From 52fdf29b672eec91c76e73db4fc14d3a55f6dd10 Mon Sep 17 00:00:00 2001
From: philemon <mmgen-py@yandex.com>
Date: Mon, 7 Aug 2017 22:02:24 +0300
Subject: [PATCH] new classes: KeyGenerator,AddrGenerator,PrivKey; read-only
 attrs rewrite

- OO rewrite of key/addr generation interface (KeyGenerator,AddrGenerator)
- New data objects: PrivKey,PubKey,WifKey
- rewrite of read-only attr implementation for addr/tx/tw list entries
  (MMGenImmutableAttr,MMGenListItemAttr descriptors)
- txsign: build key list of addrlist objects rather than addr,key tuples
---
 mmgen/addr.py                  | 242 +++++++++++++++------------------
 mmgen/main_addrgen.py          |   2 +-
 mmgen/main_addrimport.py       |   2 +-
 mmgen/main_passgen.py          |   2 +-
 mmgen/main_tool.py             |   2 +-
 mmgen/main_txbump.py           |   2 +-
 mmgen/main_txcreate.py         |   2 +-
 mmgen/main_txdo.py             |   4 +-
 mmgen/main_txsend.py           |   2 +-
 mmgen/main_txsign.py           |   4 +-
 mmgen/main_wallet.py           |   2 +-
 mmgen/obj.py                   | 215 ++++++++++++++++++++---------
 mmgen/share/Opts.py            |   8 +-
 mmgen/tw.py                    |  22 ++-
 mmgen/tx.py                    | 106 ++++++---------
 mmgen/txsign.py                |  52 +++----
 scripts/compute-file-chksum.py |   8 +-
 scripts/tx-old2new.py          |  90 +++++-------
 test/gentest.py                |  47 +++----
 test/test.py                   |   2 +-
 test/tooltest.py               |   2 +-
 21 files changed, 429 insertions(+), 389 deletions(-)

diff --git a/mmgen/addr.py b/mmgen/addr.py
index 35df9314..6297a8ef 100755
--- a/mmgen/addr.py
+++ b/mmgen/addr.py
@@ -23,96 +23,93 @@ addr.py:  Address generation/display routines for the MMGen suite
 from hashlib import sha256,sha512
 from binascii import hexlify,unhexlify
 from mmgen.common import *
-from mmgen.bitcoin import hex2wif,wif2hex,wif_is_compressed
 from mmgen.obj import *
-from mmgen.tx import *
-from mmgen.tw import *
 
 pnm = g.proj_name
 
-def _test_for_secp256k1(silent=False):
-	no_secp256k1_errmsg = """
-secp256k1 library unavailable.  Using (slow) native Python ECDSA library for address generation.
-"""
-	try:
-		from mmgen.secp256k1 import priv2pub
-		assert priv2pub(os.urandom(32),1)
-	except:
-		if not silent: msg(no_secp256k1_errmsg.strip())
-		return False
-	return True
+class AddrGenerator(MMGenObject):
+	def __new__(cls,atype):
+		d = {
+			'p2pkh':  AddrGeneratorP2PKH,
+			'segwit': AddrGeneratorSegwit
+		}
+		assert atype in d
+		return super(cls,cls).__new__(d[atype])
 
-def _pubhex2addr(pubhex,mmtype):
-	if mmtype == 'L':
+class AddrGeneratorP2PKH(MMGenObject):
+	desc = 'p2pkh'
+	def to_addr(self,pubhex):
+		assert type(pubhex) == PubKey
 		from mmgen.bitcoin import hexaddr2addr,hash160
-		return hexaddr2addr(hash160(pubhex))
-	elif mmtype == 'S':
+		return BTCAddr(hexaddr2addr(hash160(pubhex)))
+
+	def to_segwit_redeem_script(self,pubhex):
+		raise NotImplemented
+
+class AddrGeneratorSegwit(MMGenObject):
+	desc = 'segwit'
+	def to_addr(self,pubhex):
+		assert pubhex.compressed
 		from mmgen.bitcoin import pubhex2segwitaddr
-		return pubhex2segwitaddr(pubhex)
-	else:
-		die(2,"'{}': mmtype unrecognized".format(mmtype))
+		return BTCAddr(pubhex2segwitaddr(pubhex))
 
-def _privhex2addr_python(privhex,compressed,mmtype):
-	assert compressed or mmtype != 'S'
-	from mmgen.bitcoin import privnum2pubhex
-	pubhex = privnum2pubhex(int(privhex,16),compressed=compressed)
-	return _pubhex2addr(pubhex,mmtype=mmtype)
+	def to_segwit_redeem_script(self,pubhex):
+		assert pubhex.compressed
+		from mmgen.bitcoin import pubhex2redeem_script
+		return HexStr(pubhex2redeem_script(pubhex))
 
-def _privhex2addr_secp256k1(privhex,compressed,mmtype):
-	assert compressed or mmtype != 'S'
-	from mmgen.secp256k1 import priv2pub
-	pubhex = hexlify(priv2pub(unhexlify(privhex),int(compressed)))
-	return _pubhex2addr(pubhex,mmtype=mmtype)
+class KeyGenerator(MMGenObject):
+	def __new__(cls,generator=None,silent=False):
+		if cls.test_for_secp256k1(silent=silent) and generator != 1:
+			if opt.key_generator != 1:
+				return super(cls,cls).__new__(KeyGeneratorSecp256k1)
+		else:
+			msg('Using (slow) native Python ECDSA library for address generation')
+			return super(cls,cls).__new__(KeyGeneratorPython)
 
-def _wif2addr_python(wif,mmtype):
-	privhex = wif2hex(wif)
-	if not privhex: return False
-	return _privhex2addr_python(privhex,wif_is_compressed(wif),mmtype=mmtype)
+	@classmethod
+	def test_for_secp256k1(self,silent=False):
+		try:
+			from mmgen.secp256k1 import priv2pub
+			assert priv2pub(os.urandom(32),1)
+			return True
+		except:
+			return False
 
-def _wif2addr_secp256k1(wif,mmtype):
-	privhex = wif2hex(wif)
-	if not privhex: return False
-	return _privhex2addr_secp256k1(privhex,wif_is_compressed(wif),mmtype=mmtype)
-
-def keygen_wif2pubhex(wif,selector):
-	privhex = wif2hex(wif)
-	if not privhex: return False
-	if selector == 1:
-		from mmgen.secp256k1 import priv2pub
-		return hexlify(priv2pub(unhexlify(privhex),int(wif_is_compressed(wif))))
-	elif selector == 0:
+class KeyGeneratorPython(KeyGenerator):
+	desc = 'python-ecdsa'
+	def to_pubhex(self,privhex):
+		assert type(privhex) == PrivKey
 		from mmgen.bitcoin import privnum2pubhex
-		return privnum2pubhex(int(privhex,16),compressed=wif_is_compressed(wif))
-
-def keygen_selector(generator=None):
-	if _test_for_secp256k1() and generator != 1:
-		if opt.key_generator != 1:
-			return 1
-	msg('Using (slow) native Python ECDSA library for address generation')
-	return 0
-
-def get_wif2addr_f(generator=None):
-	gen = keygen_selector(generator=generator)
-	return (_wif2addr_python,_wif2addr_secp256k1)[gen]
-
-def get_privhex2addr_f(generator=None):
-	gen = keygen_selector(generator=generator)
-	return (_privhex2addr_python,_privhex2addr_secp256k1)[gen]
+		return PubKey(privnum2pubhex(int(privhex,16),compressed=privhex.compressed),compressed=privhex.compressed)
 
+class KeyGeneratorSecp256k1(KeyGenerator):
+	desc = 'secp256k1'
+	def to_pubhex(self,privhex):
+		assert type(privhex) == PrivKey
+		from mmgen.secp256k1 import priv2pub
+		return PubKey(hexlify(priv2pub(unhexlify(privhex),int(privhex.compressed))),compressed=privhex.compressed)
 
 class AddrListEntry(MMGenListItem):
-	attrs = 'idx','addr','label','wif','sec'
+	reassign_ok = 'label',
+	addr  = MMGenListItemAttr('addr','BTCAddr')
 	idx   = MMGenListItemAttr('idx','AddrIdx')
-	wif   = MMGenListItemAttr('wif','WifKey')
+	label = MMGenListItemAttr('label','TwComment')
+	sec   = MMGenImmutableAttr('sec',PrivKey)
+
+class PasswordListEntry(MMGenListItem):
+	reassign_ok = 'label',
+	passwd = MMGenImmutableAttr('passwd',unicode) # TODO: create Password type
+	idx    = MMGenListItemAttr('idx','AddrIdx')
+	label  = MMGenListItemAttr('label','TwComment')
+	sec    = MMGenImmutableAttr('sec',PrivKey)
 
 class AddrListChksum(str,Hilite):
 	color = 'pink'
 	trunc_ok = False
 
 	def __new__(cls,addrlist):
-		els = ['addr','wif'] if addrlist.has_keys else ['sec'] if addrlist.gen_passwds else ['addr']
-		lines = [' '.join([str(e.idx)] + [getattr(e,f) for f in els]) for e in addrlist.data]
-#		print '[{}]'.format(' '.join(lines))
+		lines = [' '.join(addrlist.chksum_rec_f(e)) for e in addrlist.data]
 		return str.__new__(cls,make_chksum_N(' '.join(lines), nchars=16, sep=True))
 
