mmgen-wallet/mmgen/seedsplit.py

#!/usr/bin/env python3
#
# mmgen = Multi-Mode GENerator, command-line Bitcoin cold storage solution
# Copyright (C)2013-2023 The MMGen Project <mmgen@tuta.io>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
seedsplit: Seed split classes and methods for the MMGen suite
"""

from .color import yellow
from .obj import MMGenPWIDString,MMGenIdx
from .subseed import *
from .crypto import Crypto

class SeedShareIdx(MMGenIdx):
	max_val = 1024

class SeedShareCount(SeedShareIdx):
	min_val = 2

class MasterShareIdx(MMGenIdx):
	max_val = 1024

class SeedSplitSpecifier(str,Hilite,InitErrors,MMGenObject):
	color = 'red'
	def __new__(cls,s):
		if type(s) == cls:
			return s
		try:
			arr = s.split(':')
			assert len(arr) in (2,3), 'cannot be parsed'
			a,b,c = arr if len(arr) == 3 else ['default'] + arr
			me = str.__new__(cls,s)
			me.id = SeedSplitIDString(a)
			me.idx = SeedShareIdx(b)
			me.count = SeedShareCount(c)
			assert me.idx <= me.count, 'share index greater than share count'
			return me
		except Exception as e:
			return cls.init_fail(e,s)

def is_seed_split_specifier(s):
	return get_obj( SeedSplitSpecifier, s=s, silent=True, return_bool=True )

class SeedSplitIDString(MMGenPWIDString):
	desc = 'seed split ID string'

class SeedShareList(SubSeedList):
	have_short = False
	split_type = 'N-of-N'

	count  = ImmutableAttr(SeedShareCount)
	id_str = ImmutableAttr(SeedSplitIDString)

	def __init__(self,parent_seed,count,id_str=None,master_idx=None,debug_last_share=False):
		self.member_type = SeedShare
		self.parent_seed = parent_seed
		self.id_str = id_str or 'default'
		self.count = count
		self.len = 2 # placeholder, always overridden

		def make_master_share():
			for nonce in range(SeedShare.max_nonce+1):
				ms = SeedShareMaster(self,master_idx,nonce)
				if ms.sid == parent_seed.sid:
					if parent_seed.cfg.debug_subseed:
						msg(f'master_share seed ID collision with parent seed, incrementing nonce to {nonce+1}')
				else:
					return ms
			die( 'SubSeedNonceRangeExceeded', 'nonce range exceeded' )

		def last_share_debug(last_share):
			if not debug_last_share:
				return False
			sid_len = self.debug_last_share_sid_len
			lsid = last_share.sid[:sid_len]
			psid = parent_seed.sid[:sid_len]
			ssids = [d[:sid_len] for d in self.data['long'].keys]
			return (lsid in ssids or lsid == psid)

		self.master_share = make_master_share() if master_idx else None

		for nonce in range(SeedShare.max_nonce+1):
			self.nonce_start = nonce
			self.data = { 'long': IndexedDict(), 'short': IndexedDict() } # 'short' is required as a placeholder
			if self.master_share:
				self.data['long'][self.master_share.sid] = (1,self.master_share.nonce)
			self._generate(count-1)
			self.last_share = ls = SeedShareLast(self)
			if last_share_debug(ls) or ls.sid in self.data['long'] or ls.sid == parent_seed.sid:
				# collision: throw out entire split list and redo with new start nonce
				if parent_seed.cfg.debug_subseed:
					self._collision_debug_msg(ls.sid,count,nonce,'nonce_start',debug_last_share)
			else:
				self.data['long'][ls.sid] = (count,nonce)
				break
		else:
			die( 'SubSeedNonceRangeExceeded', 'nonce range exceeded' )

		if parent_seed.cfg.debug_subseed:
			A = parent_seed.data
			B = self.join().data
			assert A == B, f'Data mismatch!\noriginal seed: {A!r}\nrejoined seed: {B!r}'

