def tth_generate(self,file): # Generates the Tiger Tree Hash (Merkle Tree) for a given file
# During the hashing of the raw data from the file, the leaf hash function uses the marker 0x00 prepended to the data before tiger hashing it. Similarly, the marker 0x01 is prepended in case of internal nodes.
blocksize = 1024 # Standard Block Size
filesize = os.path.getsize(file) # Get filesize for subsequent calculations
if filesize==0: return [[self.tiger_hash(chr(0))]] # On failure of getsize or if file is empty, return hash for empty file.
try: handle = open(file,"rb") # Open file for reading in binary mode
except: return None # If it doesnt exist or is inaccessible, dont bother.
level = [[]] # List of Levels, Level 0 Empty
for i in range(int(math.ceil(float(filesize)/blocksize))):
block = handle.read(blocksize) # Read part of the file
level[0].append(self.tiger_hash(chr(0)+block)) # Hash that part only, and put it in Level 0
handle.close() # Close file
current = 0 # Starting from level 0
while len(level[0])>1: # If whole file hasent been hashed yet
level.append([]) # Create new level
for i in range(len(level[current])/2): # For all hash pairs
level[1].append( self.tiger_hash(chr(1)+level[0][2*i]+level[0][2*i+1]) ) # Combine two hashes to get a binary tree like structure.
if len(level[0])%2==1: level[1].append(level[0][-1]) # If last item cannot be paired, promote it untouched.
del level[0] # Discard lower level hashes, as they are no longer necessary
return base64.b32encode(level[0][0])[:-1] # Result will be 40 characters; discarding the trailing '=' makes it 39
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