 class AddrListIDStr(unicode,Hilite):
@@ -159,10 +156,11 @@ class AddrList(MMGenObject): # Address info for a single seed ID
 Record this checksum: it will be used to verify the address file in the future
 """.strip(),
 	'check_chksum': 'Check this value against your records',
-	'removed_dups': """
-Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
+	'removed_dup_keys': """
+Removed %s duplicate WIF key%s from keylist (also in {pnm} key-address file
 """.strip().format(pnm=pnm)
 	}
+	entry_type = AddrListEntry
 	main_key  = 'addr'
 	data_desc = 'address'
 	file_desc = 'addresses'
@@ -175,6 +173,7 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 	ext      = 'addrs'
 	dfl_mmtype = MMGenAddrType('L')
 	cook_hash_rounds = 10  # not too many rounds, so hand decoding can still be feasible
+	chksum_rec_f = lambda foo,e: (str(e.idx), e.addr)
 
 	def __init__(self,addrfile='',al_id='',adata=[],seed='',addr_idxs='',src='',
 					addrlist='',keylist='',mmtype=None,do_chksum=True,chksum_only=False):
@@ -196,7 +195,7 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 			adata = AddrListList([AddrListEntry(addr=a) for a in set(addrlist)])
 		elif keylist:            # data from flat key list
 			self.al_id = None
-			adata = AddrListList([AddrListEntry(wif=k) for k in set(keylist)])
+			adata = AddrListList([AddrListEntry(sec=PrivKey(wif=k)) for k in set(keylist)])
 		elif seed or addr_idxs:
 			die(3,'Must specify both seed and addr indexes')
 		elif al_id or adata:
@@ -233,15 +232,17 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 
 	def generate(self,seed,addrnums,compressed):
 		assert type(addrnums) is AddrIdxList
-		assert compressed in (True,False,None)
+		assert type(compressed) is bool
 
 		seed = seed.get_data()
 		seed = self.cook_seed(seed)
 
 		if self.gen_addrs:
-			privhex2addr_f = get_privhex2addr_f() # choose internal ECDSA or secp256k1 generator
+			kg = KeyGenerator()
+			ag = AddrGenerator(('p2pkh','segwit')[self.al_id.mmtype=='S'])
 
 		t_addrs,num,pos,out = len(addrnums),0,0,AddrListList()
+		le = self.entry_type
 
 		while pos != t_addrs:
 			seed = sha512(seed).digest()
@@ -254,21 +255,17 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 			if not g.debug:
 				qmsg_r('\rGenerating %s #%s (%s of %s)' % (self.gen_desc,num,pos,t_addrs))
 
-			e = AddrListEntry(idx=num)
+			e = le(idx=num)
 
 			# Secret key is double sha256 of seed hash round /num/
-			sec = sha256(sha256(seed).digest()).hexdigest()
+			e.sec = PrivKey(sha256(sha256(seed).digest()).digest(),compressed)
 
 			if self.gen_addrs:
-				e.addr = privhex2addr_f(sec,compressed=compressed,mmtype=self.al_id.mmtype)
+				e.addr = ag.to_addr(kg.to_pubhex(e.sec))
 
-			if self.gen_keys:
-				e.wif = hex2wif(sec,compressed=compressed)
-				if opt.b16: e.sec = sec
-
-			if self.gen_passwds:
-				e.sec = self.make_passwd(sec)
-				dmsg('Key {:>03}: {}'.format(pos,sec))
+			if type(self) == PasswordList:
+				e.passwd = unicode(self.make_passwd(e.sec)) # TODO - own type
+				dmsg('Key {:>03}: {}'.format(pos,e.passwd))
 
 			out.append(e)
 			if g.debug: print 'generate():\n', e.pformat()
@@ -347,62 +344,38 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 			except: pass
 		return d
 
-	def flat_list(self):
-		class AddrListFlatEntry(AddrListEntry):
-			attrs = 'mmid','addr','wif'
-		return [AddrListFlatEntry(mmid='{}:{}'.format(self.al_id,e.idx),addr=e.addr,wif=e.wif)
-			for e in self.data]
-
-	def remove_dups(self,cmplist,key='wif'):
+	def remove_dup_keys(self,cmplist):
+		assert self.has_keys
 		pop_list = []
 		for n,d in enumerate(self.data):
-			if getattr(d,key) == None: continue
 			for e in cmplist.data:
-				if getattr(e,key) and getattr(e,key) == getattr(d,key):
+				if e.sec.wif == d.sec.wif:
 					pop_list.append(n)
 		for n in reversed(pop_list): self.data.pop(n)
 		if pop_list:
-			vmsg(self.msgs['removed_dups'] % (len(pop_list),suf(removed,'s')))
+			vmsg(self.msgs['removed_dup_keys'] % (len(pop_list),suf(removed,'s')))
 
-	def add_wifs(self,al_key):
-		if not al_key: return
+	def add_wifs(self,key_list):
+		if not key_list: return
 		for d in self.data:
-			for e in al_key.data:
-				if e.addr and e.wif and e.addr == d.addr:
-					d.wif = e.wif
+			for e in key_list.data:
+				if e.addr and e.sec and e.addr == d.addr:
+					d.sec = e.sec
 
 	def list_missing(self,key):
 		return [d.addr for d in self.data if not getattr(d,key)]
 
-	def get(self,key):
-		return [getattr(d,key) for d in self.data if getattr(d,key)]
-
-	def get_addrs(self): return self.get('addr')
-	def get_wifs(self):  return self.get('wif')
-	def get_addr_wif_pairs(self):
-		return [(d.addr,d.wif) for d in self.data if hasattr(d,'wif')]
-
-	def generate_addrs_from_keylist(self):
-		wif2addr_f = get_wif2addr_f()
+	def generate_addrs_from_keys(self):
+		kg = KeyGenerator()
+		ag = AddrGenerator('p2pkh')
 		d = self.data
 		for n,e in enumerate(d,1):
 			qmsg_r('\rGenerating addresses from keylist: %s/%s' % (n,len(d)))
-			e.addr = wif2addr_f(e.wif,mmtype='L') # 'L' == p2pkh
+			e.addr = ag.to_addr(kg.to_pubhex(e.sec))
 		qmsg('\rGenerated addresses from keylist: %s/%s ' % (n,len(d)))
 
 	def format(self,enable_comments=False):
 
-		def check_attrs(key,desc):
-			for e in self.data:
-				if not getattr(e,key):
-					die(3,'missing %s in addr data' % desc)
-
-		if type(self) not in (KeyList,PasswordList): check_attrs('addr','addresses')
-
-		if self.has_keys:
-			if opt.b16: check_attrs('sec','hex keys')
-			check_attrs('wif','wif keys')
-
 		out = [self.msgs['file_header']+'\n']
 		if self.chksum:
 			out.append(u'# {} data checksum for {}: {}'.format(
@@ -421,14 +394,14 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 		for e in self.data:
 			c = ' '+e.label if enable_comments and e.label else ''
 			if type(self) == KeyList:
-				out.append(fs.format(e.idx, 'wif: '+e.wif,c))
+				out.append(fs.format(e.idx,'wif: {}'.format(e.sec.wif),c))
 			elif type(self) == PasswordList:
-				out.append(fs.format(e.idx, e.sec, c))
+				out.append(fs.format(e.idx,e.passwd,c))
 			else: # First line with idx
-				out.append(fs.format(e.idx, e.addr,c))
+				out.append(fs.format(e.idx,e.addr,c))
 				if self.has_keys:
 					if opt.b16: out.append(fs.format('', 'hex: '+e.sec,c))
-					out.append(fs.format('', 'wif: '+e.wif,c))
+					out.append(fs.format('', 'wif: '+e.sec.wif,c))
 
 		out.append('}')
 		self.fmt_data = '\n'.join([l.rstrip() for l in out]) + '\n'
@@ -439,6 +412,7 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 			return 'Key-address file has odd number of lines'
 
 		ret = AddrListList()
+		le = self.entry_type
 
 		while lines:
 			l = lines.pop(0)
@@ -452,7 +426,7 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 
 			if len(d) != 3: d.append('')
 
-			a = AddrListEntry(**{'idx':int(d[0]),self.main_key:d[1],'label':d[2]})
+			a = le(**{'idx':int(d[0]),self.main_key:d[1],'label':d[2]})
 
 			if self.has_keys:
 				l = lines.pop(0)
@@ -463,17 +437,18 @@ Removed %s duplicate wif key%s from keylist (also in {pnm} key-address file
 				if not is_wif(d[1]):
 					return "'%s': invalid Bitcoin key" % d[1]
 
