mirror of
https://github.com/bigchaindb/bigchaindb.git
synced 2024-10-13 13:34:05 +00:00
473 lines
19 KiB
Python
473 lines
19 KiB
Python
from copy import deepcopy
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from functools import reduce
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from operator import and_
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from uuid import uuid4
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from cryptoconditions import (
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Fulfillment as CCFulfillment,
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ThresholdSha256Fulfillment,
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Ed25519Fulfillment,
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)
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from cryptoconditions.exceptions import ParsingError
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# TODO: Eventually remove all coupling from the core BigchainDB code base, as this module will life separately.
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from bigchaindb_common.crypto import (
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SigningKey,
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hash_data,
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)
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from bigchaindb_common.exceptions import (
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KeypairMismatchException,
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)
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from bigchaindb_common.util import (
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serialize,
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gen_timestamp,
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)
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class Fulfillment(object):
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def __init__(self, fulfillment, owners_before=None, fid=0, tx_input=None):
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"""Create a new fulfillment
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Args:
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# TODO: Write a description here
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owners_before (Optional(list)): base58 encoded public key of the owners of the asset before this
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transaction.
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"""
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self.fid = fid
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# TODO: Check if `fulfillment` corresponds to `owners_before`, otherwise fail
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self.fulfillment = fulfillment
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if tx_input is not None and not isinstance(tx_input, TransactionLink):
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raise TypeError('`tx_input` must be a TransactionLink instance')
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else:
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self.tx_input = tx_input
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if not isinstance(owners_before, list):
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raise TypeError('`owners_before` must be a list instance')
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else:
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self.owners_before = owners_before
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def to_dict(self):
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try:
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# When we have signed the fulfillment, this will work
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fulfillment = self.fulfillment.serialize_uri()
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except TypeError:
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fulfillment = None
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try:
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# NOTE: `self.tx_input` can be `None` and that's fine
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tx_input = self.tx_input.to_dict()
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except AttributeError:
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tx_input = None
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return {
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'owners_before': self.owners_before,
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'input': tx_input,
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'fulfillment': fulfillment,
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'details': self.fulfillment.to_dict(),
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'fid': self.fid,
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}
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@classmethod
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def gen_default(cls, owners_after, fid=0):
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"""Creates default fulfillments for transactions, depending on how many `owners_after` are supplied.
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"""
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if not isinstance(owners_after, list):
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raise TypeError('`owners_after` must be a list instance')
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else:
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owners_after_count = len(owners_after)
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if owners_after_count == 0:
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# TODO: Replace this error with the logic for a hashlock condition
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raise NotImplementedError('Hashlock conditions are not implemented in BigchainDB yet')
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elif owners_after_count == 1:
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return cls(Ed25519Fulfillment(public_key=owners_after[0]), owners_after, fid)
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else:
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threshold_ffill = cls(ThresholdSha256Fulfillment(threshold=len(owners_after)), owners_after, fid)
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for owner_after in owners_after:
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threshold_ffill.fulfillment.add_subfulfillment(Ed25519Fulfillment(public_key=owner_after))
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return threshold_ffill
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def gen_condition(self):
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return Condition(self.fulfillment.condition_uri, self.owners_before, self.fid)
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@classmethod
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def from_dict(cls, ffill):
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""" Serializes a BigchainDB 'jsonized' fulfillment back to a BigchainDB Fulfillment class.
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"""
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try:
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fulfillment = CCFulfillment.from_uri(ffill['fulfillment'])
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except TypeError:
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fulfillment = CCFulfillment.from_dict(ffill['details'])
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return cls(fulfillment, ffill['owners_before'], ffill['fid'], TransactionLink.from_dict(ffill['input']))
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class Condition(object):
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def __init__(self, condition_uri, owners_after=None, cid=0):
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# TODO: Add more description
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"""Create a new condition for a fulfillment
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Args
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owners_after (Optional(list)): base58 encoded public key of the owner of the digital asset after
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this transaction.
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"""
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self.cid = cid
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# TODO: Check if `condition_uri` corresponds to `owners_after`, otherwise fail
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self.condition_uri = condition_uri
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if not isinstance(owners_after, list):
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raise TypeError('`owners_after` must be a list instance')
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else:
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self.owners_after = owners_after
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def to_dict(self):
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return {
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'owners_after': self.owners_after,
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'condition': self.condition_uri,
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'cid': self.cid
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}
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@classmethod
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def from_dict(cls, cond):
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""" Serializes a BigchainDB 'jsonized' condition back to a BigchainDB Condition class.
