Example #1
0
async def set_highwater(*a):
    # rarely? used command
    import callgate

    have = version.get_mpy_version()[0]
    ts = version.get_header_value('timestamp')

    hw = callgate.get_highwater()

    if hw == ts:
        await ux_show_story(
            '''Current version (%s) already marked as high-water mark.''' %
            have)
        return

    ok = await ux_confirm(
        '''Mark current version (%s) as the minimum, and prevent any downgrades below this version.

Rarely needed as critical security updates will set this automatically.''' %
        have)

    if not ok: return

    rv = callgate.set_highwater(ts)

    # add error display here? meh.

    assert rv == 0, "Failed: %r" % rv
Example #2
0
async def show_version(*a):
    # show firmware, bootload versions.
    from main import settings
    import callgate, version
    from ubinascii import hexlify as b2a_hex

    built, rel, *_ = version.get_mpy_version()
    bl = callgate.get_bl_version()[0]
    chk = str(b2a_hex(callgate.get_bl_checksum(0))[-8:], 'ascii')

    msg = '''\
Coldcard Firmware

  {rel}
  {built}


Bootloader:
  {bl}
  {chk}

Serial:
  {ser}

Hardware:
  {hw}
'''

    await ux_show_story(
        msg.format(rel=rel,
                   built=built,
                   bl=bl,
                   chk=chk,
                   ser=version.serial_number(),
                   hw=version.hw_label))
Example #3
0
    def splash(self):
        # display a splash screen with some version numbers
        self.clear()
        y = 4
        self.text(None,    y, 'Coldcard', font=FontLarge)
        self.text(None, y+20, 'Wallet', font=FontLarge)

        from version import get_mpy_version
        timestamp, label, *_ = get_mpy_version()

        y = self.HEIGHT-10
        self.text(0,  y, 'Version '+label, font=FontTiny)
        self.text(-1, y, timestamp, font=FontTiny)
        
        self.show()
Example #4
0
def generate_bitcoin_core_wallet(example_addrs, account_num):
    # Generate the data for an RPC command to import keys into Bitcoin Core
    # - yields dicts for json purposes
    from descriptor import append_checksum
    from main import settings
    import ustruct

    from public_constants import AF_P2WPKH

    chain = chains.current_chain()

    derive = "84'/{coin_type}'/{account}'".format(account=account_num,
                                                  coin_type=chain.b44_cointype)

    with stash.SensitiveValues() as sv:
        prefix = sv.derive_path(derive)
        xpub = chain.serialize_public(prefix)

        for i in range(3):
            sp = '0/%d' % i
            node = sv.derive_path(sp, master=prefix)
            a = chain.address(node, AF_P2WPKH)
            example_addrs.append(('m/%s/%s' % (derive, sp), a))

    xfp = settings.get('xfp')
    txt_xfp = xfp2str(xfp).lower()

    chain = chains.current_chain()

    _, vers, _ = version.get_mpy_version()

    for internal in [False, True]:
        desc = "wpkh([{fingerprint}/{derive}]{xpub}/{change}/*)".format(
            derive=derive.replace("'", "h"),
            fingerprint=txt_xfp,
            coin_type=chain.b44_cointype,
            account=0,
            xpub=xpub,
            change=(1 if internal else 0))

        yield {
            'desc': append_checksum(desc),
            'range': [0, 1000],
            'timestamp': 'now',
            'internal': internal,
            'keypool': True,
            'watchonly': True
        }
Example #5
0
def generate_wasabi_wallet():
    # Generate the data for a JSON file which Wasabi can open directly as a new wallet.
    import ustruct, version

    # bitcoin (xpub) is used, even for testnet case (ie. no tpub)
    # - altho, doesn't matter; the wallet operates based on it's own settings for test/mainnet
    #   regardless of the contents of the wallet file
    btc = chains.BitcoinMain

    with stash.SensitiveValues() as sv:
        xpub = btc.serialize_public(sv.derive_path("84'/0'/0'"))

    xfp = settings.get('xfp')
    txt_xfp = xfp2str(xfp)

    chain = chains.current_chain()
    assert chain.ctype in {'BTC', 'XTN'}, "Only Bitcoin supported"