-				a.wif = d[1]
+				a.sec = PrivKey(wif=d[1])
 
 			ret.append(a)
 
 		if self.has_keys and keypress_confirm('Check key-to-address validity?'):
-			wif2addr_f = get_wif2addr_f()
+			kg = KeyGenerator()
+			ag = AddrGenerator(('p2pkh','segwit')[self.al_id.mmtype=='S'])
 			llen = len(ret)
 			for n,e in enumerate(ret):
 				msg_r('\rVerifying keys %s/%s' % (n+1,llen))
-				if e.addr != wif2addr_f(e.wif,mmtype=self.al_id.mmtype):
-					return "Key doesn't match address!\n  %s\n  %s" % (e.wif,e.addr)
+				if e.addr != ag.to_addr(kg.to_pubhex(e.sec)):
+					return "Key doesn't match address!\n  %s\n  %s" % (e.sec.wif,e.addr)
 			msg(' - done')
 
 		return ret
@@ -539,6 +514,7 @@ class KeyAddrList(AddrList):
 	gen_keys = True
 	has_keys = True
 	ext      = 'akeys'
+	chksum_rec_f = lambda foo,e: (str(e.idx), e.addr, e.sec.wif)
 
 class KeyList(AddrList):
 	msgs = {
@@ -557,6 +533,7 @@ class KeyList(AddrList):
 	gen_keys = True
 	has_keys = True
 	ext      = 'keys'
+	chksum_rec_f = lambda foo,e: (str(e.idx), e.addr, e.sec.wif)
 
 class PasswordList(AddrList):
 	msgs = {
@@ -573,7 +550,8 @@ class PasswordList(AddrList):
 Record this checksum: it will be used to verify the password file in the future
 """.strip()
 	}
-	main_key    = 'sec'
+	entry_type  = PasswordListEntry
+	main_key    = 'passwd'
 	data_desc   = 'password'
 	file_desc   = 'passwords'
 	gen_desc    = 'password'
@@ -589,6 +567,7 @@ Record this checksum: it will be used to verify the password file in the future
 		'b58': { 'min_len': 8 , 'max_len': 36 ,'dfl_len': 20, 'desc': 'base-58 password' },
 		'b32': { 'min_len': 10 ,'max_len': 42 ,'dfl_len': 24, 'desc': 'base-32 password' }
 		}
+	chksum_rec_f = lambda foo,e: (str(e.idx), e.passwd)
 
 	def __init__(self,infile=None,seed=None,pw_idxs=None,pw_id_str=None,pw_len=None,pw_fmt=None,
 				chksum_only=False,chk_params_only=False):
@@ -605,7 +584,7 @@ Record this checksum: it will be used to verify the password file in the future
 			self.set_pw_len(pw_len)
 			if chk_params_only: return
 			self.al_id = AddrListID(seed.sid,MMGenPasswordType('P'))
-			self.data = self.generate(seed,pw_idxs,compressed=None)
+			self.data = self.generate(seed,pw_idxs,compressed=False)
 
 		self.num_addrs = len(self.data)
 		self.fmt_data = ''
@@ -677,7 +656,6 @@ Record this checksum: it will be used to verify the password file in the future
 		dmsg('Seed: {}\nCooked seed: {}\nCooked seed len: {}'.format(hexlify(seed),hexlify(cseed),len(cseed)))
 		return sha256_rounds(cseed,self.cook_hash_rounds)
 
-
 class AddrData(MMGenObject):
 	msgs = {
 	'too_many_acct_addresses': """
diff --git a/mmgen/main_addrgen.py b/mmgen/main_addrgen.py
index f89125ab..76e4cf68 100755
--- a/mmgen/main_addrgen.py
+++ b/mmgen/main_addrgen.py
@@ -41,7 +41,7 @@ note_secp256k1 = """
 If available, the secp256k1 library will be used for address generation.
 """.strip()
 
-def opts_data(): return {
+opts_data = lambda: {
 	'sets': [('print_checksum',True,'quiet',True)],
 	'desc': """Generate a range or list of {desc} from an {pnm} wallet,
                   mnemonic, seed or brainwallet""".format(desc=gen_desc,pnm=g.proj_name),
diff --git a/mmgen/main_addrimport.py b/mmgen/main_addrimport.py
index e5e90ca3..81381347 100755
--- a/mmgen/main_addrimport.py
+++ b/mmgen/main_addrimport.py
@@ -29,7 +29,7 @@ from mmgen.obj import TwLabel
 # In batch mode, bitcoind just rescans each address separately anyway, so make
 # --batch and --rescan incompatible.
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc': """Import addresses (both {pnm} and non-{pnm}) into an {pnm}
                      tracking wallet""".format(pnm=g.proj_name),
 	'usage':'[opts] [mmgen address file]',
diff --git a/mmgen/main_passgen.py b/mmgen/main_passgen.py
index c0e6a8bd..7c7897b1 100755
--- a/mmgen/main_passgen.py
+++ b/mmgen/main_passgen.py
@@ -32,7 +32,7 @@ dfl_len = {
 	'b32': PasswordList.pw_info['b32']['dfl_len']
 }
 
-def opts_data(): return {
+opts_data = lambda: {
 	'sets': [('print_checksum',True,'quiet',True)],
 	'desc': """Generate a range or list of passwords from an {pnm} wallet,
                   mnemonic, seed or brainwallet for the given ID string""".format(pnm=g.proj_name),
diff --git a/mmgen/main_tool.py b/mmgen/main_tool.py
index 8f847c8b..d5c930d0 100755
--- a/mmgen/main_tool.py
+++ b/mmgen/main_tool.py
@@ -24,7 +24,7 @@ mmgen-tool:  Perform various MMGen- and Bitcoin-related operations.
 from mmgen.common import *
 import mmgen.tool as tool
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc':    'Perform various {pnm}- and Bitcoin-related operations'.format(pnm=g.proj_name),
 	'usage':   '[opts] <command> <command args>',
 	'options': """
diff --git a/mmgen/main_txbump.py b/mmgen/main_txbump.py
index 6517b1b7..d11ce625 100755
--- a/mmgen/main_txbump.py
+++ b/mmgen/main_txbump.py
@@ -24,7 +24,7 @@ mmgen-txbump: Increase the fee on a replaceable (replace-by-fee) MMGen
 from mmgen.txcreate import *
 from mmgen.txsign import *
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc': 'Increase the fee on a replaceable (RBF) {g.proj_name} transaction, creating a new transaction, and optionally sign and send the new transaction'.format(g=g),
 	'usage':   '[opts] <{g.proj_name} TX file> [seed source] ...'.format(g=g),
 	'sets': ( ('yes', True, 'quiet', True), ),
diff --git a/mmgen/main_txcreate.py b/mmgen/main_txcreate.py
index b7530a4e..f15b21a9 100755
--- a/mmgen/main_txcreate.py
+++ b/mmgen/main_txcreate.py
@@ -23,7 +23,7 @@ mmgen-txcreate: Create a Bitcoin transaction to and from MMGen- or non-MMGen
 
 from mmgen.txcreate import *
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc': 'Create a transaction with outputs to specified Bitcoin or {g.proj_name} addresses'.format(g=g),
 	'usage':   '[opts]  <addr,amt> ... [change addr] [addr file] ...',
 	'sets': ( ('yes', True, 'quiet', True), ),
diff --git a/mmgen/main_txdo.py b/mmgen/main_txdo.py
index 81c994a1..29a32a1a 100755
--- a/mmgen/main_txdo.py
+++ b/mmgen/main_txdo.py
@@ -23,7 +23,7 @@ mmgen-txdo: Create, sign and broadcast an online MMGen transaction
 from mmgen.txcreate import *
 from mmgen.txsign import *
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc': 'Create, sign and send an {g.proj_name} transaction'.format(g=g),
 	'usage':   '[opts]  <addr,amt> ... [change addr] [addr file] ... [seed source] ...',
 	'sets': ( ('yes', True, 'quiet', True), ),
@@ -89,7 +89,7 @@ do_license_msg()
 
 kal = get_keyaddrlist(opt)
 kl = get_keylist(opt)
-if kl and kal: kl.remove_dups(kal,key='wif')
+if kl and kal: kl.remove_dup_keys(kal)
 
 tx = txcreate(cmd_args,caller='txdo')
 txsign(opt,c,tx,seed_files,kl,kal)
diff --git a/mmgen/main_txsend.py b/mmgen/main_txsend.py
index b1ee2d6a..35a1778a 100755
--- a/mmgen/main_txsend.py
+++ b/mmgen/main_txsend.py
@@ -23,7 +23,7 @@ mmgen-txsend: Broadcast a transaction signed by 'mmgen-txsign' to the network
 from mmgen.common import *
 from mmgen.tx import *
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc':    'Send a Bitcoin transaction signed by {pnm}-txsign'.format(
 					pnm=g.proj_name.lower()),
 	'usage':   '[opts] <signed transaction file>',
diff --git a/mmgen/main_txsign.py b/mmgen/main_txsign.py
index ad2aad37..bd5c8c6e 100755
--- a/mmgen/main_txsign.py
+++ b/mmgen/main_txsign.py
@@ -23,7 +23,7 @@ mmgen-txsign: Sign a transaction generated by 'mmgen-txcreate'
 from mmgen.txsign import *
 
 # -w, --use-wallet-dat (keys from running bitcoind) removed: use bitcoin-cli walletdump instead
-def opts_data(): return {
+opts_data = lambda: {
 	'desc':    'Sign Bitcoin transactions generated by {pnl}-txcreate'.format(pnl=pnm.lower()),
 	'usage':   '[opts] <transaction file>... [seed source]...',
 	'sets': ( ('yes', True, 'quiet', True), ),
@@ -88,7 +88,7 @@ seed_files = get_seed_files(opt,infiles)
 
 kal        = get_keyaddrlist(opt)
 kl         = get_keylist(opt)
-if kl and kal: kl.remove_dups(kal,key='wif')
+if kl and kal: kl.remove_dup_keys(kal)
 
 tx_num_str = ''
 for tx_num,tx_file in enumerate(tx_files,1):
diff --git a/mmgen/main_wallet.py b/mmgen/main_wallet.py
index 2731ca90..8c739de1 100755
--- a/mmgen/main_wallet.py
+++ b/mmgen/main_wallet.py
@@ -55,7 +55,7 @@ elif invoked_as == 'passchg':
 else:
 	die(1,"'%s': unrecognized invocation" % g.prog_name)
 
