Initial Vexta Core v0.1.0 release

contrib/signet/README.md

@@ -0,0 +1,83 @@
+Contents
+========
+This directory contains tools related to Signet, both for running a Signet yourself and for using one.
+
+getcoins.py
+===========
+
+A script to call a faucet to get Signet coins.
+
+Syntax: `getcoins.py [-h|--help] [-c|--cmd=<digibyte-cli path>] [-f|--faucet=<faucet URL>] [-a|--addr=<signet bech32 address>] [-p|--password=<faucet password>] [--] [<digibyte-cli args>]`
+
+* `--cmd` lets you customize the digibyte-cli path. By default it will look for it in the PATH
+* `--faucet` lets you specify which faucet to use; the faucet is assumed to be compatible with https://github.com/kallewoof/digibyte-faucet
+* `--addr` lets you specify a Signet address; by default, the address must be a bech32 address. This and `--cmd` above complement each other (i.e. you do not need `digibyte-cli` if you use `--addr`)
+* `--password` lets you specify a faucet password; this is handy if you are in a classroom and set up your own faucet for your students; (above faucet does not limit by IP when password is enabled)
+
+If using the default network, invoking the script with no arguments should be sufficient under normal
+circumstances, but if multiple people are behind the same IP address, the faucet will by default only
+accept one claim per day. See `--password` above.
+
+miner
+=====
+
+You will first need to pick a difficulty target. Since signet chains are primarily protected by a signature rather than proof of work, there is no need to spend as much energy as possible mining, however you may wish to choose to spend more time than the absolute minimum. The calibrate subcommand can be used to pick a target appropriate for your hardware, eg:
+
+    cd src/
+    MINER="../contrib/signet/miner"
+    GRIND="./digibyte-util grind"
+    $MINER calibrate --grind-cmd="$GRIND"
+    nbits=1e00f403 for 25s average mining time
+
+It defaults to estimating an nbits value resulting in 25s average time to find a block, but the --seconds parameter can be used to pick a different target, or the --nbits parameter can be used to estimate how long it will take for a given difficulty.
+
+To mine the first block in your custom chain, you can run:
+
+    CLI="./digibyte-cli -conf=mysignet.conf"
+    ADDR=$($CLI -signet getnewaddress)
+    NBITS=1e00f403
+    $MINER --cli="$CLI" generate --grind-cmd="$GRIND" --address="$ADDR" --nbits=$NBITS
+
+This will mine a single block with a backdated timestamp designed to allow 100 blocks to be mined as quickly as possible, so that it is possible to do transactions.
+
+Adding the --ongoing parameter will then cause the signet miner to create blocks indefinitely. It will pick the time between blocks so that difficulty is adjusted to match the provided --nbits value.
+
+    $MINER --cli="$CLI" generate --grind-cmd="$GRIND" --address="$ADDR" --nbits=$NBITS --ongoing
+
+Other options
+-------------
+
+The --debug and --quiet options are available to control how noisy the signet miner's output is. Note that the --debug, --quiet and --cli parameters must all appear before the subcommand (generate, calibrate, etc) if used.
+
+Instead of specifying --ongoing, you can specify --max-blocks=N to mine N blocks and stop.
+
+The --set-block-time option is available to manually move timestamps forward or backward (subject to the rules that blocktime must be greater than mediantime, and dates can't be more than two hours in the future). It can only be used when mining a single block (ie, not when using --ongoing or --max-blocks greater than 1).
+
+Instead of using a single address, a ranged descriptor may be provided via the --descriptor parameter, with the reward for the block at height H being sent to the H'th address generated from the descriptor.
+
+Instead of calculating a specific nbits value, --min-nbits can be specified instead, in which case the minimum signet difficulty will be targeted. Signet's minimum difficulty corresponds to --nbits=1e0377ae.
+
+By default, the signet miner mines blocks at fixed intervals with minimal variation. If you want blocks to appear more randomly, as they do in mainnet, specify the --poisson option.
+
+Using the --multiminer parameter allows mining to be distributed amongst multiple miners. For example, if you have 3 miners and want to share blocks between them, specify --multiminer=1/3 on one, --multiminer=2/3 on another, and --multiminer=3/3 on the last one. If you want one to do 10% of blocks and two others to do 45% each, --multiminer=1-10/100 on the first, and --multiminer=11-55 and --multiminer=56-100 on the others. Note that which miner mines which block is determined by the previous block hash, so occasional runs of one miner doing many blocks in a row is to be expected.
