NextInternalKey

NextInternalKey derives the next internal key for the given key family and stores it as an internal key in the database to make sure it is identified as a local key later on when importing proofs. While an internal key can also be used as the internal key of a script key, it is recommended to use the NextScriptKey RPC instead, to make sure the tweaked Taproot output key is also recognized as a local key.

Source: assetwalletrpc/assetwallet.proto

gRPC

rpc NextInternalKey (NextInternalKeyRequest) returns (NextInternalKeyResponse);

REST

HTTP Method	Path
POST	/v1/taproot-assets/wallet/internal-key/next

Code Samples

gRPC

Javascript

const fs = require('fs');
const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const GRPC_HOST = 'localhost:10029'
const MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
const TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync('assetwalletrpc/assetwallet.proto', loaderOptions);
const assetwalletrpc = grpc.loadPackageDefinition(packageDefinition).assetwalletrpc;
process.env.GRPC_SSL_CIPHER_SUITES = 'HIGH+ECDSA';
const tlsCert = fs.readFileSync(TLS_PATH);
const sslCreds = grpc.credentials.createSsl(tlsCert);
const macaroon = fs.readFileSync(MACAROON_PATH).toString('hex');
const macaroonCreds = grpc.credentials.createFromMetadataGenerator(function(args, callback) {
  let metadata = new grpc.Metadata();
  metadata.add('macaroon', macaroon);
  callback(null, metadata);
});
let creds = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds);
let client = new assetwalletrpc.AssetWallet(GRPC_HOST, creds);
let request = {
  key_family: <uint32>,
};
client.nextInternalKey(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "internal_key": <KeyDescriptor>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the assetwalletrpc/assetwallet.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import assetwallet_pb2 as assetwalletrpc, assetwallet_pb2_grpc as assetwalletstub

GRPC_HOST = 'localhost:10029'
MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

# create macaroon credentials
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
def metadata_callback(context, callback):
  callback([('macaroon', macaroon)], None)
auth_creds = grpc.metadata_call_credentials(metadata_callback)
# create SSL credentials
os.environ['GRPC_SSL_CIPHER_SUITES'] = 'HIGH+ECDSA'
cert = open(TLS_PATH, 'rb').read()
ssl_creds = grpc.ssl_channel_credentials(cert)
# combine macaroon and SSL credentials
combined_creds = grpc.composite_channel_credentials(ssl_creds, auth_creds)
# make the request
channel = grpc.secure_channel(GRPC_HOST, combined_creds)
stub = assetwalletstub.AssetWalletStub(channel)
request = assetwalletrpc.NextInternalKeyRequest(
  key_family=<uint32>,
)
response = stub.NextInternalKey(request)
print(response)
# {
#    "internal_key": <KeyDescriptor>,
# }

REST

Javascript

const fs = require('fs');
const request = require('request');

const REST_HOST = 'localhost:8089'
const MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'

let requestBody = {
  key_family: <integer>, // <uint32> 
};
let options = {
  url: `https://${REST_HOST}/v1/taproot-assets/wallet/internal-key/next`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
  form: JSON.stringify(requestBody),
}
request.post(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "internal_key": <object>, // <KeyDescriptor> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8089'
MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

url = f'https://{REST_HOST}/v1/taproot-assets/wallet/internal-key/next'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
data = {
  'key_family': <uint32>,
}
r = requests.post(url, headers=headers, data=json.dumps(data), verify=TLS_PATH)
print(r.json())
# {
#    "internal_key": <KeyDescriptor>,
# }

Shell

# There is no CLI command for this RPC

Messages

assetwalletrpc.NextInternalKeyRequest

Source: assetwalletrpc/assetwallet.proto

Field	gRPC Type	REST Type	REST Placement
key_family	uint32	integer	body

assetwalletrpc.NextInternalKeyResponse

Source: assetwalletrpc/assetwallet.proto

Field	gRPC Type	REST Type
internal_key	KeyDescriptor	object

Nested Messages

taprpc.KeyDescriptor

Field	gRPC Type	REST Type
raw_key_bytes The raw bytes of the key being identified.	bytes	string
key_loc The key locator that identifies which key to use for signing.	KeyLocator	object

taprpc.KeyLocator

Field	gRPC Type	REST Type
key_family The family of key being identified.	int32	integer
key_index The precise index of the key being identified.	int32	integer