-def opts_data(): return {
+opts_data = lambda: {
 # Can't use: share/Opts doesn't know anything about fmt codes
 #	'sets': [('hidden_incog_output_params',bool,'out_fmt','hi')],
 	'desc': desc.format(pnm=g.proj_name),
diff --git a/mmgen/obj.py b/mmgen/obj.py
index 22462970..cdf23da5 100755
--- a/mmgen/obj.py
+++ b/mmgen/obj.py
@@ -17,21 +17,26 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """
-obj.py:  MMGen native classes
+obj.py: MMGen native classes
 """
 
 import sys
 from decimal import *
 from mmgen.color import *
-lvl = 0
+
+def is_mmgen_seed_id(s): return SeedID(sid=s,on_fail='silent')
+def is_mmgen_idx(s):     return AddrIdx(s,on_fail='silent')
+def is_mmgen_id(s):      return MMGenID(s,on_fail='silent')
+def is_btc_addr(s):      return BTCAddr(s,on_fail='silent')
+def is_addrlist_id(s):   return AddrListID(s,on_fail='silent')
+def is_tw_label(s):      return TwLabel(s,on_fail='silent')
+def is_wif(s):           return WifKey(s,on_fail='silent')
 
 class MMGenObject(object):
 
-	# Pretty-print any object of type MMGenObject, recursing into sub-objects - WIP
-# 	def pmsg(self):  sys.stderr.write(self.pformat()+'\n')
-# 	def pdie(self):  sys.stderr.write(self.pformat()+'\n'); sys.exit(0)
-	def pmsg(self):  print(self.pformat())
-	def pdie(self):  print(self.pformat()); sys.exit(0)
+	# Pretty-print any object subclassed from MMGenObject, recursing into sub-objects - WIP
+	def pmsg(self): print(self.pformat())
+	def pdie(self): print(self.pformat()); sys.exit(0)
 	def pformat(self,lvl=0):
 		from decimal import Decimal
 		scalars = (str,unicode,int,float,Decimal)
@@ -68,8 +73,8 @@ class MMGenObject(object):
 
 # 		print type(self)
 # 		print dir(self)
-# 		print self.__dict__ # *attributes* of object
-# 		print self.__dict__.keys() # *attributes* of object
+# 		print self.__dict__
+# 		print self.__dict__.keys()
 # 		print self.keys()
 
 		out = [u'<{}>{}\n'.format(type(self).__name__,' '+repr(self) if isScalar(self) else '')]
@@ -96,39 +101,73 @@ class MMGenObject(object):
 class MMGenList(list,MMGenObject): pass
 class MMGenDict(dict,MMGenObject): pass
 
-# Descriptor: https://docs.python.org/2/howto/descriptor.html
-class MMGenListItemAttr(object):
-	def __init__(self,name,dtype):
+class MMGenImmutableAttr(object): # Descriptor
+
+	typeconv = False
+	builtin_typeconv = False
+
+	def __init__(self,name,dtype,typeconv=None,builtin_typeconv=None):
+		if typeconv is not None:
+			assert typeconv in (True,False)
+			self.typeconv = typeconv
+		if builtin_typeconv is not None:
+			assert builtin_typeconv
+			self.builtin_typeconv = builtin_typeconv
+			self.typeconv = False # override
 		self.name = name
 		self.dtype = dtype
+
 	def __get__(self,instance,owner):
 		return instance.__dict__[self.name]
+
+	# forbid all reassignment
+	def chk_ok_set_attr(self,instance):
+		if hasattr(instance,self.name):
+			m = "Attribute '{}' of {} instance cannot be reassigned"
+			raise AttributeError(m.format(self.name,type(instance)))
+
 	def __set__(self,instance,value):
-#		if self.name == 'mmid': print repr(instance), repr(value) # DEBUG
-		instance.__dict__[self.name] = globals()[self.dtype](value)
+		self.chk_ok_set_attr(instance)
+		if self.typeconv:   # convert type
+			instance.__dict__[self.name] = globals()[self.dtype](value)
+		elif self.builtin_typeconv:
+			instance.__dict__[self.name] = self.dtype(value)
+		else:               # check type
+			if type(value) != self.dtype:
+				m = "Attribute '{}' of {} instance must of type {}"
+				raise TypeError(m.format(self.name,type(instance),self.dtype))
+			instance.__dict__[self.name] = value
+
 	def __delete__(self,instance):
-		del instance.__dict__[self.name]
+		if self.name in instance.delete_ok:
+			if self.name in instance.__dict__:
+				del instance.__dict__[self.name]
+		else:
+			m = "Atribute '{}' of {} instance cannot be deleted"
+			raise AttributeError(m.format(self.name,type(instance)))
+
+class MMGenListItemAttr(MMGenImmutableAttr):
+
+	typeconv = True
+	builtin_typeconv = False
+
+	# return None if attribute doesn't exist
+	def __get__(self,instance,owner):
+		try: return instance.__dict__[self.name]
+		except: return None
+
+	# allow reassignment if value is None or attr in reassign_ok list
+	def chk_ok_set_attr(self,instance):
+		if hasattr(instance,self.name) and not (
+			getattr(instance,self.name) == None or self.name in instance.reassign_ok
+		):
+			m = "Attribute '{}' of {} instance cannot be reassigned"
+			raise AttributeError(m.format(self.name,type(instance)))
 
 class MMGenListItem(MMGenObject):
 
-	addr  = MMGenListItemAttr('addr','BTCAddr')
-	amt   = MMGenListItemAttr('amt','BTCAmt')
-	mmid  = MMGenListItemAttr('mmid','MMGenID')
-	label = MMGenListItemAttr('label','TwComment')
-
-	attrs = ()
-	attrs_priv = ()
-	attrs_reassign = 'label',
-
-	def attr_error(self,arg):
-		raise AttributeError, "'{}': invalid attribute for {}".format(arg,type(self).__name__)
-	def set_error(self,attr,val):
-		raise ValueError, \
-			"'{}': attribute '{}' in instance of class '{}' cannot be reassigned".format(
-				val,attr,type(self).__name__)
-
-	attrs_base = ('attrs','attrs_priv','attrs_reassign','attrs_base','attr_error','set_error',
-				'__dict__','pformat','pmsg','pdie')
+	reassign_ok = ()
+	delete_ok = ()
 
 	def __init__(self,*args,**kwargs):
 		if args:
@@ -137,40 +176,18 @@ class MMGenListItem(MMGenObject):
 			if kwargs[k] != None:
 				setattr(self,k,kwargs[k])
 
-	def __getattribute__(self,name):
-		ga = object.__getattribute__
-		if name in ga(self,'attrs') + ga(self,'attrs_priv') + ga(self,'attrs_base'):
-			try:
-				return ga(self,name)
-			except:
-				return None
-		else:
-			self.attr_error(name)
-
-	def __setattr__(self,name,val):
-		if name in (self.attrs + self.attrs_priv + self.attrs_base):
-			if getattr(self,name) == None or name in self.attrs_reassign:
-				object.__setattr__(self,name,val)
-			else:
-#				object.__setattr__(self,name,val) # DEBUG
-				self.set_error(name,val)
-		else:
-			self.attr_error(name)
-
-	def __delattr__(self,name):
-		if name in (self.attrs + self.attrs_priv + self.attrs_base):
-			try: # don't know why this is necessary
-				object.__delattr__(self,name)
-			except:
-				pass
-		else:
-			self.attr_error(name)
+	# prevent setting random attributes
+	def __setattr__(self,name,value):
+		if name not in type(self).__dict__:
+			m = "'{}': no such attribute in class {}"
+			raise AttributeError(m.format(name,type(self)))
+		return object.__setattr__(self,name,value)
 
 class InitErrors(object):
 
 	@staticmethod
 	def arg_chk(cls,on_fail):
-		assert on_fail in ('die','return','silent','raise'),"arg_chk in class %s" % cls.__name__
+		assert on_fail in ('die','return','silent','raise'),'arg_chk in class {}'.format(cls.__name__)
 
 	@staticmethod
 	def init_fail(m,on_fail,silent=False):
@@ -527,13 +544,83 @@ class WifKey(str,Hilite,InitErrors):
 	desc = 'WIF key'
 	def __new__(cls,s,on_fail='die',errmsg=None):
 		cls.arg_chk(cls,on_fail)
-		from mmgen.tx import is_wif
-		if is_wif(s):
+		from mmgen.bitcoin import wif2hex
+		if wif2hex(s):
 			me = str.__new__(cls,s)
 			return me
 		m = errmsg or "'{}': invalid value for {}".format(s,cls.desc)
 		return cls.init_fail(m,on_fail)
 