+
+When --multiminer is used, if a miner is down and does not mine a block within five minutes of when it is due, the other miners will automatically act as redundant backups ensuring the chain does not halt. The --backup-delay parameter can be used to change how long a given miner waits, allowing one to be the primary backup (after five minutes) and another to be the secondary backup (after six minutes, eg).
+
+The --standby-delay parameter can be used to make a backup miner that only mines if a block doesn't arrive on time. This can be combined with --multiminer if desired. Setting --standby-delay also prevents the first block from being mined immediately.
+
+Advanced usage
+--------------
+
+The process generate follows internally is to get a block template, convert that into a PSBT, sign the PSBT, move the signature from the signed PSBT into the block template's coinbase, grind proof of work for the block, and then submit the block to the network.
+
+These steps can instead be done explicitly:
+
+    $CLI -signet getblocktemplate '{"rules": ["signet","segwit"]}' |
+      $MINER --cli="$CLI" genpsbt --address="$ADDR" |
+      $CLI -signet -stdin walletprocesspsbt |
+      jq -r .psbt |
+      $MINER --cli="$CLI" solvepsbt --grind-cmd="$GRIND" |
+      $CLI -signet -stdin submitblock
+
+This is intended to allow you to replace part of the pipeline for further experimentation (eg, to sign the block with a hardware wallet).
+

contrib/signet/getcoins.py

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+#!/usr/bin/env python3
+# Copyright (c) 2020 The DigiByte Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+import argparse
+import subprocess
+import requests
+import sys
+
+parser = argparse.ArgumentParser(description='Script to get coins from a faucet.', epilog='You may need to start with double-dash (--) when providing digibyte-cli arguments.')
+parser.add_argument('-c', '--cmd', dest='cmd', default='digibyte-cli', help='digibyte-cli command to use')
+parser.add_argument('-f', '--faucet', dest='faucet', default='https://signetfaucet.com/claim', help='URL of the faucet')
+parser.add_argument('-a', '--addr', dest='addr', default='', help='DigiByte address to which the faucet should send')
+parser.add_argument('-p', '--password', dest='password', default='', help='Faucet password, if any')
+parser.add_argument('digibyte_cli_args', nargs='*', help='Arguments to pass on to digibyte-cli (default: -signet)')
+
+args = parser.parse_args()
+
+if args.addr == '':
+    if args.digibyte_cli_args == []:
+        args.digibyte_cli_args = ['-signet']
+    # get address for receiving coins
+    try:
+        args.addr = subprocess.check_output([args.cmd] + args.digibyte_cli_args + ['getnewaddress', 'faucet', 'bech32']).strip()
+    except FileNotFoundError:
+        print('The binary', args.cmd, 'could not be found.')
+        exit()
+
+data = {'address': args.addr, 'password': args.password}
+try:
+    res = requests.post(args.faucet, data=data)
+except:
+    print('Unexpected error when contacting faucet:', sys.exc_info()[0])
+    exit()
+print(res.text)

contrib/signet/miner

@@ -0,0 +1,631 @@
+#!/usr/bin/env python3
+# Copyright (c) 2020 The DigiByte Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+import argparse
+import base64
+import json
+import logging
+import math
+import os.path
+import re
+import struct
+import sys
+import time
+import subprocess
+
+from binascii import unhexlify
+from io import BytesIO
+
+PATH_BASE_CONTRIB_SIGNET = os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+PATH_BASE_TEST_FUNCTIONAL = os.path.abspath(os.path.join(PATH_BASE_CONTRIB_SIGNET, "..", "..", "test", "functional"))
