outputs from the node
    unspentOutputs = requests.post(SERVER + '/v2/foreign', json = {
        'jsonrpc': '2.0',
        'id': 1,
        'method': 'get_unspent_outputs',
        'params': [
            startIndex,
            endIndex,
            1000,
            True
        ]
    }).json()['result']['Ok']

    # Go through all unspent outputs in the group
    for unspentOutput in unspentOutputs['outputs']:

        # Get commit and proof from the unspent output
        commit = bytes.fromhex(unspentOutput['commit'])
        proof = bytes.fromhex(unspentOutput['proof'])

        # Get rewind nonce for the commit
        rewindNonce = blake2b(REWIND_HASH, digest_size = 32, key = commit).digest()

        # Check if the unspent output belongs to the wallet
        internalCommit = secp256k1_pedersen_commitment_parse(context, commit)
        outputData = secp256k1_bulletproof_rangeproof_rewind(context, proof, 0, internalCommit, secp256k1_generator_const_h, rewindNonce, None)

        if outputData is not None:

            # Get amount from the output data
            amount = outputData[0]

            # Display unspent output found message
            print('Found an unspent output with %s Grin at height %d.' % (formatNumber(amount), unspentOutput['block_height']))

    # Check if no more unspent outputs exist in the range
    if unspentOutputs['highest_index'] <= unspentOutputs['last_retrieved_index']:

        # Break
        break

    # Update start index
    startIndex = unspentOutputs['last_retrieved_index'] + 1

# Display end message
print('Done scanning for unspent outputs.')

# Destroy the context
secp256k1_context_destroy(context)