import json from time import sleep import cryptoconditions as cc from bigchaindb import Bigchain, util, crypto, exceptions b = Bigchain() """ Create a Digital Asset """ # create a test user testuser1_priv, testuser1_pub = crypto.generate_key_pair() # define a digital asset data payload digital_asset_payload = {'msg': 'Hello BigchainDB!'} # a create transaction uses the operation `CREATE` and has no inputs tx = b.create_transaction(b.me, testuser1_pub, None, 'CREATE', payload=digital_asset_payload) # all transactions need to be signed by the user creating the transaction tx_signed = b.sign_transaction(tx, b.me_private) # write the transaction to the bigchain # the transaction will be stored in a backlog where it will be validated, # included in a block, and written to the bigchain b.write_transaction(tx_signed) sleep(8) """ Read the Creation Transaction from the DB """ tx_retrieved = b.get_transaction(tx_signed['id']) print(json.dumps(tx_retrieved, sort_keys=True, indent=4, separators=(',', ':'))) print(testuser1_pub) print(b.me) print(tx_retrieved['id']) """ Transfer the Digital Asset """ # create a second testuser testuser2_priv, testuser2_pub = crypto.generate_key_pair() # retrieve the transaction with condition id tx_retrieved_id = b.get_owned_ids(testuser1_pub).pop() print(json.dumps(tx_retrieved_id, sort_keys=True, indent=4, separators=(',', ':'))) # create a transfer transaction tx_transfer = b.create_transaction(testuser1_pub, testuser2_pub, tx_retrieved_id, 'TRANSFER') # sign the transaction tx_transfer_signed = b.sign_transaction(tx_transfer, testuser1_priv) b.validate_transaction(tx_transfer_signed) # write the transaction b.write_transaction(tx_transfer_signed) sleep(8) # check if the transaction is already in the bigchain tx_transfer_retrieved = b.get_transaction(tx_transfer_signed['id']) print(json.dumps(tx_transfer_retrieved, sort_keys=True, indent=4, separators=(',', ':'))) """ Double Spends """ # create another transfer transaction with the same input tx_transfer2 = b.create_transaction(testuser1_pub, testuser2_pub, tx_retrieved_id, 'TRANSFER') # sign the transaction tx_transfer_signed2 = b.sign_transaction(tx_transfer2, testuser1_priv) # check if the transaction is valid try: b.validate_transaction(tx_transfer_signed2) except exceptions.DoubleSpend as e: print(e) """ Multiple Owners """ # Create a new asset and assign it to multiple owners tx_multisig = b.create_transaction(b.me, [testuser1_pub, testuser2_pub], None, 'CREATE') # Have the federation sign the transaction tx_multisig_signed = b.sign_transaction(tx_multisig, b.me_private) b.validate_transaction(tx_multisig_signed) b.write_transaction(tx_multisig_signed) # wait a few seconds for the asset to appear on the blockchain sleep(8) # retrieve the transaction tx_multisig_retrieved = b.get_transaction(tx_multisig_signed['id']) print(json.dumps(tx_multisig_retrieved, sort_keys=True, indent=4, separators=(',', ':'))) testuser3_priv, testuser3_pub = crypto.generate_key_pair() tx_multisig_retrieved_id = b.get_owned_ids(testuser2_pub).pop() tx_multisig_transfer = b.create_transaction([testuser1_pub, testuser2_pub], testuser3_pub, tx_multisig_retrieved_id, 'TRANSFER') tx_multisig_transfer_signed = b.sign_transaction(tx_multisig_transfer, [testuser1_priv, testuser2_priv]) b.validate_transaction(tx_multisig_transfer_signed) b.write_transaction(tx_multisig_transfer_signed) # wait a few seconds for the asset to appear on the blockchain