+sys.path.insert(0, PATH_BASE_TEST_FUNCTIONAL)
+
+from test_framework.blocktools import WITNESS_COMMITMENT_HEADER, script_BIP34_coinbase_height # noqa: E402
+from test_framework.messages import CBlock, CBlockHeader, COutPoint, CTransaction, CTxIn, CTxInWitness, CTxOut, from_hex, deser_string, hash256, ser_compact_size, ser_string, ser_uint256, tx_from_hex, uint256_from_str # noqa: E402
+from test_framework.script import CScriptOp # noqa: E402
+
+logging.basicConfig(
+    format='%(asctime)s %(levelname)s %(message)s',
+    level=logging.INFO,
+    datefmt='%Y-%m-%d %H:%M:%S')
+
+SIGNET_HEADER = b"\xec\xc7\xda\xa2"
+PSBT_SIGNET_BLOCK = b"\xfc\x06signetb"    # proprietary PSBT global field holding the block being signed
+RE_MULTIMINER = re.compile("^(\d+)(-(\d+))?/(\d+)$")
+
+# #### some helpers that could go into test_framework
+
+# like from_hex, but without the hex part
+def FromBinary(cls, stream):
+    """deserialize a binary stream (or bytes object) into an object"""
+    # handle bytes object by turning it into a stream
+    was_bytes = isinstance(stream, bytes)
+    if was_bytes:
+        stream = BytesIO(stream)
+    obj = cls()
+    obj.deserialize(stream)
+    if was_bytes:
+        assert len(stream.read()) == 0
+    return obj
+
+class PSBTMap:
+    """Class for serializing and deserializing PSBT maps"""
+
+    def __init__(self, map=None):
+        self.map = map if map is not None else {}
+
+    def deserialize(self, f):
+        m = {}
+        while True:
+            k = deser_string(f)
+            if len(k) == 0:
+                break
+            v = deser_string(f)
+            if len(k) == 1:
+                k = k[0]
+            assert k not in m
+            m[k] = v
+        self.map = m
+
+    def serialize(self):
+        m = b""
+        for k,v in self.map.items():
+            if isinstance(k, int) and 0 <= k and k <= 255:
+                k = bytes([k])
+            m += ser_compact_size(len(k)) + k
+            m += ser_compact_size(len(v)) + v
+        m += b"\x00"
+        return m
+
+class PSBT:
+    """Class for serializing and deserializing PSBTs"""
+
+    def __init__(self):
+        self.g = PSBTMap()
+        self.i = []
+        self.o = []
+        self.tx = None
+
+    def deserialize(self, f):
+        assert f.read(5) == b"psbt\xff"
+        self.g = FromBinary(PSBTMap, f)
+        assert 0 in self.g.map
+        self.tx = FromBinary(CTransaction, self.g.map[0])
+        self.i = [FromBinary(PSBTMap, f) for _ in self.tx.vin]
+        self.o = [FromBinary(PSBTMap, f) for _ in self.tx.vout]
+        return self
+
+    def serialize(self):
+        assert isinstance(self.g, PSBTMap)
+        assert isinstance(self.i, list) and all(isinstance(x, PSBTMap) for x in self.i)
+        assert isinstance(self.o, list) and all(isinstance(x, PSBTMap) for x in self.o)
+        assert 0 in self.g.map
+        tx = FromBinary(CTransaction, self.g.map[0])
+        assert len(tx.vin) == len(self.i)
+        assert len(tx.vout) == len(self.o)
+
+        psbt = [x.serialize() for x in [self.g] + self.i + self.o]
+        return b"psbt\xff" + b"".join(psbt)
+
+    def to_base64(self):
+        return base64.b64encode(self.serialize()).decode("utf8")
+
+    @classmethod
+    def from_base64(cls, b64psbt):
+        return FromBinary(cls, base64.b64decode(b64psbt))
+
+# #####
+
+def create_coinbase(height, value, spk):
+    cb = CTransaction()
+    cb.vin = [CTxIn(COutPoint(0, 0xffffffff), script_BIP34_coinbase_height(height), 0xffffffff)]