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"""
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return cls(cond['condition'], cond['owners_after'], cond['cid'])
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class Data(object):
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def __init__(self, payload=None, payload_id=None):
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self.payload_id = payload_id if payload_id is not None else self.to_hash()
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if payload is not None and not isinstance(payload, dict):
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raise TypeError('`payload` must be a dict instance or None')
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else:
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self.payload = payload
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@classmethod
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def from_dict(cls, payload):
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try:
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return cls(payload['payload'], payload['hash'])
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except TypeError:
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return cls()
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def to_dict(self):
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if self.payload is None:
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return None
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else:
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return {
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'payload': self.payload,
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'hash': str(self.payload_id),
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}
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def to_hash(self):
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return uuid4()
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class TransactionLink(object):
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# NOTE: In an IPLD implementation, this class is not necessary anymore, as an IPLD link can simply point to an
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# object, as well as an objects properties. So instead of having a (de)serializable class, we can have a
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# simple IPLD link of the form (not clear yet how to address indexes in arrays:
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# - https://github.com/ipld/specs/issues/20
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def __init__(self, tx_id=None, cid=None):
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self.tx_id = tx_id
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self.cid = cid
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@classmethod
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def from_dict(cls, link):
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return cls(link['tx_id'], link['cid'])
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def to_dict(self):
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if self.tx_id is None and self.cid is None:
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return None
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else:
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return {
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'tx_id': self.tx_id,
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'cid': self.cid,
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}
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class Transaction(object):
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CREATE = 'CREATE'
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TRANSFER = 'TRANSFER'
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VERSION = 1
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def __init__(self, operation, fulfillments=None, conditions=None, data=None, timestamp=None, version=None):
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# TODO: Update this comment
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"""Create a new transaction in memory
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A transaction in BigchainDB is a transfer of a digital asset between two entities represented
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by public keys.
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Currently BigchainDB supports two types of operations:
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`CREATE` - Only federation nodes are allowed to use this operation. In a create operation
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a federation node creates a digital asset in BigchainDB and assigns that asset to a public
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key. The owner of the private key can then decided to transfer this digital asset by using the
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`transaction id` of the transaction as an input in a `TRANSFER` transaction.
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`TRANSFER` - A transfer operation allows for a transfer of the digital assets between entities.
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If a transaction is initialized with the inputs being `None` a `operation` `CREATE` is
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chosen. Otherwise the transaction is of `operation` `TRANSFER`.
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Args:
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# TODO: Write a description here
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fulfillments
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conditions
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operation
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data (Optional[dict]): dictionary with information about asset.
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Raises:
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TypeError: if the optional ``data`` argument is not a ``dict``.
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# TODO: Incorporate this text somewhere better in the docs of this class
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Some use cases for this class:
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1. Create a new `CREATE` transaction:
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- This means `inputs` is empty
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2. Create a new `TRANSFER` transaction:
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- This means `inputs` is a filled list (one to multiple transactions)
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3. Written transactions must be managed somehow in the user's program: use `from_dict`
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"""
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self.timestamp = timestamp if timestamp is not None else gen_timestamp()
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self.version = version if version is not None else Transaction.VERSION
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if operation is not Transaction.CREATE and operation is not Transaction.TRANSFER:
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raise TypeError('`operation` must be either CREATE or TRANSFER')
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else:
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self.operation = operation
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if conditions is not None and not isinstance(conditions, list):
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raise TypeError('`conditions` must be a list instance or None')
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elif conditions is None:
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self.conditions = []
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else:
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self.conditions = conditions
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if fulfillments is not None and not isinstance(fulfillments, list):
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raise TypeError('`fulfillments` must be a list instance or None')
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elif fulfillments is None:
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self.fulfillments = []
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else:
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self.fulfillments = fulfillments
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# TODO: rename this to data
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if data is not None and not isinstance(data, Data):
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raise TypeError('`data` must be a Data instance or None')
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else:
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self.data = data
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# TODO: This shouldn't be in the base of the Transaction class, but rather only for the client implementation,
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# since for example the Transaction class in BigchainDB doesn't have to sign transactions.
