mirror of
https://github.com/trezor/trezor-firmware.git
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147 lines
4.2 KiB
Python
147 lines
4.2 KiB
Python
# This file is part of the Trezor project.
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#
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# Copyright (C) 2012-2019 SatoshiLabs and contributors
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#
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# This library is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License version 3
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# as published by the Free Software Foundation.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the License along with this library.
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# If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
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import hashlib
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import hmac
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import struct
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from copy import copy
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import ecdsa
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from ecdsa.curves import SECP256k1
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from ecdsa.ellipticcurve import INFINITY, Point
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from ecdsa.util import number_to_string, string_to_number
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from trezorlib import messages, tools
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def point_to_pubkey(point):
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order = SECP256k1.order
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x_str = number_to_string(point.x(), order)
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y_str = number_to_string(point.y(), order)
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vk = x_str + y_str
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return struct.pack("B", (vk[63] & 1) + 2) + vk[0:32] # To compressed key
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def sec_to_public_pair(pubkey):
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"""Convert a public key in sec binary format to a public pair."""
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x = string_to_number(pubkey[1:33])
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sec0 = pubkey[:1]
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if sec0 not in (b"\2", b"\3"):
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raise ValueError("Compressed pubkey expected")
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def public_pair_for_x(generator, x, is_even):
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curve = generator.curve()
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p = curve.p()
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alpha = (pow(x, 3, p) + curve.a() * x + curve.b()) % p
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beta = ecdsa.numbertheory.square_root_mod_prime(alpha, p)
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if is_even == bool(beta & 1):
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return (x, p - beta)
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return (x, beta)
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return public_pair_for_x(
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ecdsa.ecdsa.generator_secp256k1, x, is_even=(sec0 == b"\2")
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)
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def fingerprint(pubkey):
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return string_to_number(tools.hash_160(pubkey)[:4])
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def get_address(public_node, address_type):
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return tools.public_key_to_bc_address(public_node.public_key, address_type)
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def public_ckd(public_node, n):
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if not isinstance(n, list):
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raise ValueError("Parameter must be a list")
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node = copy(public_node)
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for i in n:
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node = get_subnode(node, i)
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return node
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def get_subnode(node, i):
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# Public Child key derivation (CKD) algorithm of BIP32
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i_as_bytes = struct.pack(">L", i)
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if i & tools.HARDENED_FLAG:
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raise ValueError("Prime derivation not supported")
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# Public derivation
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data = node.public_key + i_as_bytes
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I64 = hmac.HMAC(key=node.chain_code, msg=data, digestmod=hashlib.sha512).digest()
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I_left_as_exponent = string_to_number(I64[:32])
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# BIP32 magic converts old public key to new public point
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x, y = sec_to_public_pair(node.public_key)
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point = I_left_as_exponent * SECP256k1.generator + Point(
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SECP256k1.curve, x, y, SECP256k1.order
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)
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if point == INFINITY:
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raise ValueError("Point cannot be INFINITY")
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return messages.HDNodeType(
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depth=node.depth + 1,
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child_num=i,
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chain_code=I64[32:],
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fingerprint=fingerprint(node.public_key),
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# Convert public point to compressed public key
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public_key=point_to_pubkey(point),
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)
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def serialize(node, version=0x0488B21E):
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s = b""
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s += struct.pack(">I", version)
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s += struct.pack(">B", node.depth)
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s += struct.pack(">I", node.fingerprint)
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s += struct.pack(">I", node.child_num)
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s += node.chain_code
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if node.private_key:
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s += b"\x00" + node.private_key
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else:
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s += node.public_key
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s += tools.btc_hash(s)[:4]
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return tools.b58encode(s)
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def deserialize(xpub):
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data = tools.b58decode(xpub, None)
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if tools.btc_hash(data[:-4])[:4] != data[-4:]:
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raise ValueError("Checksum failed")
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node = messages.HDNodeType(
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depth=struct.unpack(">B", data[4:5])[0],
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fingerprint=struct.unpack(">I", data[5:9])[0],
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child_num=struct.unpack(">I", data[9:13])[0],
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chain_code=data[13:45],
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public_key=None,
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)
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key = data[45:-4]
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if key[0] == 0:
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node.private_key = key[1:]
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else:
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node.public_key = key
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return node
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