+    cb.vout = [CTxOut(value, spk)]
+    return cb
+
+def get_witness_script(witness_root, witness_nonce):
+    commitment = uint256_from_str(hash256(ser_uint256(witness_root) + ser_uint256(witness_nonce)))
+    return b"\x6a" + CScriptOp.encode_op_pushdata(WITNESS_COMMITMENT_HEADER + ser_uint256(commitment))
+
+def signet_txs(block, challenge):
+    # assumes signet solution has not been added yet so does not need
+    # to be removed
+
+    txs = block.vtx[:]
+    txs[0] = CTransaction(txs[0])
+    txs[0].vout[-1].scriptPubKey += CScriptOp.encode_op_pushdata(SIGNET_HEADER)
+    hashes = []
+    for tx in txs:
+        tx.rehash()
+        hashes.append(ser_uint256(tx.sha256))
+    mroot = block.get_merkle_root(hashes)
+
+    sd = b""
+    sd += struct.pack("<i", block.nVersion)
+    sd += ser_uint256(block.hashPrevBlock)
+    sd += ser_uint256(mroot)
+    sd += struct.pack("<I", block.nTime)
+
+    to_spend = CTransaction()
+    to_spend.nVersion = 0
+    to_spend.nLockTime = 0
+    to_spend.vin = [CTxIn(COutPoint(0, 0xFFFFFFFF), b"\x00" + CScriptOp.encode_op_pushdata(sd), 0)]
+    to_spend.vout = [CTxOut(0, challenge)]
+    to_spend.rehash()
+
+    spend = CTransaction()
+    spend.nVersion = 0
+    spend.nLockTime = 0
+    spend.vin = [CTxIn(COutPoint(to_spend.sha256, 0), b"", 0)]
+    spend.vout = [CTxOut(0, b"\x6a")]
+
+    return spend, to_spend
+
+def do_createpsbt(block, signme, spendme):
+    psbt = PSBT()
+    psbt.g = PSBTMap( {0: signme.serialize(),
+                       PSBT_SIGNET_BLOCK: block.serialize()
+                     } )
+    psbt.i = [ PSBTMap( {0: spendme.serialize(),
+                         3: bytes([1,0,0,0])})
+             ]
+    psbt.o = [ PSBTMap() ]
+    return psbt.to_base64()
+
+def do_decode_psbt(b64psbt):
+    psbt = PSBT.from_base64(b64psbt)
+
+    assert len(psbt.tx.vin) == 1
+    assert len(psbt.tx.vout) == 1
+    assert PSBT_SIGNET_BLOCK in psbt.g.map
+
+    scriptSig = psbt.i[0].map.get(7, b"")
+    scriptWitness = psbt.i[0].map.get(8, b"\x00")
+
+    return FromBinary(CBlock, psbt.g.map[PSBT_SIGNET_BLOCK]), ser_string(scriptSig) + scriptWitness
+
+def finish_block(block, signet_solution, grind_cmd):
+    block.vtx[0].vout[-1].scriptPubKey += CScriptOp.encode_op_pushdata(SIGNET_HEADER + signet_solution)
+    block.vtx[0].rehash()
+    block.hashMerkleRoot = block.calc_merkle_root()
+    if grind_cmd is None:
+        block.solve()
+    else:
+        headhex = CBlockHeader.serialize(block).hex()
+        cmd = grind_cmd.split(" ") + [headhex]
+        newheadhex = subprocess.run(cmd, stdout=subprocess.PIPE, input=b"", check=True).stdout.strip()
+        newhead = from_hex(CBlockHeader(), newheadhex.decode('utf8'))
+        block.nNonce = newhead.nNonce
+        block.rehash()
+    return block
+
+def generate_psbt(tmpl, reward_spk, *, blocktime=None):
+    signet_spk = tmpl["signet_challenge"]
+    signet_spk_bin = unhexlify(signet_spk)
+
+    cbtx = create_coinbase(height=tmpl["height"], value=tmpl["coinbasevalue"], spk=reward_spk)
+    cbtx.vin[0].nSequence = 2**32-2
+    cbtx.rehash()
+
+    block = CBlock()
+    block.nVersion = tmpl["version"]
+    block.hashPrevBlock = int(tmpl["previousblockhash"], 16)
+    block.nTime = tmpl["curtime"] if blocktime is None else blocktime
+    if block.nTime < tmpl["mintime"]:
+        block.nTime = tmpl["mintime"]
+    block.nBits = int(tmpl["bits"], 16)
+    block.nNonce = 0
+    block.vtx = [cbtx] + [tx_from_hex(t["data"]) for t in tmpl["transactions"]]
+
+    witnonce = 0
+    witroot = block.calc_witness_merkle_root()
+    cbwit = CTxInWitness()