    _,vers,_ = version.get_mpy_version()

    return dict(MasterFingerprint=txt_xfp,
                ColdCardFirmwareVersion=vers,
                ExtPubKey=xpub)
Example #6
0
def render_backup_contents():
    # simple text format:
    #   key = value
    # or #comments
    # but value is JSON
    from main import settings, pa

    rv = StringIO()

    def COMMENT(val=None):
        if val:
            rv.write('\n# %s\n' % val)
        else:
            rv.write('\n')

    def ADD(key, val):
        rv.write('%s = %s\n' % (key, ujson.dumps(val)))

    rv.write('# Coldcard backup file! DO NOT CHANGE.\n')

    chain = chains.current_chain()

    COMMENT('Private key details: ' + chain.name)

    with stash.SensitiveValues(for_backup=True) as sv:

        if sv.mode == 'words':
            ADD('mnemonic', tcc.bip39.from_data(sv.raw))

        if sv.mode == 'master':
            ADD('bip32_master_key', b2a_hex(sv.raw))

        ADD('chain', chain.ctype)
        ADD('xprv', chain.serialize_private(sv.node))
        ADD('xpub', chain.serialize_public(sv.node))

        # BTW: everything is really a duplicate of this value
        ADD('raw_secret', b2a_hex(sv.secret).rstrip(b'0'))

        if pa.has_duress_pin():
            COMMENT('Duress Wallet (informational)')
            dpk = sv.duress_root()
            ADD('duress_xprv', chain.serialize_private(dpk))
            ADD('duress_xpub', chain.serialize_public(dpk))

        if version.has_608:
            # save the so-called long-secret
            ADD('long_secret', b2a_hex(pa.ls_fetch()))

    COMMENT('Firmware version (informational)')
    date, vers, timestamp = version.get_mpy_version()[0:3]
    ADD('fw_date', date)
    ADD('fw_version', vers)
    ADD('fw_timestamp', timestamp)
    ADD('serial', version.serial_number())

    COMMENT('User preferences')

    # user preferences
    for k, v in settings.current.items():
        if k[0] == '_': continue  # debug stuff in simulator
        if k == 'xpub': continue  # redundant, and wrong if bip39pw
        if k == 'xfp': continue  # redundant, and wrong if bip39pw
        ADD('setting.' + k, v)

    if version.has_fatram:
        import hsm
        if hsm.hsm_policy_available():
            ADD('hsm_policy', hsm.capture_backup())

    rv.write('\n# EOF\n')

    return rv.getvalue()
Example #7
0
    async def handle(self, cmd, args):
        # Dispatch incoming message, and provide reply.
        from main import hsm_active, is_devmode

        try:
            cmd = bytes(cmd).decode()
        except:
            raise FramingError('decode')

        if cmd[0].isupper() and (is_simulator() or is_devmode):
            # special hacky commands to support testing w/ the simulator
            try:
                from usb_test_commands import do_usb_command
                return do_usb_command(cmd, args)
            except:
                raise
                pass

        if hsm_active:
            # only a few commands are allowed during HSM mode
            if cmd not in HSM_WHITELIST:
                raise HSMDenied

        if cmd == 'dfu_':
            # only useful in factory, undocumented.
            return self.call_after(callgate.enter_dfu)

        if cmd == 'rebo':
            import machine
            return self.call_after(machine.reset)

        if cmd == 'logo':
            from utils import clean_shutdown
            return self.call_after(clean_shutdown)

        if cmd == 'ping':
            return b'biny' + args

        if cmd == 'upld':
            offset, total_size = unpack_from('<II', args)
            data = memoryview(args)[4 + 4:]

            return await self.handle_upload(offset, total_size, data)

        if cmd == 'dwld':
            offset, length, fileno = unpack_from('<III', args)
            return await self.handle_download(offset, length, fileno)

        if cmd == 'ncry':
            version, his_pubkey = unpack_from('<I64s', args)

            return self.handle_crypto_setup(version, his_pubkey)

        if cmd == 'vers':
            from version import get_mpy_version, hw_label
            from callgate import get_bl_version