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def sign(self, private_keys):
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""" Signs a transaction
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Acts as a proxy for `_sign_fulfillments`, for exposing a nicer API to the outside.
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"""
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self._sign_fulfillments(private_keys)
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return self
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# TODO: This shouldn't be in the base of the Transaction class, but rather only for the client implementation,
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# since for example the Transaction class in BigchainDB doesn't have to sign transactions.
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def _sign_fulfillments(self, private_keys):
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if private_keys is None:
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# TODO: Figure out the correct Python error
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raise Exception('`private_keys` cannot be None')
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if not isinstance(private_keys, list):
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private_keys = [private_keys]
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# Generate public keys from private keys and match them in a dictionary:
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# key: public_key
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# value: private_key
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gen_public_key = lambda private_key: private_key.get_verifying_key().to_ascii().decode()
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key_pairs = {gen_public_key(SigningKey(private_key)): SigningKey(private_key) for private_key in private_keys}
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# TODO: The condition for a transfer-tx will come from an input
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for fulfillment, condition in zip(self.fulfillments, self.conditions):
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# NOTE: We clone the current transaction but only add the condition and fulfillment we're currently
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# working on.
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tx_partial = Transaction(self.operation, [fulfillment], [condition], self.data, self.timestamp,
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self.version)
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self._sign_fulfillment(fulfillment, str(tx_partial), key_pairs)
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# TODO: This shouldn't be in the base of the Transaction class, but rather only for the client implementation,
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# since for example the Transaction class in BigchainDB doesn't have to sign transactions.
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def _sign_fulfillment(self, fulfillment, tx_serialized, key_pairs):
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if isinstance(fulfillment.fulfillment, Ed25519Fulfillment):
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self._fulfill_simple_signature_fulfillment(fulfillment, tx_serialized, key_pairs)
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elif isinstance(fulfillment.fulfillment, ThresholdSha256Fulfillment):
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self._fulfill_threshold_signature_fulfillment(fulfillment, tx_serialized, key_pairs)
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# TODO: This shouldn't be in the base of the Transaction class, but rather only for the client implementation,
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# since for example the Transaction class in BigchainDB doesn't have to sign transactions.
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def _fulfill_simple_signature_fulfillment(self, fulfillment, tx_serialized, key_pairs):
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# TODO: Update comment
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"""Fulfill a cryptoconditions.Ed25519Fulfillment
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Args:
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fulfillment (dict): BigchainDB fulfillment to fulfill.
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parsed_fulfillment (cryptoconditions.Ed25519Fulfillment): cryptoconditions.Ed25519Fulfillment instance.
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fulfillment_message (dict): message to sign.
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key_pairs (dict): dictionary of (public_key, private_key) pairs.
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Returns:
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object: fulfilled cryptoconditions.Ed25519Fulfillment
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"""
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owner_before = fulfillment.owners_before[0]
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try:
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# NOTE: By signing the CC fulfillment here directly, we're changing the transactions's fulfillment by
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# reference, and that's good :)
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fulfillment.fulfillment.sign(tx_serialized, key_pairs[owner_before])
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except KeyError:
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raise KeypairMismatchException('Public key {} is not a pair to any of the private keys'
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.format(owner_before))
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# TODO: This shouldn't be in the base of the Transaction class, but rather only for the client implementation,
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# since for example the Transaction class in BigchainDB doesn't have to sign transactions.
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def _fulfill_threshold_signature_fulfillment(self, fulfillment, tx_serialized, key_pairs):
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# TODO: Update comment
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"""Fulfill a cryptoconditions.ThresholdSha256Fulfillment
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Args:
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fulfillment (dict): BigchainDB fulfillment to fulfill.
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parsed_fulfillment (ThresholdSha256Fulfillment): ThresholdSha256Fulfillment instance.
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fulfillment_message (dict): message to sign.
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key_pairs (dict): dictionary of (public_key, private_key) pairs.
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Returns:
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object: fulfilled cryptoconditions.ThresholdSha256Fulfillment
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"""
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for owner_before in fulfillment.owners_before:
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try:
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# TODO: CC should throw a KeypairMismatchException, instead of our manual mapping here
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# TODO FOR CC: Naming wise this is not so smart, `get_subcondition` in fact doesn't return a condition
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# but a fulfillment:(
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# TODO FOR CC: `get_subcondition` is singular. One would not expect to get a list back.