	def get_share_by_idx(self,idx,base_seed=False):
		if idx < 1 or idx > self.count:
			die( 'RangeError', f'{idx}: share index out of range' )
		elif idx == self.count:
			return self.last_share
		elif self.master_share and idx == 1:
			return self.master_share if base_seed else self.master_share.derived_seed
		else:
			ss_idx = SubSeedIdx(str(idx) + 'L')
			return self.get_subseed_by_ss_idx(ss_idx)

	def get_share_by_seed_id(self,sid,base_seed=False):
		if sid == self.data['long'].key(self.count-1):
			return self.last_share
		elif self.master_share and sid == self.data['long'].key(0):
			return self.master_share if base_seed else self.master_share.derived_seed
		else:
			return self.get_subseed_by_seed_id(sid)

	def join(self):
		return Seed.join_shares(
			self.parent_seed.cfg,
			[self.get_share_by_idx(i+1) for i in range(len(self))] )

	def format(self):
		assert self.split_type == 'N-of-N'
		fs1 = '    {}\n'
		fs2 = '{i:>5}: {}\n'
		mfs1,mfs2,midx,msid = ('','','','')
		if self.master_share:
			mfs1,mfs2 = (' with master share #{} ({})',' (master share #{})')
			midx,msid = (self.master_share.idx,self.master_share.sid)

		hdr  = '    {} {} ({} bits)\n'.format('Seed:',self.parent_seed.sid.hl(),self.parent_seed.bitlen)
		hdr += '    {} {c}-of-{c} (XOR){m}\n'.format('Split Type:',c=self.count,m=mfs1.format(midx,msid))
		hdr += '    {} {}\n\n'.format('ID String:',self.id_str.hl())
		hdr += fs1.format('Shares')
		hdr += fs1.format('------')

		sl = self.data['long'].keys
		body1 = fs2.format(sl[0]+mfs2.format(midx),i=1)
		body = (fs2.format(sl[n],i=n+1) for n in range(1,len(self)))

		return hdr + body1 + ''.join(body)

class SeedShareBase(MMGenObject):

	@property
	def fn_stem(self):
		pl = self.parent_list
		msdata = f'_with_master{pl.master_share.idx}' if pl.master_share else ''
		return '{}-{}-{}of{}{}[{}]'.format(
			pl.parent_seed.sid,
			pl.id_str,
			self.idx,
			pl.count,
			msdata,
			self.sid)

	@property
	def desc(self):
		return self.get_desc()

	def get_desc(self,ui=False):
		pl = self.parent_list
		mss = f', with master share #{pl.master_share.idx}' if pl.master_share else ''
		if ui:
			m   = ( yellow("(share {} of {} of ")
					+ pl.parent_seed.sid.hl()
					+ yellow(', split id ')
					+ pl.id_str.hl2(encl='‘’')
					+ yellow('{})') )
		else:
			m = "share {} of {} of " + pl.parent_seed.sid + ", split id '" + pl.id_str + "'{}"
		return m.format(self.idx,pl.count,mss)

class SeedShare(SeedShareBase,SubSeed):

	@staticmethod
	def make_subseed_bin(parent_list,idx:int,nonce:int,length:str):
		seed = parent_list.parent_seed
		assert parent_list.have_short == False
		assert length == 'long'
		# field maximums: id_str: none (256 chars), count: 65535 (1024), idx: 65535 (1024), nonce: 65535 (1000)
		scramble_key = (
			f'{parent_list.split_type}:{parent_list.id_str}:'.encode() +
			parent_list.count.to_bytes(2,'big') +
			idx.to_bytes(2,'big') +
			nonce.to_bytes(2,'big')
		)
		if parent_list.master_share:
			scramble_key += (
				b':master:' +
				parent_list.master_share.idx.to_bytes(2,'big')
			)
		return Crypto(parent_list.parent_seed.cfg).scramble_seed(seed.data,scramble_key)[:seed.byte_len]

class SeedShareLast(SeedShareBase,SeedBase):

	idx = ImmutableAttr(SeedShareIdx)
	nonce = 0

	def __init__(self,parent_list):
		self.idx = parent_list.count
		self.parent_list = parent_list
		SeedBase.__init__(
			self,
			parent_list.parent_seed.cfg,
			seed_bin=self.make_subseed_bin(parent_list) )