+class HexStr(str,Hilite,InitErrors):
+	color = 'red'
+	trunc_ok = False
+	def __new__(cls,s,on_fail='die',case='lower'):
+		assert case in ('upper','lower')
+		cls.arg_chk(cls,on_fail)
+		from string import hexdigits
+		if set(s) <= set(getattr(hexdigits,case)()) and not len(s) % 2:
+			return str.__new__(cls,s)
+		m = "'{}': value cannot be converted to {}".format(s,cls.__name__)
+		return cls.init_fail(m,on_fail)
+
+class PubKey(HexStr,MMGenObject):
+	def __new__(cls,s,compressed,on_fail='die'):
+		assert type(compressed) == bool
+		me = HexStr.__new__(cls,s,case='lower')
+		me.compressed = compressed
+		return me
+
+class PrivKey(str,Hilite,InitErrors,MMGenObject):
+
+	color = 'red'
+	width = 64
+	trunc_ok = False
+
+	compressed = MMGenImmutableAttr('compressed',bool)
+	wif        = MMGenImmutableAttr('wif',WifKey)
+
+	def __new__(*args,**kwargs): # initialize with (priv_bin,compressed), WIF or self
+		cls = args[0]
+		assert set(kwargs) <= set(['on_fail','wif'])
+		on_fail = kwargs['on_fail'] if 'on_fail' in kwargs else 'die'
+		cls.arg_chk(cls,on_fail)
+
+		if len(args) == 2:
+			assert type(args[1]) == cls
+			return args[1]
+
+		if 'wif' in kwargs:
+			assert len(args) == 1
+			try:
+				from mmgen.bitcoin import wif2hex,wif_is_compressed # TODO: move these here
+				wif = WifKey(kwargs['wif'])
+				me = str.__new__(cls,wif2hex(wif))
+				me.compressed = wif_is_compressed(wif)
+				me.wif = wif
+				return me
+			except:
+				fs = "Value '{}' cannot be converted to WIF key"
+				errmsg = fs.format(kwargs['wif'])
+				return cls.init_fail(errmsg,on_fail)
+
+		cls,s,compressed = args
+
+		try:
+			from binascii import hexlify
+			assert len(s) == cls.width / 2
+			me = str.__new__(cls,hexlify(s))
+			me.compressed = compressed
+			me.wif = me.towif()
+			return me
+		except:
+			fs = "Key={}\nCompressed={}\nValue pair cannot be converted to {}"
+			errmsg = fs.format(repr(s),compressed,cls.__name__)
+			return cls.init_fail(errmsg,on_fail)
+
+	def towif(self):
+		from mmgen.bitcoin import hex2wif
+		return WifKey(hex2wif(self,compressed=self.compressed))
+
 class MMGenAddrType(str,Hilite,InitErrors):
 	width = 1
 	trunc_ok = False
diff --git a/mmgen/share/Opts.py b/mmgen/share/Opts.py
index ff9245a2..b8178456 100755
--- a/mmgen/share/Opts.py
+++ b/mmgen/share/Opts.py
@@ -24,7 +24,7 @@ import sys, getopt
 # from mmgen.util import mdie,die,pdie,pmsg # DEBUG
 
 def usage(opts_data):
-	print 'USAGE: %s %s' % (opts_data['prog_name'], opts_data['usage'])
+	print('USAGE: %s %s' % (opts_data['prog_name'], opts_data['usage']))
 	sys.exit(2)
 
 def print_help_and_exit(opts_data,longhelp=False):
@@ -36,9 +36,9 @@ def print_help_and_exit(opts_data,longhelp=False):
 	hdr = ('OPTIONS:','  LONG OPTIONS:')[longhelp]
 	ls = ('  ','')[longhelp]
 	es = ('','    ')[longhelp]
-	out += '{ls}{}\n{ls}{es}{}\n'.format(hdr,('\n'+ls).join(od_opts),ls=ls,es=es)
+	out += '{ls}{}\n{ls}{es}{}'.format(hdr,('\n'+ls).join(od_opts),ls=ls,es=es)
 	if 'notes' in opts_data and not longhelp:
-		out += '  ' + '\n  '.join(opts_data['notes'][1:-1].splitlines())
+		out += '\n  ' + '\n  '.join(opts_data['notes'][1:-1].splitlines())
 	print(out)
 	sys.exit(0)
 
@@ -51,7 +51,7 @@ def process_opts(argv,opts_data,short_opts,long_opts,defer_help=False):
 	so_str = short_opts.replace('-:','').replace('-','')
 	try: cl_opts,args = getopt.getopt(argv[1:], so_str, long_opts)
 	except getopt.GetoptError as err:
-		print str(err); sys.exit(2)
+		print(str(err)); sys.exit(2)
 
 	sopts_list = ':_'.join(['_'.join(list(i)) for i in short_opts.split(':')]).split('_')
 	opts,do_help = {},False
diff --git a/mmgen/tw.py b/mmgen/tw.py
index 00407e25..e98713a2 100755
--- a/mmgen/tw.py
+++ b/mmgen/tw.py
@@ -38,11 +38,19 @@ class MMGenTrackingWallet(MMGenObject):
 
 	class MMGenTwOutputList(list,MMGenObject): pass
 
-	class MMGenTwOutput(MMGenListItem):
+	class MMGenTwUnspentOutput(MMGenListItem):
+	#	attrs = 'txid','vout','amt','label','twmmid','addr','confs','scriptPubKey','days','skip'
+		reassign_ok = 'label','skip'
+		txid     = MMGenListItemAttr('txid','BitcoinTxID')
+		vout     = MMGenListItemAttr('vout',int,typeconv=False),
+		amt      = MMGenListItemAttr('amt','BTCAmt'),
+		label    = MMGenListItemAttr('label','TwComment'),
 		twmmid = MMGenListItemAttr('twmmid','TwMMGenID')
-		txid   = MMGenListItemAttr('txid','BitcoinTxID')
-		attrs_reassign = 'label','skip'
-		attrs = 'txid','vout','amt','label','twmmid','addr','confs','scriptPubKey','days','skip'
+		addr     = MMGenListItemAttr('addr','BTCAddr'),
+		confs    = MMGenListItemAttr('confs',int,typeconv=False),
+		scriptPubKey = MMGenListItemAttr('scriptPubKey','HexStr')
+		days    = MMGenListItemAttr('days',int,typeconv=False),
+		skip    = MMGenListItemAttr('skip',bool,typeconv=False),
 
 	wmsg = {
 	'no_spendable_outputs': """
@@ -87,12 +95,12 @@ watch-only wallet using '{}-addrimport' and then re-run this program.
 					'twmmid': l.mmid,
 					'label':  l.comment,
 					'days':   int(o['confirmations'] * g.mins_per_block / (60*24)),
-					'amt':    o['amount'], # TODO
-					'addr':   o['address'],
+					'amt':    BTCAmt(o['amount']), # TODO
+					'addr':   BTCAddr(o['address']), # TODO
 					'confs':  o['confirmations']
 				})
 				mm_rpc.append(o)
-		self.unspent = self.MMGenTwOutputList([self.MMGenTwOutput(**dict([(k,v) for k,v in o.items() if k in self.MMGenTwOutput.attrs])) for o in mm_rpc])
+		self.unspent = self.MMGenTwOutputList([self.MMGenTwUnspentOutput(**dict([(k,v) for k,v in o.items() if k in self.MMGenTwUnspentOutput.__dict__])) for o in mm_rpc])
 		for u in self.unspent:
 			if u.label == None: u.label = ''
 		if not self.unspent:
diff --git a/mmgen/tx.py b/mmgen/tx.py
index de83d2c0..9b85df46 100755
--- a/mmgen/tx.py
+++ b/mmgen/tx.py
@@ -26,18 +26,6 @@ from binascii import unhexlify
 from mmgen.common import *
 from mmgen.obj import *
 
-def is_mmgen_seed_id(s): return SeedID(sid=s,on_fail='silent')
-def is_mmgen_idx(s):     return AddrIdx(s,on_fail='silent')
-def is_mmgen_id(s):      return MMGenID(s,on_fail='silent')
-def is_btc_addr(s):      return BTCAddr(s,on_fail='silent')
-def is_addrlist_id(s):   return AddrListID(s,on_fail='silent')
-def is_tw_label(s):      return TwLabel(s,on_fail='silent')
-
-def is_wif(s):
-	if s == '': return False
-	from mmgen.bitcoin import wif2hex
-	return bool(wif2hex(s))
-
 def segwit_is_active(exit_on_error=False):
 	d = bitcoin_connection().getblockchaininfo()
 	if d['chain'] == 'regtest':
@@ -125,6 +113,19 @@ class DeserializedTX(OrderedDict,MMGenObject): # need to add MMGen types
 		keys = 'txid','version','lock_time','witness_size','num_txins','txins','num_txouts','txouts'
 		return OrderedDict.__init__(self, ((k,d[k]) for k in keys))
 