            # Returning: date, version(human), bootloader version, full date version
            # BUT: be ready for additions!
            rv = list(get_mpy_version())
            rv.insert(2, get_bl_version()[0])
            rv.append(hw_label)

            return b'asci' + ('\n'.join(rv)).encode()

        if cmd == 'sha2':
            return b'biny' + self.file_checksum.digest()

        if cmd == 'xpub':
            assert self.encrypted_req, 'must encrypt'
            return self.handle_xpub(args)

        if cmd == 'mitm':
            assert self.encrypted_req, 'must encrypt'
            return await self.handle_mitm_check()

        if cmd == 'smsg':
            # sign message
            addr_fmt, len_subpath, len_msg = unpack_from('<III', args)
            subpath = args[12:12 + len_subpath]
            msg = args[12 + len_subpath:]
            assert len(msg) == len_msg, "badlen"

            from auth import sign_msg
            sign_msg(msg, subpath, addr_fmt)
            return None

        if cmd == 'p2sh':
            # show P2SH (probably multisig) address on screen (also provides it back)
            # - must provide redeem script, and list of [xfp+path]
            from auth import start_show_p2sh_address

            if hsm_active and not hsm_active.approve_address_share(
                    is_p2sh=True):
                raise HSMDenied

            # new multsig goodness, needs mapping from xfp->path and M values
            addr_fmt, M, N, script_len = unpack_from('<IBBH', args)

            assert addr_fmt & AFC_SCRIPT
            assert 1 <= M <= N <= 20
            assert 30 <= script_len <= 520

            offset = 8
            witdeem_script = args[offset:offset + script_len]
            offset += script_len

            assert len(witdeem_script) == script_len

            xfp_paths = []
            for i in range(N):
                ln = args[offset]
                assert 1 <= ln <= 16, 'badlen'
                xfp_paths.append(unpack_from('<%dI' % ln, args, offset + 1))
                offset += (ln * 4) + 1

            assert offset == len(args)

            return b'asci' + start_show_p2sh_address(M, N, addr_fmt, xfp_paths,
                                                     witdeem_script)

        if cmd == 'show':
            # simple cases, older code: text subpath
            from auth import start_show_address

            addr_fmt, = unpack_from('<I', args)
            assert not (addr_fmt & AFC_SCRIPT)

            return b'asci' + start_show_address(addr_fmt, subpath=args[4:])

        if cmd == 'enrl':
            # Enroll new xpubkey to be involved in multisigs.
            # - text config file must already be uploaded

            file_len, file_sha = unpack_from('<I32s', args)
            if file_sha != self.file_checksum.digest():
                return b'err_Checksum'
            assert 100 < file_len <= (20 * 200), "badlen"

            # Start an UX interaction, return immediately here
            from auth import maybe_enroll_xpub
            maybe_enroll_xpub(sf_len=file_len, ux_reset=True)

            return None

        if cmd == 'msck':
            # Quick check to test if we have a wallet already installed.
            from multisig import MultisigWallet
            M, N, xfp_xor = unpack_from('<3I', args)

            return int(MultisigWallet.quick_check(M, N, xfp_xor))

        if cmd == 'stxn':
            # sign transaction
            txn_len, flags, txn_sha = unpack_from('<II32s', args)
            if txn_sha != self.file_checksum.digest():
                return b'err_Checksum'

            assert 50 < txn_len <= MAX_TXN_LEN, "bad txn len"

