adds jsonrpc_channel_sign signing api

lbry/extras/daemon/daemon.py

@@ -21,6 +21,8 @@ import base58
 from aiohttp import web
 from prometheus_client import generate_latest as prom_generate_latest, Gauge, Histogram, Counter
 from google.protobuf.message import DecodeError
+
+from lbry.crypto.hash import sha256
 from lbry.wallet import (
     Wallet, ENCRYPT_ON_DISK, SingleKey, HierarchicalDeterministic,
     Transaction, Output, Input, Account, database
@@ -2788,6 +2790,40 @@ class Daemon(metaclass=JSONRPCServerType):
 
         return tx
 
+    @requires(WALLET_COMPONENT)
+    async def jsonrpc_channel_sign(
+            self, channel_name=None, channel_id=None, hexdata=None, channel_account_id=None, wallet_id=None):
+        """
+        Signs data using the specified channel signing key.
+
+        Usage:
+            channel_sign [<channel_name> | --channel_name=<channel_name>]
+                         [<channel_id> | --channel_id=<channel_id>] [<hexdata> | --hexdata=<hexdata>]
+                         [--channel_account_id=<channel_account_id>...] [--wallet_id=<wallet_id>]
+
+        Options:
+            --channel_name=<channel_name>            : (str) name of channel used to sign (or use channel id)
+            --channel_id=<channel_id>                : (str) claim id of channel used to sign (or use channel name)
+            --hexdata=<hexdata>                      : (str) data to sign, encoded as hexadecimal
+            --channel_account_id=<channel_account_id>: (str) one or more account ids for accounts to look in
+                                                             for channel certificates, defaults to all accounts.
+            --wallet_id=<wallet_id>                  : (str) restrict operation to specific wallet
+
+        Returns: {}
+        """
+        wallet = self.wallet_manager.get_wallet_or_default(wallet_id)
+        assert not wallet.is_locked, "Cannot spend funds with locked wallet, unlock first."
+        signing_channel = await self.get_channel_or_error(
+            wallet, channel_account_id, channel_id, channel_name, for_signing=True
+        )
+        digest = sha256(unhexlify(hexdata))
+        signature = signing_channel.private_key.sign_digest_deterministic(digest, hashfunc=hashlib.sha256)
+        return {
+            "signature": hexlify(signature),
+            "digest": hexlify(digest),
+            "signing_channel": signing_channel
+        }
+
     @requires(WALLET_COMPONENT)
     async def jsonrpc_channel_abandon(
             self, claim_id=None, txid=None, nout=None, account_id=None, wallet_id=None,

tests/integration/blockchain/test_claim_commands.py

@@ -5,11 +5,13 @@ import asyncio
 from binascii import unhexlify
 from urllib.request import urlopen
 
+import ecdsa
+
 from lbry.error import InsufficientFundsError
 
 from lbry.extras.daemon.daemon import DEFAULT_PAGE_SIZE
 from lbry.testcase import CommandTestCase
-from lbry.wallet.transaction import Transaction
+from lbry.wallet.transaction import Transaction, Output
 from lbry.wallet.util import satoshis_to_coins as lbc
 
 
@@ -1004,6 +1006,22 @@ class ChannelCommands(CommandTestCase):
         self.assertItemCount(await self.daemon.jsonrpc_channel_list(account_id=self.account.id), 2)
         self.assertItemCount(await self.daemon.jsonrpc_channel_list(account_id=account2_id), 1)
 
+    async def test_sign_hex_encoded_data(self):
+        data_to_sign = "CAFEBABE"
+        # claim new name
+        await self.channel_create('@someotherchan')
+        channel_tx = await self.channel_create('@signer')
+        channel_id = self.get_claim_id(channel_tx)
+        signature1 = await self.out(self.daemon.jsonrpc_channel_sign(channel_name='@signer', hexdata=data_to_sign))
+        signature2 = await self.out(self.daemon.jsonrpc_channel_sign(channel_id=channel_id, hexdata=data_to_sign))
+        self.assertEqual(signature2, signature1)
+        key = unhexlify(channel_tx['outputs'][0]['value']['public_key'])
+        signature = signature1["signature"]
+        r = int(signature[:int(len(signature)/2)], 16)
+        s = int(signature[int(len(signature)/2):], 16)
+        signature = ecdsa.util.sigencode_der(r, s, len(signature)*4)
+        self.assertTrue(Output.is_signature_valid(signature, unhexlify(signature1["digest"]), key))
+
     async def test_channel_export_import_before_sending_channel(self):
         # export
         tx = await self.channel_create('@foo', '1.0')