sleep(8) # retrieve the transaction tx_multisig_transfer_retrieved = b.get_transaction(tx_multisig_transfer_signed['id']) assert tx_multisig_transfer_retrieved is not None print(json.dumps(tx_multisig_transfer_retrieved, sort_keys=True, indent=4, separators=(',', ':'))) """ Multiple Inputs and Outputs """ for i in range(3): tx_mimo_asset = b.create_transaction(b.me, testuser1_pub, None, 'CREATE') tx_mimo_asset_signed = b.sign_transaction(tx_mimo_asset, b.me_private) b.validate_transaction(tx_mimo_asset_signed) b.write_transaction(tx_mimo_asset_signed) sleep(8) # get inputs owned_mimo_inputs = b.get_owned_ids(testuser1_pub) print(len(owned_mimo_inputs)) # create a transaction tx_mimo = b.create_transaction(testuser1_pub, testuser2_pub, owned_mimo_inputs, 'TRANSFER') tx_mimo_signed = b.sign_transaction(tx_mimo, testuser1_priv) # write the transaction b.validate_transaction(tx_mimo_signed) b.write_transaction(tx_mimo_signed) print(json.dumps(tx_mimo_signed, sort_keys=True, indent=4, separators=(',', ':'))) """ Threshold Conditions """ # create some new testusers thresholduser1_priv, thresholduser1_pub = crypto.generate_key_pair() thresholduser2_priv, thresholduser2_pub = crypto.generate_key_pair() thresholduser3_priv, thresholduser3_pub = crypto.generate_key_pair() # retrieve the last transaction of testuser2 tx_retrieved_id = b.get_owned_ids(testuser2_pub).pop() # create a base template for a 1-input/3-output transaction threshold_tx = b.create_transaction(testuser2_pub, [thresholduser1_pub, thresholduser2_pub, thresholduser3_pub], tx_retrieved_id, 'TRANSFER') # create a 2-out-of-3 Threshold Cryptocondition threshold_condition = cc.ThresholdSha256Fulfillment(threshold=2) threshold_condition.add_subfulfillment(cc.Ed25519Fulfillment(public_key=thresholduser1_pub)) threshold_condition.add_subfulfillment(cc.Ed25519Fulfillment(public_key=thresholduser2_pub)) threshold_condition.add_subfulfillment(cc.Ed25519Fulfillment(public_key=thresholduser3_pub)) # update the condition in the newly created transaction threshold_tx['transaction']['conditions'][0]['condition'] = { 'details': json.loads(threshold_condition.serialize_json()), 'uri': threshold_condition.condition.serialize_uri() } # conditions have been updated, so hash needs updating threshold_tx['id'] = util.get_hash_data(threshold_tx) # sign the transaction threshold_tx_signed = b.sign_transaction(threshold_tx, testuser2_priv) b.validate_transaction(threshold_tx_signed) # write the transaction b.write_transaction(threshold_tx_signed) sleep(8) # check if the transaction is already in the bigchain tx_threshold_retrieved = b.get_transaction(threshold_tx_signed['id']) print(json.dumps(tx_threshold_retrieved, sort_keys=True, indent=4, separators=(',', ':'))) thresholduser4_priv, thresholduser4_pub = crypto.generate_key_pair() # retrieve the last transaction of thresholduser1_pub tx_retrieved_id = b.get_owned_ids(thresholduser1_pub).pop() # create a base template for a 2-input/1-output transaction threshold_tx_transfer = b.create_transaction([thresholduser1_pub, thresholduser2_pub, thresholduser3_pub], thresholduser4_pub, tx_retrieved_id, 'TRANSFER') # parse the threshold cryptocondition threshold_fulfillment = cc.Fulfillment.from_json(threshold_tx['transaction']['conditions'][0]['condition']['details']) subfulfillment1 = threshold_fulfillment.get_subcondition_from_vk(thresholduser1_pub)[0] subfulfillment2 = threshold_fulfillment.get_subcondition_from_vk(thresholduser2_pub)[0] subfulfillment3 = threshold_fulfillment.get_subcondition_from_vk(thresholduser3_pub)[0] # get the fulfillment message to sign threshold_tx_fulfillment_message = util.get_fulfillment_message(threshold_tx_transfer, threshold_tx_transfer['transaction']['fulfillments'][0], serialized=True) # clear the subconditions of the threshold fulfillment, they will be added again after signing threshold_fulfillment.subconditions = [] # sign and add the subconditions until threshold of 2 is reached subfulfillment1.sign(threshold_tx_fulfillment_message, crypto.SigningKey(thresholduser1_priv)) threshold_fulfillment.add_subfulfillment(subfulfillment1) subfulfillment2.sign(threshold_tx_fulfillment_message, crypto.SigningKey(thresholduser2_priv)) threshold_fulfillment.add_subfulfillment(subfulfillment2) # Add remaining (unfulfilled) fulfillment as a condition threshold_fulfillment.add_subcondition(subfulfillment3.condition) assert threshold_fulfillment.validate(threshold_tx_fulfillment_message) == True threshold_tx_transfer['transaction']['fulfillments'][0]['fulfillment'] = threshold_fulfillment.serialize_uri() assert b.validate_fulfillments(threshold_tx_transfer) == True assert b.validate_transaction(threshold_tx_transfer) == threshold_tx_transfer b.write_transaction(threshold_tx_transfer) print(json.dumps(threshold_tx_transfer, sort_keys=True, indent=4, separators=(',', ':'))) """ Hashlocked Conditions """ # Create a hash-locked asset without any new_owners hashlock_tx = b.create_transaction(b.me, None, None, 'CREATE') # Define a secret that will be hashed - fulfillments need to guess the secret secret = b'much secret! wow!' first_tx_condition = cc.PreimageSha256Fulfillment(preimage=secret) # The conditions list is empty, so we need to append a new condition hashlock_tx['transaction']['conditions'].append({ 'condition': { 'uri': first_tx_condition.condition.serialize_uri() }, 'cid': 0, 'new_owners': None }) # Conditions have been updated, so hash needs updating hashlock_tx['id'] = util.get_hash_data(hashlock_tx) # The asset needs to be signed by the current_owner hashlock_tx_signed = b.sign_transaction(hashlock_tx, b.me_private) # Some validations assert b.validate_transaction(hashlock_tx_signed) == hashlock_tx_signed assert b.is_valid_transaction(hashlock_tx_signed) == hashlock_tx_signed b.write_transaction(hashlock_tx_signed) print(json.dumps(hashlock_tx_signed, sort_keys=True, indent=4, separators=(',', ':'))) sleep(8) hashlockuser_priv, hashlockuser_pub = crypto.generate_key_pair() # create hashlock fulfillment tx hashlock_fulfill_tx = b.create_transaction(None, hashlockuser_priv, {'txid': hashlock_tx['id'], 'cid': 0}, 'TRANSFER') # try a wrong secret hashlock_fulfill_tx_fulfillment = cc.PreimageSha256Fulfillment(preimage=b'') hashlock_fulfill_tx['transaction']['fulfillments'][0]['fulfillment'] = \ hashlock_fulfill_tx_fulfillment.serialize_uri() assert b.is_valid_transaction(hashlock_fulfill_tx) == False # provide the right secret hashlock_fulfill_tx_fulfillment = cc.PreimageSha256Fulfillment(preimage=secret) hashlock_fulfill_tx['transaction']['fulfillments'][0]['fulfillment'] = \ hashlock_fulfill_tx_fulfillment.serialize_uri() assert b.validate_transaction(hashlock_fulfill_tx) == hashlock_fulfill_tx assert b.is_valid_transaction(hashlock_fulfill_tx) == hashlock_fulfill_tx b.write_transaction(hashlock_fulfill_tx) print(json.dumps(hashlock_fulfill_tx, sort_keys=True, indent=4, separators=(',', ':')))