            from auth import sign_transaction
            sign_transaction(txn_len, (flags & STXN_FLAGS_MASK), txn_sha)
            return None

        if cmd == 'stok' or cmd == 'bkok' or cmd == 'smok' or cmd == 'pwok':
            # Have we finished (whatever) the transaction,
            # which needed user approval? If so, provide result.
            from auth import UserAuthorizedAction

            req = UserAuthorizedAction.active_request
            if not req:
                return b'err_No active request'

            if req.refused:
                UserAuthorizedAction.cleanup()
                return b'refu'

            if req.failed:
                rv = b'err_' + req.failed.encode()
                UserAuthorizedAction.cleanup()
                return rv

            if not req.result:
                # STILL waiting on user
                return None

            if cmd == 'pwok':
                # return new root xpub
                xpub = req.result
                UserAuthorizedAction.cleanup()
                return b'asci' + bytes(xpub, 'ascii')
            elif cmd == 'smok':
                # signed message done: just give them the signature
                addr, sig = req.address, req.result
                UserAuthorizedAction.cleanup()
                return pack('<4sI', 'smrx', len(addr)) + addr.encode() + sig
            else:
                # generic file response
                resp_len, sha = req.result
                UserAuthorizedAction.cleanup()
                return pack('<4sI32s', 'strx', resp_len, sha)

        if cmd == 'pass':
            # bip39 passphrase provided, maybe use it if authorized
            assert self.encrypted_req, 'must encrypt'
            from auth import start_bip39_passphrase
            from main import settings

            assert settings.get('words', True), 'no seed'
            assert len(args) < 400, 'too long'
            pw = str(args, 'utf8')
            assert len(pw) < 100, 'too long'

            return start_bip39_passphrase(pw)

        if cmd == 'back':
            # start backup: asks user, takes long time.
            from auth import start_remote_backup
            return start_remote_backup()

        if cmd == 'blkc':
            # report which blockchain we are configured for
            from chains import current_chain
            chain = current_chain()
            return b'asci' + chain.ctype

        if cmd == 'bagi':
            return self.handle_bag_number(args)

        if has_fatram:
            # HSM and user-related  features only larger-memory Mk3

            if cmd == 'hsms':
                # HSM mode "start" -- requires user approval
                if args:
                    file_len, file_sha = unpack_from('<I32s', args)
                    if file_sha != self.file_checksum.digest():
                        return b'err_Checksum'
                    assert 2 <= file_len <= (200 * 1000), "badlen"
                else:
                    file_len = 0

                # Start an UX interaction but return (mostly) immediately here
                from hsm_ux import start_hsm_approval
                await start_hsm_approval(sf_len=file_len, usb_mode=True)

                return None

            if cmd == 'hsts':
                # can always query HSM mode
                from hsm import hsm_status_report
                import ujson
                return b'asci' + ujson.dumps(hsm_status_report())

            if cmd == 'gslr':
                # get the value held in the Storage Locker
                assert hsm_active, 'need hsm'
                return b'biny' + hsm_active.fetch_storage_locker()

            # User Mgmt
            if cmd == 'nwur':  # new user
                from users import Users
                auth_mode, ul, sl = unpack_from('<BBB', args)
                username = bytes(args[3:3 + ul]).decode('ascii')
                secret = bytes(args[3 + ul:3 + ul + sl])

                return b'asci' + Users.create(username, auth_mode,
                                              secret).encode('ascii')

            if cmd == 'rmur':  # delete user
                from users import Users
                ul, = unpack_from('<B', args)
                username = bytes(args[1:1 + ul]).decode('ascii')

                return Users.delete(username)

            if cmd == 'user':  # auth user (HSM mode)
                from users import Users
                totp_time, ul, tl = unpack_from('<IBB', args)
                username = bytes(args[6:6 + ul]).decode('ascii')
                token = bytes(args[6 + ul:6 + ul + tl])

                if hsm_active:
                    # just queues these details, can't be checked until PSBT on-hand
                    hsm_active.usb_auth_user(username, token, totp_time)
                    return None
                else:
                    # dryrun/testing purposes: validate only, doesn't unlock nothing
                    return b'asci' + Users.auth_okay(username, token,
                                                     totp_time).encode('ascii')

        print("USB garbage: %s +[%d]" % (cmd, len(args)))

        return b'err_Unknown cmd'
Example #8
0
    async def handle(self, cmd, args):
        # Dispatch incoming message, and provide reply.

