def checkout(self, itemid, data):
exists = 0
j = len(self.blocks) - 1
while j > 0:
if self.blocks[j].evidenceID == int(itemid):
exists = 1
if self.blocks[j].state == STATE[
'in']: # if the block contains the evidence ID and it has a state of 'checkout'
self.blocks.append(
Block.Block(
str(hashing(self.blocks[len(self.blocks) -
1])), #prev hash
datetime.now(), #timestamp
self.blocks[j].caseID, #caseID
itemid, #evidence id
STATE['out'], #state
0, #datalength
b'', #data
))
print('Case: ', self.blocks[j + 1].caseID)
print('Checked out item: ', self.blocks[j + 1].evidenceID)
print('Status: ', self.blocks[j + 1].state)
print('Time of action: ', self.blocks[j + 1].timestamp)
return
elif self.blocks[j].state == STATE['out'] or self.blocks[
j].state == STATE['dis'] or self.blocks[
j].state == STATE['des'] or self.blocks[
j].state == STATE['rel'] or self.blocks[
j].state == STATE['init']:
sys.exit(
'Evidence must be checked in first before checkout')
j = j - 1
if exists == 0:
sys.exit("This item does not exist in the blockchain")
def verify(self, isWrong=True):
flag = True
for i in range(1, len(self.blocks)):
if i == 1 or i == 2: #
print('initial Block')
elif hashing(self.blocks[i - 1]) != self.blocks[
i].prevHash: # check that previous and current hash match
flag = False
# print(binascii.hexlify(hashing(self.blocks[i - 1])) , binascii.hexlify(self.blocks[i].prevHash))
if isWrong:
print("Transactions in blockchain: ", len(self.blocks))
print("State of blockchain: ERROR")
print("Bad block: ", i)
sys.exit("Block contents do not block checksum")
elif self.blocks[i - 1].timestamp >= self.blocks[
i].timestamp: # Check if block time were registered accordinaly
flag = False
if isWrong:
print("Transactions in blockchain: ", len(self.blocks))
print("State of blockchain: ERROR")
print("Bad block: ", i)
sys.exit('Backdating at block')
if flag and len(self.blocks) != 0:
print("Transactions in blockchain: ", len(self.blocks) - 1)
print("State of blockchain: CLEAN")
else:
sys.exit('BAD intial Block')
return flag
class Blockchain():
# Blockchain Constructor
def __init__(self):
self.blocks = [] # create empty list to hold items
# Add a new block to the chain and make sure there is no item duplicate
def add(self, case, item, data):
exist = 0
for j in range(0, len(self.blocks)):
if str(self.blocks[j].evidenceID) == item:
exist = 1
if exist == 1:
sys.exit("This item already exists in the blockchain")
else:
if len(self.blocks) == 1:
self.blocks.append(
Block.Block(
str(0),
datetime.now(),
UUID(case),
item,
STATE['in'],
0,
b'', #Me
))
else:
self.blocks.append(
Block.Block(
str(hashing(self.blocks[len(self.blocks) -
1])), #prev hash
datetime.now(), #timestamp
UUID(case), #caseID
item, #evidence id
STATE['in'], #state
0, #datalength
data, #data
))
print('Case: ', self.blocks[len(self.blocks) - 1].caseID)
print('item ID: ', self.blocks[len(self.blocks) - 1].evidenceID)
print('Status: ',
self.blocks[len(self.blocks) - 1].state.decode('utf-8'))
print('Time of action: ',
self.blocks[len(self.blocks) - 1].timestamp.isoformat())
def remove(self, itemid, status, data):
exists = 0
#retrieve the first 3 leters of the status
count = 0
stat = ''
while (count < 3):
stat = stat + status[count]
count = count + 1
reason = stat.lower()
if reason == 'dis' or reason == 'des' or reason == 'rel':
j = len(self.blocks) - 1
while j > 0:
if self.blocks[j].evidenceID == int(itemid):
exists = 1
if self.blocks[j].state == STATE[
'in']: # if the block contains the evidence ID and it has a state of 'checkin'
if data == b'':
self.blocks.append(
Block.Block(
str(
hashing(self.blocks[len(self.blocks) -
1])), #prev hash
datetime.now(), #timestamp
self.blocks[j].caseID, #caseID
itemid, #evidence id
STATE[reason], #state
0, #datalength
b'', #data
))
else:
data = data + '\x00'
self.blocks.append(
Block.Block(
str(
hashing(self.blocks[len(self.blocks) -
1])), #prev hash
datetime.now(), #timestamp
self.blocks[j].caseID, #caseID
itemid, #evidence id
STATE[reason], #state
len(data), #datalength
data.encode(), #data
))
print('Case: ', self.blocks[j + 1].caseID)
print('Removed item: ', self.blocks[j + 1].evidenceID)
print('Status: ', self.blocks[j + 1].state)
#print the owner infos if the reason is RELEASED
if status == STATE['rel']:
print('Owner info: ', self.blocks[j + 1].data) #Me
print('Time of action: ', self.blocks[j + 1].timestamp)
return
elif self.blocks[j].state == STATE['out'] or self.blocks[
j].state == STATE['dis'] or self.blocks[
j].state == STATE['des'] or self.blocks[
j].state == STATE['rel'] or self.blocks[
j].state == STATE['init']:
sys.exit(
'Evidence must be checked in first before remove')
j = j - 1
else:
sys.exit('Invalid remove reason (why) input')
if exists == 0:
sys.exit("This item does not exist in the blockchain")