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subfulfillment = fulfillment.fulfillment.get_subcondition_from_vk(owner_before)[0]
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except IndexError:
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raise KeypairMismatchException('Public key {} cannot be found in the fulfillment'
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.format(owner_before))
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try:
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private_key = key_pairs[owner_before]
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except KeyError:
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raise KeypairMismatchException('Public key {} is not a pair to any of the private keys'
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.format(owner_before))
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subfulfillment.sign(tx_serialized, private_key)
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def fulfillments_valid(self):
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# TODO: Update Comment
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"""Verify the signature of a transaction
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A valid transaction should have been signed `current_owner` corresponding private key.
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Args:
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signed_transaction (dict): a transaction with the `signature` included.
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Returns:
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bool: True if the signature is correct, False otherwise.
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"""
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zipped_io = list(zip(self.fulfillments, self.conditions))
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if len(zipped_io) > 1:
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# TODO: The condition for a transfer-tx will come from an input
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gen_tx = lambda ffill, cond: Transaction(self.operation, [ffill], [cond], self.data, self.timestamp,
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self.version).fulfillments_valid()
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return reduce(and_, map(gen_tx, zipped_io))
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else:
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return self._fulfillment_valid()
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def _fulfillment_valid(self):
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# NOTE: We're always taking the first fulfillment, as this method is called recursively.
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# See: `fulfillments_valid`
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fulfillment = self.fulfillments[0].fulfillment
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try:
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parsed_fulfillment = CCFulfillment.from_uri(fulfillment.serialize_uri())
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# TODO: Figure out if we need all three of those errors here
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except (TypeError, ValueError, ParsingError):
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return False
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# TODO: For transfer-transaction, we'll also have to validate against the given condition
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# NOTE: We pass a timestamp here, as in case of a timeout condition we'll have to validate against it.
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return parsed_fulfillment.validate(message=Transaction._to_str(Transaction._remove_signatures(self.to_dict())),
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now=gen_timestamp())
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def transfer(self, conditions):
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return Transaction(Transaction.TRANSFER, self._fulfillments_as_inputs(), conditions)
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def _fulfillments_as_inputs(self):
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return [Fulfillment(ffill.fulfillment,
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ffill.owners_before,
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ffill.fid,
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TransactionLink(self.to_hash(), ffill.fid))
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for ffill in self.fulfillments]
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def to_dict(self):
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try:
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data = self.data.to_dict()
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except AttributeError:
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# NOTE: data can be None and that's OK
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data = None
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tx_body = {
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'fulfillments': [fulfillment.to_dict() for fulfillment in self.fulfillments],
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'conditions': [condition.to_dict() for condition in self.conditions],
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'operation': str(self.operation),
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'timestamp': self.timestamp,
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'data': data,
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}
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tx = {
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'version': self.version,
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'transaction': tx_body,
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}
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tx_id = Transaction._to_hash(Transaction._to_str(Transaction._remove_signatures(tx)))
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tx['id'] = tx_id
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return tx
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@staticmethod
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def _remove_signatures(tx_dict):
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# NOTE: Remove reference since we need `tx_dict` only for the transaction's hash
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tx_dict = deepcopy(tx_dict)
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for fulfillment in tx_dict['transaction']['fulfillments']:
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# NOTE: Not all Cryptoconditions return a `signature` key (e.g. ThresholdSha256Fulfillment), so setting it
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# to `None` in any case could yield incorrect signatures. This is why we only set it to `None` if
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# it's set in the dict.
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if 'signature' in fulfillment['details']:
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fulfillment['details']['signature'] = None
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fulfillment['fulfillment'] = None
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try:
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for subfulfillment in fulfillment['details']['subfulfillments']:
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subfulfillment['signature'] = None
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except KeyError:
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pass
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return tx_dict
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@staticmethod
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def _to_hash(value):
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return hash_data(value)
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def to_hash(self):
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return self.to_dict()['id']
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@staticmethod
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def _to_str(value):
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return serialize(value)
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def __str__(self):
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return Transaction._to_str(self.to_dict())
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@classmethod
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def from_dict(cls, tx_body):
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tx = tx_body['transaction']
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return cls(tx['operation'], [Fulfillment.from_dict(fulfillment) for fulfillment in tx['fulfillments']],
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[Condition.from_dict(condition) for condition in tx['conditions']], Data.from_dict(tx['data']),
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tx['timestamp'], tx_body['version'])
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