+    cbwit.scriptWitness.stack = [ser_uint256(witnonce)]
+    block.vtx[0].wit.vtxinwit = [cbwit]
+    block.vtx[0].vout.append(CTxOut(0, get_witness_script(witroot, witnonce)))
+
+    signme, spendme = signet_txs(block, signet_spk_bin)
+
+    return do_createpsbt(block, signme, spendme)
+
+def get_reward_address(args, height):
+    if args.address is not None:
+        return args.address
+
+    if '*' not in args.descriptor:
+        addr = json.loads(args.bcli("deriveaddresses", args.descriptor))[0]
+        args.address = addr
+        return addr
+
+    remove = [k for k in args.derived_addresses.keys() if k+20 <= height]
+    for k in remove:
+        del args.derived_addresses[k]
+
+    addr = args.derived_addresses.get(height, None)
+    if addr is None:
+        addrs = json.loads(args.bcli("deriveaddresses", args.descriptor, "[%d,%d]" % (height, height+20)))
+        addr = addrs[0]
+        for k, a in enumerate(addrs):
+            args.derived_addresses[height+k] = a
+
+    return addr
+
+def get_reward_addr_spk(args, height):
+    assert args.address is not None or args.descriptor is not None
+
+    if hasattr(args, "reward_spk"):
+        return args.address, args.reward_spk
+
+    reward_addr = get_reward_address(args, height)
+    reward_spk = unhexlify(json.loads(args.bcli("getaddressinfo", reward_addr))["scriptPubKey"])
+    if args.address is not None:
+        # will always be the same, so cache
+        args.reward_spk = reward_spk
+
+    return reward_addr, reward_spk
+
+def do_genpsbt(args):
+    tmpl = json.load(sys.stdin)
+    _, reward_spk = get_reward_addr_spk(args, tmpl["height"])
+    psbt = generate_psbt(tmpl, reward_spk)
+    print(psbt)
+
+def do_solvepsbt(args):
+    block, signet_solution = do_decode_psbt(sys.stdin.read())
+    block = finish_block(block, signet_solution, args.grind_cmd)
+    print(block.serialize().hex())
+
+def nbits_to_target(nbits):
+    shift = (nbits >> 24) & 0xff
+    return (nbits & 0x00ffffff) * 2**(8*(shift - 3))
+
+def target_to_nbits(target):
+    tstr = "{0:x}".format(target)
+    if len(tstr) < 6:
+        tstr = ("000000"+tstr)[-6:]
+    if len(tstr) % 2 != 0:
+        tstr = "0" + tstr
+    if int(tstr[0],16) >= 0x8:
+        # avoid "negative"
+        tstr = "00" + tstr
+    fix = int(tstr[:6], 16)
+    sz = len(tstr)//2
+    if tstr[6:] != "0"*(sz*2-6):
+        fix += 1
+
+    return int("%02x%06x" % (sz,fix), 16)
+
+def seconds_to_hms(s):
+    if s == 0:
+        return "0s"
+    neg = (s < 0)
+    if neg:
+        s = -s
+    out = ""
+    if s % 60 > 0:
+        out = "%ds" % (s % 60)
+    s //= 60
+    if s % 60 > 0:
+        out = "%dm%s" % (s % 60, out)
+    s //= 60
+    if s > 0:
+        out = "%dh%s" % (s, out)
+    if neg:
+        out = "-" + out
+    return out
+
+def next_block_delta(last_nbits, last_hash, ultimate_target, do_poisson):
+    # strategy:
+    #  1) work out how far off our desired target we are
+    #  2) cap it to a factor of 4 since that's the best we can do in a single retarget period
+    #  3) use that to work out the desired average interval in this retarget period
+    #  4) if doing poisson, use the last hash to pick a uniformly random number in [0,1), and work out a random multiplier to vary the average by
+    #  5) cap the resulting interval between 1 second and 1 hour to avoid extremes
+
+    INTERVAL = 600.0*2016/2015 # 10 minutes, adjusted for the off-by-one bug
+
+    current_target = nbits_to_target(last_nbits)
+    retarget_factor = ultimate_target / current_target
+    retarget_factor = max(0.25, min(retarget_factor, 4.0))
+