+txio_attrs = {
+	'reassign_ok': ('label',),
+	'delete_ok':   ('have_wif',),
+	'vout':  MMGenListItemAttr('vout',int,typeconv=False),
+	'amt':   MMGenListItemAttr('amt','BTCAmt'),
+	'label': MMGenListItemAttr('label','TwComment'),
+	'mmid':  MMGenListItemAttr('mmid','MMGenID'),
+	'addr':  MMGenListItemAttr('addr','BTCAddr'),
+	'confs': MMGenListItemAttr('confs',int,builtin_typeconv=True), # long confs found in the wild, so convert
+	'txid':  MMGenListItemAttr('txid','BitcoinTxID'),
+	'have_wif': MMGenListItemAttr('have_wif',bool,typeconv=False)
+}
+
 class MMGenTX(MMGenObject):
 	ext      = 'rawtx'
 	raw_ext  = 'rawtx'
@@ -133,17 +134,13 @@ class MMGenTX(MMGenObject):
 	desc = 'transaction'
 
 	class MMGenTxInput(MMGenListItem):
-		attrs = 'txid','vout','amt','label','mmid','addr','confs','scriptPubKey','have_wif','sequence'
-		txid = MMGenListItemAttr('txid','BitcoinTxID')
+		for k in txio_attrs: locals()[k] = txio_attrs[k] # in lieu of inheritance
 		scriptPubKey = MMGenListItemAttr('scriptPubKey','HexStr')
+		sequence = MMGenListItemAttr('sequence',int,typeconv=False)
 
 	class MMGenTxOutput(MMGenListItem):
-		attrs = 'txid','vout','amt','label','mmid','addr','have_wif','is_chg'
-
-	class MMGenTxInputOldFmt(MMGenListItem):  # for converting old tx files only
-		tr = {'amount':'amt', 'address':'addr', 'confirmations':'confs','comment':'label'}
-		attrs = 'txid','vout','amt','label','mmid','addr','confs','scriptPubKey','wif'
-		attrs_priv = 'tr',
+		for k in txio_attrs: locals()[k] = txio_attrs[k]
+		is_chg = MMGenListItemAttr('is_chg',bool,typeconv=False)
 
 	class MMGenTxInputList(list,MMGenObject): pass
 	class MMGenTxOutputList(list,MMGenObject): pass
@@ -204,12 +201,6 @@ class MMGenTX(MMGenObject):
 				e.mmid,f = d[e.addr]
 				if f: e.label = f
 
-#	def encode_io(self,desc):
-# 		tr = getattr((self.MMGenTxOutput,self.MMGenTxInput)[desc=='inputs'],'tr')
-# 		tr_rev = dict([(v,k) for k,v in tr.items()])
-# 		return [dict([(tr_rev[e] if e in tr_rev else e,getattr(d,e)) for e in d.__dict__])
-# 					for d in getattr(self,desc)]
-#
 	def create_raw(self,c):
 		i = [{'txid':e.txid,'vout':e.vout} for e in self.inputs]
 		if self.inputs[0].sequence:
@@ -372,11 +363,6 @@ class MMGenTX(MMGenObject):
 			tx_fee = my_raw_input('Enter transaction fee: ')
 			desc = 'User-selected'
 
-	# inputs methods
-	def list_wifs(self,desc,mmaddrs_only=False):
-		return [e.wif for e in getattr(self,desc) if e.mmid] if mmaddrs_only \
-			else [e.wif for e in getattr(self,desc)]
-
 	def delete_attrs(self,desc,attr):
 		for e in getattr(self,desc):
 			if hasattr(e,attr): delattr(e,attr)
@@ -386,20 +372,23 @@ class MMGenTX(MMGenObject):
 			(self.MMGenTxOutput,self.MMGenTxOutputList),
 			(self.MMGenTxInput,self.MMGenTxInputList)
 		)[desc=='inputs']
-		return il([io(**dict([(k,d[k]) for k in io.attrs
+		return il([io(**dict([(k,d[k]) for k in io.__dict__
 					if k in d and d[k] not in ('',None)])) for d in data])
 
 	def decode_io_oldfmt(self,data):
-		io = self.MMGenTxInputOldFmt
-		tr_rev = dict([(v,k) for k,v in io.tr.items()])
-		copy_keys = [tr_rev[k] if k in tr_rev else k for k in io.attrs]
-		return [io(**dict([(io.tr[k] if k in io.tr else k,d[k])
-					for k in copy_keys if k in d and d[k] != ''])) for d in data]
+		tr = {'amount':'amt', 'address':'addr', 'confirmations':'confs','comment':'label'}
+		tr_rev = dict([(v,k) for k,v in tr.items()])
+		copy_keys = [tr_rev[k] if k in tr_rev else k for k in self.MMGenTxInput.__dict__]
+		ret = MMGenList(self.MMGenTxInput(**dict([(tr[k] if k in tr else k,d[k])
+					for k in copy_keys if k in d and d[k] != ''])) for d in data)
+		for i in ret: i.sequence = int('0xffffffff',16)
+		return ret
 
+	# inputs methods
 	def copy_inputs_from_tw(self,tw_unspent_data):
 		txi,self.inputs = self.MMGenTxInput,self.MMGenTxInputList()
 		for d in tw_unspent_data:
-			t = txi(**dict([(attr,getattr(d,attr)) for attr in d.__dict__ if attr in txi.attrs]))
+			t = txi(**dict([(attr,getattr(d,attr)) for attr in d.__dict__ if attr in txi.__dict__]))
 			if d.twmmid.type == 'mmgen': t.mmid = d.twmmid # twmmid -> mmid
 			self.inputs.append(t)
 
@@ -443,37 +432,35 @@ class MMGenTX(MMGenObject):
 	def get_non_mmaddrs(self,desc):
 		return list(set(i.addr for i in getattr(self,desc) if not i.mmid))
 
-	# return true or false, don't exit
+	# return true or false; don't exit
 	def sign(self,c,tx_num_str,keys):
 
 		self.die_if_incorrect_chain()
 
-		if g.coin == 'BCH' and self.has_segwit_inputs():
-			die(2,yellow("Segwit inputs cannot be spent on BCH chain!"))
+		if g.coin == 'BCH' and (self.has_segwit_inputs() or self.has_segwit_outputs()):
+			die(2,yellow("Segwit inputs cannot be spent or spent to on the BCH chain!"))
 
-		if not keys:
-			msg('No keys. Cannot sign!')
-			return False
+		qmsg('Passing {} key{} to bitcoind'.format(len(keys),suf(keys,'s')))
 
-		qmsg('Passing %s key%s to bitcoind' % (len(keys),suf(keys,'s')))
+		if self.has_segwit_inputs():
+			from mmgen.addr import KeyGenerator,AddrGenerator
+			kg = KeyGenerator()
+			ag = AddrGenerator('segwit')
+			keydict = MMGenDict([(d.addr,d.sec) for d in keys])
 
 		sig_data = []
 		for d in self.inputs:
 			e = dict([(k,getattr(d,k)) for k in ('txid','vout','scriptPubKey','amt')])
 			e['amount'] = e['amt']
 			del e['amt']
-			wif = keys[d.addr]
 			if d.mmid and d.mmid.mmtype == 'S':
-				from mmgen.bitcoin import pubhex2redeem_script
-				from mmgen.addr import keygen_wif2pubhex,keygen_selector
-				pubhex = keygen_wif2pubhex(wif,keygen_selector())
-				e['redeemScript'] = pubhex2redeem_script(pubhex)
+				e['redeemScript'] = ag.to_segwit_redeem_script(kg.to_pubhex(keydict[d.addr]))
 			sig_data.append(e)
 
-		from mmgen.bitcoin import hash256
 		msg_r('Signing transaction{}...'.format(tx_num_str))
 		ht = ('ALL','ALL|FORKID')[g.coin=='BCH'] # sighashtype defaults to 'ALL'
-		ret = c.signrawtransaction(self.hex,sig_data,keys.values(),ht,on_fail='return')
+		wifs = [d.sec.wif for d in keys]
+		ret = c.signrawtransaction(self.hex,sig_data,wifs,ht,on_fail='return')
 
 		from mmgen.rpc import rpc_error,rpc_errmsg
 		if rpc_error(ret):
@@ -586,12 +573,7 @@ class MMGenTX(MMGenObject):
 			confirm_or_exit(m1,m2,m3)
 
 		msg('Sending transaction')
-		if bogus_send:
-			ret = 'deadbeef' * 8
-			m = 'BOGUS transaction NOT sent: %s'
-		else:
-			ret = c.sendrawtransaction(self.hex,on_fail='return')
-			m = 'Transaction sent: %s'
+		ret = None if bogus_send else c.sendrawtransaction(self.hex,on_fail='return')
 
 		from mmgen.rpc import rpc_error,rpc_errmsg
 		if rpc_error(ret):
@@ -608,10 +590,13 @@ class MMGenTX(MMGenObject):
 			msg(red('Send of MMGen transaction {} failed'.format(self.txid)))
 			return False
 		else:
-			if not bogus_send:
+			if bogus_send:
+				m = 'BOGUS transaction NOT sent: {}'
+			else:
 				assert ret == self.btc_txid, 'txid mismatch (after sending)'
+				m = 'Transaction sent: {}'
 			self.desc = 'sent transaction'
-			msg(m % self.btc_txid.hl())
+			msg(m.format(self.btc_txid.hl()))
 			self.add_timestamp()
 			self.add_blockcount(c)
 			return True
@@ -666,7 +651,6 @@ class MMGenTX(MMGenObject):
 		self.inputs[0].sequence = g.max_int - 2
 
 	def format_view(self,terse=False):
-#		self.pdie()
 		try:
 			blockcount = bitcoin_connection().getblockcount()
 		except:
diff --git a/mmgen/txsign.py b/mmgen/txsign.py
index 9f7abeab..be7327cc 100755
--- a/mmgen/txsign.py
+++ b/mmgen/txsign.py
@@ -86,19 +86,20 @@ def get_seed_for_seed_id(sid,infiles,saved_seeds):
 		saved_seeds[ss.seed.sid] = ss.seed
 		if ss.seed.sid == sid: return ss.seed
 