        try:
            cmd = bytes(cmd).decode()
        except:
            raise FramingError('decode')

        if cmd == 'dfu_':
            # only useful in factory, undocumented.
            return self.call_after(callgate.enter_dfu)

        if cmd == 'rebo':
            import machine
            return self.call_after(machine.reset)

        if cmd == 'logo':
            return self.call_after(callgate.show_logout)

        if cmd == 'ping':
            return b'biny' + args

        if cmd == 'upld':
            offset, total_size = unpack_from('<II', args)
            data = memoryview(args)[4 + 4:]

            return await self.handle_upload(offset, total_size, data)

        if cmd == 'dwld':
            offset, length, fileno = unpack_from('<III', args)
            return await self.handle_download(offset, length, fileno)

        if cmd == 'ncry':
            version, his_pubkey = unpack_from('<I64s', args)

            return self.handle_crypto_setup(version, his_pubkey)

        if cmd == 'vers':
            from version import get_mpy_version
            from callgate import get_bl_version

            # Returning: date, version(human), bootloader version, full date version
            # BUT: be ready for additions!
            rv = list(get_mpy_version())
            rv.insert(2, get_bl_version()[0])

            return b'asci' + ('\n'.join(rv)).encode()

        if cmd == 'sha2':
            return b'biny' + self.file_checksum.digest()

        if cmd == 'xpub':
            assert self.encrypted_req, 'must encrypt'
            return self.handle_xpub(str(args, 'ascii'))

        if cmd == 'mitm':
            assert self.encrypted_req, 'must encrypt'
            return await self.handle_mitm_check()

        if cmd == 'smsg':
            # sign message
            addr_fmt, len_subpath, len_msg = unpack_from('<III', args)
            subpath = args[12:12 + len_subpath]
            msg = args[12 + len_subpath:]
            assert len(msg) == len_msg, "badlen"

            from auth import sign_msg
            sign_msg(msg, subpath, addr_fmt)
            return None

        if cmd == 'p2sh':
            # show P2SH (probably multisig) address on screen (also provides it back)
            # - must provide redeem script, and list of [xfp+path]
            from auth import start_show_p2sh_address

            # new multsig goodness, needs mapping from xfp->path and M values
            addr_fmt, M, N, script_len = unpack_from('<IBBH', args)

            assert addr_fmt & AFC_SCRIPT
            assert 1 <= M <= N <= 20
            assert 30 <= script_len <= 520

            offset = 8
            witdeem_script = args[offset:offset + script_len]
            offset += script_len

            assert len(witdeem_script) == script_len

            xfp_paths = []
            for i in range(N):
                ln = args[offset]
                assert 2 <= ln <= 16, 'badlen'
                xfp_paths.append(unpack_from('<%dI' % ln, args, offset + 1))
                offset += (ln * 4) + 1

            assert offset == len(args)

            return b'asci' + start_show_p2sh_address(M, N, addr_fmt, xfp_paths,
                                                     witdeem_script)

        if cmd == 'show':
            # simple cases, older code: text subpath
            from auth import start_show_address

            addr_fmt, = unpack_from('<I', args)
            assert not (addr_fmt & AFC_SCRIPT)

            return b'asci' + start_show_address(addr_fmt, subpath=args[4:])

        if cmd == 'enrl':
            # Enroll new xpubkey to be involved in multisigs.
            # - text config file must already be uploaded

            file_len, file_sha = unpack_from('<I32s', args)
            if file_sha != self.file_checksum.digest():
                return b'err_Checksum'
            assert 100 < file_len <= (20 * 200), "badlen"