+    avg_interval = INTERVAL * retarget_factor
+
+    if do_poisson:
+        det_rand = int(last_hash[-8:], 16) * 2**-32
+        this_interval_variance = -math.log1p(-det_rand)
+    else:
+        this_interval_variance = 1
+
+    this_interval = avg_interval * this_interval_variance
+    this_interval = max(1, min(this_interval, 3600))
+
+    return this_interval
+
+def next_block_is_mine(last_hash, my_blocks):
+    det_rand = int(last_hash[-16:-8], 16)
+    return my_blocks[0] <= (det_rand % my_blocks[2]) < my_blocks[1]
+
+def do_generate(args):
+    if args.max_blocks is not None:
+        if args.ongoing:
+            logging.error("Cannot specify both --ongoing and --max-blocks")
+            return 1
+        if args.max_blocks < 1:
+            logging.error("N must be a positive integer")
+            return 1
+        max_blocks = args.max_blocks
+    elif args.ongoing:
+        max_blocks = None
+    else:
+        max_blocks = 1
+
+    if args.set_block_time is not None and max_blocks != 1:
+        logging.error("Cannot specify --ongoing or --max-blocks > 1 when using --set-block-time")
+        return 1
+    if args.set_block_time is not None and args.set_block_time < 0:
+        args.set_block_time = time.time()
+        logging.info("Treating negative block time as current time (%d)" % (args.set_block_time))
+
+    if args.min_nbits:
+        if args.nbits is not None:
+            logging.error("Cannot specify --nbits and --min-nbits")
+            return 1
+        args.nbits = "1e0377ae"
+        logging.info("Using nbits=%s" % (args.nbits))
+
+    if args.set_block_time is None:
+        if args.nbits is None or len(args.nbits) != 8:
+            logging.error("Must specify --nbits (use calibrate command to determine value)")
+            return 1
+
+    if args.multiminer is None:
+       my_blocks = (0,1,1)
+    else:
+        if not args.ongoing:
+            logging.error("Cannot specify --multiminer without --ongoing")
+            return 1
+        m = RE_MULTIMINER.match(args.multiminer)
+        if m is None:
+            logging.error("--multiminer argument must be k/m or j-k/m")
+            return 1
+        start,_,stop,total = m.groups()
+        if stop is None:
+            stop = start
+        start, stop, total = map(int, (start, stop, total))
+        if stop < start or start <= 0 or total < stop or total == 0:
+            logging.error("Inconsistent values for --multiminer")
+            return 1
+        my_blocks = (start-1, stop, total)
+
+    ultimate_target = nbits_to_target(int(args.nbits,16))
+
+    mined_blocks = 0
+    bestheader = {"hash": None}
+    lastheader = None
+    while max_blocks is None or mined_blocks < max_blocks:
+
+        # current status?
+        bci = json.loads(args.bcli("getblockchaininfo"))
+
+        if bestheader["hash"] != bci["bestblockhash"]:
+            bestheader = json.loads(args.bcli("getblockheader", bci["bestblockhash"]))
+
+        if lastheader is None:
+            lastheader = bestheader["hash"]
+        elif bestheader["hash"] != lastheader:
+            next_delta = next_block_delta(int(bestheader["bits"], 16), bestheader["hash"], ultimate_target, args.poisson)
+            next_delta += bestheader["time"] - time.time()
+            next_is_mine = next_block_is_mine(bestheader["hash"], my_blocks)
+            logging.info("Received new block at height %d; next in %s (%s)", bestheader["height"], seconds_to_hms(next_delta), ("mine" if next_is_mine else "backup"))
+            lastheader = bestheader["hash"]
+
+        # when is the next block due to be mined?