-def generate_keys_for_mmgen_addrs(mmgen_addrs,infiles,saved_seeds):
-	sids = set(i.sid for i in mmgen_addrs)
+def generate_kals_for_mmgen_addrs(need_keys,infiles,saved_seeds):
+	mmids = [e.mmid for e in need_keys]
+	sids = set(i.sid for i in mmids)
 	vmsg('Need seed%s: %s' % (suf(sids,'s'),' '.join(sids)))
-	d = AddrListList()
+	d = MMGenList()
 	from mmgen.addr import KeyAddrList
 	for sid in sids:
 		# Returns only if seed is found
 		seed = get_seed_for_seed_id(sid,infiles,saved_seeds)
 		for t in MMGenAddrType.mmtypes:
-			idx_list = [i.idx for i in mmgen_addrs if i.sid == sid and i.mmtype == t]
+			idx_list = [i.idx for i in mmids if i.sid == sid and i.mmtype == t]
 			if idx_list:
 				addr_idxs = AddrIdxList(idx_list=idx_list)
-				d += KeyAddrList(seed=seed,addr_idxs=addr_idxs,do_chksum=False,mmtype=MMGenAddrType(t)).flat_list()
+				d.append(KeyAddrList(seed=seed,addr_idxs=addr_idxs,do_chksum=False,mmtype=MMGenAddrType(t)))
 	return d
 
 def add_keys(tx,src,infiles=None,saved_seeds=None,keyaddr_list=None):
@@ -107,18 +108,20 @@ def add_keys(tx,src,infiles=None,saved_seeds=None,keyaddr_list=None):
 	desc,m1 = ('key-address file','From key-address file:') if keyaddr_list else \
 					('seed(s)','Generated from seed:')
 	qmsg('Checking {} -> {} address mappings for {} (from {})'.format(pnm,g.coin,src,desc))
-	d = keyaddr_list.flat_list() if keyaddr_list else \
-		generate_keys_for_mmgen_addrs([e.mmid for e in need_keys],infiles,saved_seeds)
+	d = MMGenList([keyaddr_list]) if keyaddr_list else \
+		generate_kals_for_mmgen_addrs(need_keys,infiles,saved_seeds)
 	new_keys = []
 	for e in need_keys:
-		for f in d:
-			if f.mmid == e.mmid:
-				if f.addr == e.addr:
-					e.have_wif = True
-					if src == 'inputs':
-						new_keys.append((f.addr,f.wif))
-				else:
-					die(3,wmsg['mapping_error'].format(m1,f.mmid,f.addr,'tx file:',e.mmid,e.addr))
+		for kal in d:
+			for f in kal.data:
+				mmid = '{}:{}'.format(kal.al_id,f.idx)
+				if mmid == e.mmid:
+					if f.addr == e.addr:
+						e.have_wif = True
+						if src == 'inputs':
+							new_keys.append(f)
+					else:
+						die(3,wmsg['mapping_error'].format(m1,mmid,f.addr,'tx file:',e.mmid,e.addr))
 	if new_keys:
 		vmsg('Added %s wif key%s from %s' % (len(new_keys),suf(new_keys,'s'),desc))
 	return new_keys
@@ -151,22 +154,22 @@ def get_keyaddrlist(opt):
 def get_keylist(opt):
 	if opt.keys_from_file:
 		l = get_lines_from_file(opt.keys_from_file,'key-address data',trim_comments=True)
-		ret = KeyAddrList(keylist=[m.split()[0] for m in l]) # accept bitcoind wallet dumps
-		ret.generate_addrs_from_keylist()
-		return ret
+		kal = KeyAddrList(keylist=[m.split()[0] for m in l]) # accept bitcoind wallet dumps
+		kal.generate_addrs_from_keys()
+		return kal
 	return None
 
 def txsign(opt,c,tx,seed_files,kl,kal,tx_num_str=''):
-	# Start
-	keys = []
-#	tx.pmsg()
+
+	keys = MMGenList() # list of AddrListEntry objects
 	non_mm_addrs = tx.get_non_mmaddrs('inputs')
+
 	if non_mm_addrs:
 		tmp = KeyAddrList(addrlist=non_mm_addrs,do_chksum=False)
 		tmp.add_wifs(kl)
-		m = tmp.list_missing('wif')
+		m = tmp.list_missing('sec')
 		if m: die(2,wmsg['missing_keys_error'].format(suf(m,'es'),'\n    '.join(m)))
-		keys += tmp.get_addr_wif_pairs()
+		keys += tmp.data
 
 	if opt.mmgen_keys_from_file:
 		keys += add_keys(tx,'inputs',keyaddr_list=kal)
@@ -175,6 +178,7 @@ def txsign(opt,c,tx,seed_files,kl,kal,tx_num_str=''):
 	keys += add_keys(tx,'inputs',seed_files,saved_seeds)
 	add_keys(tx,'outputs',seed_files,saved_seeds)
 
+	# this attr must not be written to file
 	tx.delete_attrs('inputs','have_wif')
 	tx.delete_attrs('outputs','have_wif')
 
@@ -182,7 +186,7 @@ def txsign(opt,c,tx,seed_files,kl,kal,tx_num_str=''):
 	if extra_sids:
 		msg('Unused Seed ID{}: {}'.format(suf(extra_sids,'s'),' '.join(extra_sids)))
 
-	if tx.sign(c,tx_num_str,dict(keys)):
+	if tx.sign(c,tx_num_str,keys):
 		return tx
 	else:
 		die(3,red('Transaction {}could not be signed.'.format(tx_num_str)))
diff --git a/scripts/compute-file-chksum.py b/scripts/compute-file-chksum.py
index 4a6c293c..d9776ca1 100755
--- a/scripts/compute-file-chksum.py
+++ b/scripts/compute-file-chksum.py
@@ -1,14 +1,18 @@
 #!/usr/bin/env python
 
+import sys,os
+repo_root = os.path.split(os.path.abspath(os.path.dirname(sys.argv[0])))[0]
+sys.path = [repo_root] + sys.path
+
 from mmgen.common import *
 
-opts_data = {
+opts_data = lambda: {
 	'desc': 'Compute checksum for a MMGen data file',
 	'usage':'[opts] infile',
 	'options': """
 -h, --help               Print this help message.
 -i, --include-first-line Include the first line of the file (you probably don't want this)
-""".strip()
+"""
 }
 
 cmd_args = opts.init(opts_data)
diff --git a/scripts/tx-old2new.py b/scripts/tx-old2new.py
index 254703c8..7abeb0ca 100755
--- a/scripts/tx-old2new.py
+++ b/scripts/tx-old2new.py
@@ -5,15 +5,9 @@ repo_root = os.path.split(os.path.abspath(os.path.dirname(sys.argv[0])))[0]
 sys.path = [repo_root] + sys.path
 
 from mmgen.common import *
-
-from mmgen.tool import *
 from mmgen.tx import *
-from mmgen.bitcoin import *
-from mmgen.obj import MMGenTXLabel
-from mmgen.seed import *
-from mmgen.term import do_pager
 
-help_data = {
+opts_data = lambda: {
 	'desc':    "Convert MMGen transaction file from old format to new format",
 	'usage':   "<tx file>",
 	'options': """
@@ -22,52 +16,42 @@ help_data = {
 """
 }
 
-import mmgen.opts
-cmd_args = opts.init(help_data)
+cmd_args = opts.init(opts_data)
 
 if len(cmd_args) != 1: opts.usage()
 def parse_tx_file(infile):
 
-	err_str,err_fmt = '','Invalid %s in transaction file'
+	err_fmt = 'Invalid {} in transaction file'
 	tx_data = get_lines_from_file(infile)
 
-	if len(tx_data) == 5:
-		metadata,tx_hex,inputs_data,outputs_data,comment = tx_data
-	elif len(tx_data) == 4:
-		metadata,tx_hex,inputs_data,outputs_data = tx_data
-		comment = ''
-	else:
+	try:
 		err_str = 'number of lines'
-
-	if not err_str:
-		if len(metadata.split()) != 3:
-			err_str = 'metadata'
-		else:
-			try: unhexlify(tx_hex)
-			except: err_str = 'hex data'
+		assert len(tx_data) in (4,5)
+		if len(tx_data) == 5:
+			metadata,tx_hex,inputs,outputs,comment = tx_data
+		elif len(tx_data) == 4:
+			metadata,tx_hex,inputs,outputs = tx_data
+			comment = ''
+		err_str = 'metadata'
+		assert len(metadata.split()) == 3
+		err_str = 'hex data'
+		unhexlify(tx_hex)
+		err_str = 'inputs data'
+		inputs = eval(inputs)
+		err_str = 'btc-to-mmgen address map data'
+		outputs = eval(outputs)
+		if comment:
+			from mmgen.bitcoin import b58decode
+			comment = b58decode(comment)
+			if comment == False:
+				err_str = 'encoded comment (not base58)'
 			else:
-				try: inputs_data = eval(inputs_data)
-				except: err_str = 'inputs data'
-				else:
-					try: outputs_data = eval(outputs_data)
-					except: err_str = 'btc-to-mmgen address map data'
-					else:
-						if comment:
-							from mmgen.bitcoin import b58decode
-							comment = b58decode(comment)
-							if comment == False:
-								err_str = 'encoded comment (not base58)'
-							else:
-								try:
-									comment = MMGenTXLabel(comment)
-								except:
-									err_str = 'comment'
-
-	if err_str:
-		msg(err_fmt % err_str)
-		sys.exit(2)
+				err_str = 'comment'
+				comment = MMGenTXLabel(comment)
+	except:
+		die(2,err_fmt.format(err_str))
 	else:
-		return metadata.split(),tx_hex,inputs_data,outputs_data,comment
+		return metadata.split(),tx_hex,inputs,outputs,comment
 
 def find_block_by_time(c,timestamp):
 	secs = decode_timestamp(timestamp)
@@ -95,15 +79,14 @@ def find_block_by_time(c,timestamp):
 
 tx = MMGenTX()
 