            # Start an UX interaction, return immediately here
            from auth import maybe_enroll_xpub
            maybe_enroll_xpub(sf_len=file_len, ux_reset=True)
            return None

        if cmd == 'msck':
            # Quick check to test if we have a wallet already installed.
            from multisig import MultisigWallet
            M, N, xfp_xor = unpack_from('<3I', args)

            return int(MultisigWallet.quick_check(M, N, xfp_xor))

        if cmd == 'stxn':
            # sign transaction
            txn_len, finalize, txn_sha = unpack_from('<II32s', args)
            if txn_sha != self.file_checksum.digest():
                return b'err_Checksum'

            assert 50 < txn_len <= MAX_TXN_LEN, "bad txn len"

            from auth import sign_transaction
            sign_transaction(txn_len, bool(finalize))
            return None

        if cmd == 'stok' or cmd == 'bkok' or cmd == 'smok' or cmd == 'pwok' or cmd == 'enok':
            # Have we finished (whatever) the transaction,
            # which needed user approval? If so, provide result.
            from auth import active_request, UserAuthorizedAction

            if not active_request:
                return b'err_No active request'

            if active_request.refused:
                UserAuthorizedAction.cleanup()
                return b'refu'

            if active_request.failed:
                rv = b'err_' + active_request.failed.encode()
                UserAuthorizedAction.cleanup()
                return rv

            if not active_request.result:
                # STILL waiting on user
                return None

            if cmd == 'pwok' or cmd == 'enok':
                # return new root xpub
                xpub = active_request.result
                UserAuthorizedAction.cleanup()
                return b'asci' + bytes(xpub, 'ascii')
            elif cmd == 'smok':
                # signed message done: just give them the signature
                addr, sig = active_request.address, active_request.result
                UserAuthorizedAction.cleanup()
                return pack('<4sI', 'smrx', len(addr)) + addr.encode() + sig
            else:
                # generic file response
                resp_len, sha = active_request.result
                UserAuthorizedAction.cleanup()
                return pack('<4sI32s', 'strx', resp_len, sha)

        if cmd == 'pass':
            # bip39 passphrase provided, maybe use it if authorized
            assert self.encrypted_req, 'must encrypt'
            from auth import start_bip39_passphrase
            from main import settings

            assert settings.get('words', True), 'no seed'
            assert len(args) < 400, 'too long'
            pw = str(args, 'utf8')
            assert len(pw) < 100, 'too long'

            return start_bip39_passphrase(pw)

        if cmd == 'back':
            # start backup: asks user, takes long time.
            from auth import start_remote_backup
            return start_remote_backup()

        if cmd == 'bagi':
            return self.handle_bag_number(args)

        if is_simulator() and cmd[0].isupper():
            # special hacky commands to support testing w/ the simulator
            from sim_usb import do_usb_command
            return do_usb_command(cmd, args)

        print("USB garbage: %s +[%d]" % (cmd, len(args)))

        return b'err_Unknown cmd'
Example #9
0
    async def handle(self, cmd, args):
        # Dispatch incoming message, and provide reply.

        cmd = bytes(cmd).decode()

        if cmd == 'dfu_':
            # only useful in factory, undocumented.
            return self.call_after(callgate.enter_dfu)

        if cmd == 'rebo':
            import machine
            return self.call_after(machine.reset)

        if cmd == 'logo':
            return self.call_after(callgate.show_logout)

        if cmd == 'ping':
            return b'biny' + args

        if cmd == 'upld':
            offset, total_size = unpack_from('<II', args)
            data = memoryview(args)[4 + 4:]

            return await self.handle_upload(offset, total_size, data)

        if cmd == 'dwld':
            offset, length, fileno = unpack_from('<III', args)
            return await self.handle_download(offset, length, fileno)

        if cmd == 'ncry':
            version, his_pubkey = unpack_from('<I64s', args)

            return self.handle_crypto_setup(version, his_pubkey)

        if cmd == 'vers':
            from version import get_mpy_version
            from callgate import get_bl_version