+        now = time.time()
+        if args.set_block_time is not None:
+            logging.debug("Setting start time to %d", args.set_block_time)
+            mine_time = args.set_block_time
+            action_time = now
+            is_mine = True
+        elif bestheader["height"] == 0:
+            time_delta = next_block_delta(int(bestheader["bits"], 16), bci["bestblockhash"], ultimate_target, args.poisson)
+            time_delta *= 100 # 100 blocks
+            logging.info("Backdating time for first block to %d minutes ago" % (time_delta/60))
+            mine_time = now - time_delta
+            action_time = now
+            is_mine = True
+        else:
+            time_delta = next_block_delta(int(bestheader["bits"], 16), bci["bestblockhash"], ultimate_target, args.poisson)
+            mine_time = bestheader["time"] + time_delta
+
+            is_mine = next_block_is_mine(bci["bestblockhash"], my_blocks)
+
+            action_time = mine_time
+            if not is_mine:
+                action_time += args.backup_delay
+
+            if args.standby_delay > 0:
+                action_time += args.standby_delay
+            elif mined_blocks == 0:
+                # for non-standby, always mine immediately on startup,
+                # even if the next block shouldn't be ours
+                action_time = now
+
+        # don't want fractional times so round down
+        mine_time = int(mine_time)
+        action_time = int(action_time)
+
+        # can't mine a block 2h in the future; 1h55m for some safety
+        action_time = max(action_time, mine_time - 6900)
+
+        # ready to go? otherwise sleep and check for new block
+        if now < action_time:
+            sleep_for = min(action_time - now, 60)
+            if mine_time < now:
+                # someone else might have mined the block,
+                # so check frequently, so we don't end up late
+                # mining the next block if it's ours
+                sleep_for = min(20, sleep_for)
+            minestr = "mine" if is_mine else "backup"
+            logging.debug("Sleeping for %s, next block due in %s (%s)" % (seconds_to_hms(sleep_for), seconds_to_hms(mine_time - now), minestr))
+            time.sleep(sleep_for)
+            continue
+
+        # gbt
+        tmpl = json.loads(args.bcli("getblocktemplate", '{"rules":["signet","segwit"]}'))
+        if tmpl["previousblockhash"] != bci["bestblockhash"]:
+            logging.warning("GBT based off unexpected block (%s not %s), retrying", tmpl["previousblockhash"], bci["bestblockhash"])
+            time.sleep(1)
+            continue
+
+        logging.debug("GBT template: %s", tmpl)
+
+        if tmpl["mintime"] > mine_time:
+            logging.info("Updating block time from %d to %d", mine_time, tmpl["mintime"])
+            mine_time = tmpl["mintime"]
+            if mine_time > now:
+                logging.error("GBT mintime is in the future: %d is %d seconds later than %d", mine_time, (mine_time-now), now)
+                return 1
+
+        # address for reward
+        reward_addr, reward_spk = get_reward_addr_spk(args, tmpl["height"])
+
+        # mine block
+        logging.debug("Mining block delta=%s start=%s mine=%s", seconds_to_hms(mine_time-bestheader["time"]), mine_time, is_mine)
+        mined_blocks += 1
+        psbt = generate_psbt(tmpl, reward_spk, blocktime=mine_time)
+        psbt_signed = json.loads(args.bcli("-stdin", "walletprocesspsbt", input=psbt.encode('utf8')))
+        if not psbt_signed.get("complete",False):
+            logging.debug("Generated PSBT: %s" % (psbt,))
+            sys.stderr.write("PSBT signing failed")
+            return 1
+        block, signet_solution = do_decode_psbt(psbt_signed["psbt"])
+        block = finish_block(block, signet_solution, args.grind_cmd)
+
+        # submit block
+        r = args.bcli("-stdin", "submitblock", input=block.serialize().hex().encode('utf8'))
+
+        # report
+        bstr = "block" if is_mine else "backup block"
+
+        next_delta = next_block_delta(block.nBits, block.hash, ultimate_target, args.poisson)
+        next_delta += block.nTime - time.time()
+        next_is_mine = next_block_is_mine(block.hash, my_blocks)
+
+        logging.debug("Block hash %s payout to %s", block.hash, reward_addr)
+        logging.info("Mined %s at height %d; next in %s (%s)", bstr, tmpl["height"], seconds_to_hms(next_delta), ("mine" if next_is_mine else "backup"))
+        if r != "":
+            logging.warning("submitblock returned %s for height %d hash %s", r, tmpl["height"], block.hash)
+        lastheader = block.hash
+
+def do_calibrate(args):
+    if args.nbits is not None and args.seconds is not None:
+        sys.stderr.write("Can only specify one of --nbits or --seconds\n")
+        return 1
+    if args.nbits is not None and len(args.nbits) != 8:
+        sys.stderr.write("Must specify 8 hex digits for --nbits\n")
+        return 1
+
+    TRIALS = 600 # gets variance down pretty low
+    TRIAL_BITS = 0x1e3ea75f # takes about 5m to do 600 trials
+
+    header = CBlockHeader()
+    header.nBits = TRIAL_BITS
+    targ = nbits_to_target(header.nBits)
+
+    start = time.time()
+    count = 0
+    for i in range(TRIALS):
+        header.nTime = i
+        header.nNonce = 0
+        headhex = header.serialize().hex()
+        cmd = args.grind_cmd.split(" ") + [headhex]
+        newheadhex = subprocess.run(cmd, stdout=subprocess.PIPE, input=b"", check=True).stdout.strip()
+
+    avg = (time.time() - start) * 1.0 / TRIALS
+
+    if args.nbits is not None:
+        want_targ = nbits_to_target(int(args.nbits,16))
+        want_time = avg*targ/want_targ
+    else:
+        want_time = args.seconds if args.seconds is not None else 25
+        want_targ = int(targ*(avg/want_time))
+
+    print("nbits=%08x for %ds average mining time" % (target_to_nbits(want_targ), want_time))
+    return 0
+
+def digibyte_cli(basecmd, args, **kwargs):
+    cmd = basecmd + ["-signet"] + args
+    logging.debug("Calling digibyte-cli: %r", cmd)
+    out = subprocess.run(cmd, stdout=subprocess.PIPE, **kwargs, check=True).stdout
+    if isinstance(out, bytes):
+        out = out.decode('utf8')
+    return out.strip()
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--cli", default="digibyte-cli", type=str, help="digibyte-cli command")
+    parser.add_argument("--debug", action="store_true", help="Print debugging info")
+    parser.add_argument("--quiet", action="store_true", help="Only print warnings/errors")
+
+    cmds = parser.add_subparsers(help="sub-commands")
+    genpsbt = cmds.add_parser("genpsbt", help="Generate a block PSBT for signing")
+    genpsbt.set_defaults(fn=do_genpsbt)
+
+    solvepsbt = cmds.add_parser("solvepsbt", help="Solve a signed block PSBT")
+    solvepsbt.set_defaults(fn=do_solvepsbt)
+
+    generate = cmds.add_parser("generate", help="Mine blocks")
+    generate.set_defaults(fn=do_generate)
+    generate.add_argument("--ongoing", action="store_true", help="Keep mining blocks")
+    generate.add_argument("--max-blocks", default=None, type=int, help="Max blocks to mine (default=1)")
+    generate.add_argument("--set-block-time", default=None, type=int, help="Set block time (unix timestamp)")
+    generate.add_argument("--nbits", default=None, type=str, help="Target nBits (specify difficulty)")
+    generate.add_argument("--min-nbits", action="store_true", help="Target minimum nBits (use min difficulty)")
+    generate.add_argument("--poisson", action="store_true", help="Simulate randomised block times")
+    generate.add_argument("--multiminer", default=None, type=str, help="Specify which set of blocks to mine (eg: 1-40/100 for the first 40%%, 2/3 for the second 3rd)")
+    generate.add_argument("--backup-delay", default=300, type=int, help="Seconds to delay before mining blocks reserved for other miners (default=300)")
+    generate.add_argument("--standby-delay", default=0, type=int, help="Seconds to delay before mining blocks (default=0)")
+
+    calibrate = cmds.add_parser("calibrate", help="Calibrate difficulty")
+    calibrate.set_defaults(fn=do_calibrate)
+    calibrate.add_argument("--nbits", type=str, default=None)
+    calibrate.add_argument("--seconds", type=int, default=None)
+
+    for sp in [genpsbt, generate]:
+        sp.add_argument("--address", default=None, type=str, help="Address for block reward payment")
+        sp.add_argument("--descriptor", default=None, type=str, help="Descriptor for block reward payment")
+
+    for sp in [solvepsbt, generate, calibrate]:
+        sp.add_argument("--grind-cmd", default=None, type=str, required=(sp==calibrate), help="Command to grind a block header for proof-of-work")
+
+    args = parser.parse_args(sys.argv[1:])
+
+    args.bcli = lambda *a, input=b"", **kwargs: digibyte_cli(args.cli.split(" "), list(a), input=input, **kwargs)
+
+    if hasattr(args, "address") and hasattr(args, "descriptor"):
+        if args.address is None and args.descriptor is None:
+            sys.stderr.write("Must specify --address or --descriptor\n")
+            return 1
+        elif args.address is not None and args.descriptor is not None:
+            sys.stderr.write("Only specify one of --address or --descriptor\n")
+            return 1
+        args.derived_addresses = {}
+
+    if args.debug:
+        logging.getLogger().setLevel(logging.DEBUG)
+    elif args.quiet:
+        logging.getLogger().setLevel(logging.WARNING)
+    else:
+        logging.getLogger().setLevel(logging.INFO)
+
+    if hasattr(args, "fn"):
+        return args.fn(args)
+    else:
+        logging.error("Must specify command")
+        return 1
+
+if __name__ == "__main__":
+    main()
+
+