-[tx.txid,send_amt,tx.timestamp],tx.hex,inputs,b2m_map,tx.label = parse_tx_file(cmd_args[0])
+metadata,tx.hex,inputs,b2m_map,tx.label = parse_tx_file(cmd_args[0])
+tx.txid,send_amt,tx.timestamp = metadata
 tx.send_amt = Decimal(send_amt)
 
 g.testnet = False
 g.rpc_host = 'localhost'
 c = bitcoin_connection()
 
-# attrs = 'txid','vout','amt','comment','mmid','addr','wif'
-#pp_msg(inputs)
 for i in inputs:
 	if not 'mmid' in i and 'account' in i:
 		from mmgen.tw import parse_tw_acct_label
@@ -112,16 +95,14 @@ for i in inputs:
 			i['mmid'] = a.decode('utf8')
 			if b: i['comment'] = b.decode('utf8')
 
-#pp_msg(inputs)
 tx.inputs = tx.decode_io_oldfmt(inputs)
 
-if tx.check_signed(c):
+if tx.marked_signed(c):
 	msg('Transaction is signed')
 
 dec_tx = c.decoderawtransaction(tx.hex)
-tx.outputs = [MMGenTxOutput(addr=i['scriptPubKey']['addresses'][0],amt=i['value'])
-				for i in dec_tx['vout']]
-
+tx.outputs = MMGenList(MMGenTX.MMGenTxOutput(addr=i['scriptPubKey']['addresses'][0],amt=i['value'])
+				for i in dec_tx['vout'])
 for e in tx.outputs:
 	if e.addr in b2m_map:
 		f = b2m_map[e.addr]
@@ -132,9 +113,6 @@ for e in tx.outputs:
 			if e.addr == f.addr and f.mmid:
 				e.mmid = f.mmid
 				if f.label: e.label = f.label.decode('utf8')
-#for i in tx.inputs: print i
-#for i in tx.outputs: print i
-#die(1,'')
-tx.blockcount = find_block_by_time(c,tx.timestamp)
 
+tx.blockcount = find_block_by_time(c,tx.timestamp)
 tx.write_to_file(ask_tty=False)
diff --git a/test/gentest.py b/test/gentest.py
index 5334f36c..e731afc7 100755
--- a/test/gentest.py
+++ b/test/gentest.py
@@ -32,7 +32,7 @@ from mmgen.common import *
 from mmgen.bitcoin import hex2wif
 
 rounds = 100
-def opts_data(): return {
+opts_data = lambda: {
 	'desc': "Test address generation in various ways",
 	'usage':'[options] [spec] [rounds | dump file]',
 	'options': """
@@ -118,25 +118,27 @@ def match_error(sec,wif,a_addr,b_addr,a,b):
 mmtype = ('L','S')[bool(opt.segwit)]
 compressed = True
 
+from mmgen.addr import KeyGenerator,AddrGenerator
+from mmgen.obj import PrivKey
+ag = AddrGenerator(('p2pkh','segwit')[bool(opt.segwit)])
+
 if a and b:
 	m = "Comparing address generators '{}' and '{}'"
 	qmsg(green(m.format(g.key_generators[a-1],g.key_generators[b-1])))
-	from mmgen.addr import get_privhex2addr_f
-	gen_a = get_privhex2addr_f(generator=a)
-	gen_b = get_privhex2addr_f(generator=b)
 	last_t = time.time()
+	kg_a = KeyGenerator(a)
+	kg_b = KeyGenerator(b)
 
 	for i in range(rounds):
 		if time.time() - last_t >= 0.1:
 			qmsg_r('\rRound %s/%s ' % (i+1,rounds))
 			last_t = time.time()
-		sec = hexlify(os.urandom(32))
-		wif = hex2wif(sec,compressed=compressed)
-		a_addr = gen_a(sec,compressed,mmtype=mmtype)
-		b_addr = gen_b(sec,compressed,mmtype=mmtype)
-		vmsg('\nkey:  %s\naddr: %s\n' % (wif,a_addr))
+		sec = PrivKey(os.urandom(32),compressed)
+		a_addr = ag.to_addr(kg_a.to_pubhex(sec))
+		b_addr = ag.to_addr(kg_b.to_pubhex(sec))
+		vmsg('\nkey:  %s\naddr: %s\n' % (sec.wif,a_addr))
 		if a_addr != b_addr:
-			match_error(sec,wif,a_addr,b_addr,a,b)
+			match_error(sec,sec.wif,a_addr,b_addr,a,b)
 		if not opt.segwit:
 			compressed = not compressed
 	qmsg_r('\rRound %s/%s ' % (i+1,rounds))
@@ -145,23 +147,21 @@ if a and b:
 elif a and not fh:
 	m = "Testing speed of address generator '{}'"
 	qmsg(green(m.format(g.key_generators[a-1])))
-	from mmgen.addr import get_privhex2addr_f
-	gen = get_privhex2addr_f(generator=a)
 	from struct import pack,unpack
 	seed = os.urandom(28)
 	print 'Incrementing key with each round'
 	print 'Starting key:', hexlify(seed+pack('I',0))
 	import time
 	start = last_t = time.time()
+	kg = KeyGenerator(a)
 
 	for i in range(rounds):
 		if time.time() - last_t >= 0.1:
 			qmsg_r('\rRound %s/%s ' % (i+1,rounds))
 			last_t = time.time()
-		sec = hexlify(seed+pack('I',i))
-		wif = hex2wif(sec,compressed=compressed)
-		a_addr = gen(sec,compressed,mmtype=mmtype)
-		vmsg('\nkey:  %s\naddr: %s\n' % (wif,a_addr))
+		sec = PrivKey(seed+pack('I',i),compressed)
+		a_addr = ag.to_addr(kg.to_pubhex(sec))
+		vmsg('\nkey:  %s\naddr: %s\n' % (sec.wif,a_addr))
 		if not opt.segwit:
 			compressed = not compressed
 	qmsg_r('\rRound %s/%s ' % (i+1,rounds))
@@ -170,18 +170,15 @@ elif a and not fh:
 elif a and dump:
 	m = "Comparing output of address generator '{}' against wallet dump '{}'"
 	qmsg(green(m.format(g.key_generators[a-1],cmd_args[1])))
-	if a == 2:
-		qmsg("NOTE: for compressed addresses, 'python-ecdsa' generator will be used")
-	from mmgen.addr import get_privhex2addr_f
-	gen_a = get_privhex2addr_f(generator=a)
-	from mmgen.bitcoin import wif2hex
+	kg = KeyGenerator(a)
 	for n,[wif,a_addr] in enumerate(dump,1):
 		qmsg_r('\rKey %s/%s ' % (n,len(dump)))
-		sec = wif2hex(wif)
-		if sec == False:
+		try:
+			sec = PrivKey(wif=wif)
+		except:
 			die(2,'\nInvalid {}net WIF address in dump file: {}'.format(('main','test')[g.testnet],wif))
 		compressed = wif[0] != ('5','9')[g.testnet]
-		b_addr = gen_a(sec,compressed,'L')
+		b_addr = ag.to_addr(kg.to_pubhex(sec))
 		if a_addr != b_addr:
-			match_error(sec,wif,a_addr,b_addr,1 if compressed and a==2 else a,4)
+			match_error(sec,wif,a_addr,b_addr,3,a)
 	qmsg(green(('\n','')[bool(opt.verbose)] + 'OK'))
diff --git a/test/test.py b/test/test.py
index 8dbf7d5e..7dd12f49 100755
--- a/test/test.py
+++ b/test/test.py
@@ -100,7 +100,7 @@ if not any(e in ('--skip-deps','--resume','-S','-r') for e in sys.argv+shortopts
 		except: pass
 		os.symlink(dd,data_dir)
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc': 'Test suite for the MMGen suite',
 	'usage':'[options] [command(s) or metacommand(s)]',
 	'options': """
diff --git a/test/tooltest.py b/test/tooltest.py
index e111dd6a..3fb99b32 100755
--- a/test/tooltest.py
+++ b/test/tooltest.py
@@ -115,7 +115,7 @@ cfg = {
 	'addrfile_chk':  '6FEF 6FB9 7B13 5D91',
 }
 
-def opts_data(): return {
+opts_data = lambda: {
 	'desc': "Test suite for the 'mmgen-tool' utility",
 	'usage':'[options] [command]',
 	'options': """