            # Returning: date, version(human), bootloader version, full date version
            # BUT: be ready for additions!
            rv = list(get_mpy_version())
            rv.insert(2, get_bl_version()[0])

            return b'asci' + ('\n'.join(rv)).encode()

        if cmd == 'sha2':
            return b'biny' + self.file_checksum.digest()

        if cmd == 'xpub':
            assert self.encrypted_req, 'must encrypt'
            return self.handle_xpub(str(args, 'ascii'))

        if cmd == 'mitm':
            assert self.encrypted_req, 'must encrypt'
            return await self.handle_mitm_check()

        if cmd == 'smsg':
            # sign message
            addr_fmt, len_subpath, len_msg = unpack_from('<III', args)
            subpath = args[12:12 + len_subpath]
            msg = args[12 + len_subpath:]
            assert len(msg) == len_msg, "badlen"

            from auth import sign_msg
            sign_msg(msg, subpath, addr_fmt)
            return None

        if cmd == 'show':
            # show address on screen (also provides it back)
            addr_fmt, = unpack_from('<I', args)
            subpath = args[4:]
            from auth import start_show_address

            return b'asci' + start_show_address(subpath, addr_fmt)

        if cmd == 'stxn':
            # sign transaction
            txn_len, finalize, txn_sha = unpack_from('<II32s', args)
            if txn_sha != self.file_checksum.digest():
                return b'err_Checksum'

            assert 50 < txn_len <= MAX_TXN_LEN, "bad txn len"

            from auth import sign_transaction
            sign_transaction(txn_len, bool(finalize))
            return None

        if cmd == 'stok' or cmd == 'bkok' or cmd == 'smok' or cmd == 'pwok':
            # Have we finished (whatever) the transaction,
            # which needed user approval? If so, provide result.
            from auth import active_request, UserAuthorizedAction

            if not active_request:
                return b'err_No active request'

            if active_request.refused:
                UserAuthorizedAction.cleanup()
                return b'refu'

            if active_request.failed:
                rv = b'err_' + active_request.failed.encode()
                UserAuthorizedAction.cleanup()
                return rv

            if not active_request.result:
                # STILL waiting on user
                return None

            if cmd == 'pwok':
                # return new root xpub
                xpub = active_request.result
                UserAuthorizedAction.cleanup()
                return b'asci' + bytes(xpub, 'ascii')
            elif cmd == 'smok':
                # signed message done: just give them the signature
                addr, sig = active_request.address, active_request.result
                UserAuthorizedAction.cleanup()
                return pack('<4sI', 'smrx', len(addr)) + addr.encode() + sig
            else:
                # generic file response
                resp_len, sha = active_request.result
                UserAuthorizedAction.cleanup()
                return pack('<4sI32s', 'strx', resp_len, sha)

        if cmd == 'pass':
            # bip39 passphrase provided, maybe use it if authorized
            assert self.encrypted_req, 'must encrypt'
            from auth import start_bip39_passphrase

            assert len(args) < 400, 'too long'
            pw = str(args, 'utf8')
            assert len(pw) < 100, 'too long'

            return start_bip39_passphrase(pw)

        if cmd == 'back':
            # start backup: asks user, takes long time.
            from auth import start_remote_backup
            return start_remote_backup()

        if cmd == 'bagi':
            return self.handle_bag_number(args)

        if is_simulator() and cmd[0].isupper():
            # special hacky commands to support testing w/ the simulator
            from sim_usb import do_usb_command
            return do_usb_command(cmd, args)

        print("USB garbage: %s +[%d]" % (cmd, len(args)))

        return b'err_Unknown cmd'