	@staticmethod
	def make_subseed_bin(parent_list):
		seed_list = (parent_list.get_share_by_idx(i+1) for i in range(len(parent_list)))
		seed = parent_list.parent_seed

		ret = int(seed.data.hex(),16)
		for ss in seed_list:
			ret ^= int(ss.data.hex(),16)

		return ret.to_bytes(seed.byte_len,'big')

class SeedShareMaster(SeedBase,SeedShareBase):

	idx   = ImmutableAttr(MasterShareIdx)
	nonce = ImmutableAttr(int,typeconv=False)

	def __init__(self,parent_list,idx,nonce):
		self.idx = idx
		self.nonce = nonce
		self.parent_list = parent_list
		self.cfg = parent_list.parent_seed.cfg

		SeedBase.__init__( self, self.cfg, self.make_base_seed_bin() )

		self.derived_seed = SeedBase(
			self.cfg,
			self.make_derived_seed_bin( parent_list.id_str, parent_list.count )
		)

	@property
	def fn_stem(self):
		return '{}-MASTER{}[{}]'.format(
			self.parent_list.parent_seed.sid,
			self.idx,
			self.sid )

	def make_base_seed_bin(self):
		seed = self.parent_list.parent_seed
		# field maximums: idx: 65535 (1024)
		scramble_key = b'master_share:' + self.idx.to_bytes(2,'big') + self.nonce.to_bytes(2,'big')
		return Crypto(self.cfg).scramble_seed(seed.data,scramble_key)[:seed.byte_len]

	# Don't bother with avoiding seed ID collision here, as sid of derived seed is not used
	# by user as an identifier
	def make_derived_seed_bin(self,id_str,count):
		# field maximums: id_str: none (256 chars), count: 65535 (1024)
		scramble_key = id_str.encode() + b':' + count.to_bytes(2,'big')
		return Crypto(self.cfg).scramble_seed(self.data,scramble_key)[:self.byte_len]

	def get_desc(self,ui=False):
		psid = self.parent_list.parent_seed.sid
		mss = f'master share #{self.idx} of '
		return yellow('(' + mss) + psid.hl() + yellow(')') if ui else mss + psid

class SeedShareMasterJoining(SeedShareMaster):

	id_str = ImmutableAttr(SeedSplitIDString)
	count  = ImmutableAttr(SeedShareCount)

	def __init__(self,cfg,idx,base_seed,id_str,count):

		SeedBase.__init__( self, cfg, seed_bin=base_seed.data )

		self.cfg = cfg
		self.id_str = id_str or 'default'
		self.count = count
		self.derived_seed = SeedBase( cfg, self.make_derived_seed_bin(self.id_str,self.count) )

def join_shares(
		cfg,
		seed_list,
		master_idx = None,
		id_str     = None ):

	if not hasattr(seed_list,'__next__'): # seed_list can be iterator or iterable
		seed_list = iter(seed_list)

	class d(object):
		byte_len,ret,count = None,0,0

	def add_share(ss):
		if d.byte_len:
			assert ss.byte_len == d.byte_len, f'Seed length mismatch! {ss.byte_len} != {d.byte_len}'
		else:
			d.byte_len = ss.byte_len
		d.ret ^= int(ss.data.hex(),16)
		d.count += 1

	if master_idx:
		master_share = next(seed_list)

	for ss in seed_list:
		add_share(ss)

	if master_idx:
		add_share(SeedShareMasterJoining( cfg, master_idx, master_share, id_str, d.count+1 ).derived_seed)

	SeedShareCount(d.count) # check that d.count is in valid range

	return Seed( cfg, seed_bin=d.ret.to_bytes(d.byte_len,'big') )