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I am writing a simple tool that allows me to quickly check MD5 hash values of downloaded ISO files. Here is my algorithm:

import sys import hashlib def main(): filename = sys.argv[1] # Takes the ISO 'file' as an argument in the command line testFile = open(filename, "r") # Opens and reads the ISO 'file' # Use hashlib here to find MD5 hash of the ISO 'file'. This is where I'm having problems hashedMd5 = hashlib.md5(testFile).hexdigest() realMd5 = input("Enter the valid MD5 hash: ") # Promt the user for the valid MD5 hash if (realMd5 == hashedMd5): # Check if valid print("GOOD!") else: print("BAD!!") main()

My problem is on the 9th line when I try to take the MD5 hash of the file. I'm getting the Type Error: object supporting the buffer API required. Could anyone shed some light on to how to make this function work?

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  • Various approaches discussed here: stackoverflow.com/questions/1131220/… Commented Jul 18, 2011 at 1:31
  • Thank you! I saw that post and read through it, but still didn't fully understand Commented Jul 18, 2011 at 1:45

2 Answers 2

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The object created by hashlib.md5 doesn't take a file object. You need to feed it data a piece at a time, and then request the hash digest.

import hashlib testFile = open(filename, "rb") hash = hashlib.md5() while True: piece = testFile.read(1024) if piece: hash.update(piece) else: # we're at end of file hex_hash = hash.hexdigest() break print hex_hash # will produce what you're looking for
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Chris, if @Jeremy Banks' answer is correct, please mark it so.
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You need to read the file:

import sys import hashlib def main(): filename = sys.argv[1] # Takes the ISO 'file' as an argument in the command line testFile = open(filename, "rb") # Opens and reads the ISO 'file' # Use hashlib here to find MD5 hash of the ISO 'file'. This is where I'm having problems m = hashlib.md5() while True: data = testFile.read(4*1024*1024) if not data: break m.update(data) hashedMd5 = m.hexdigest() realMd5 = input("Enter the valid MD5 hash: ") # Promt the user for the valid MD5 hash if (realMd5 == hashedMd5): # Check if valid print("GOOD!") else: print("BAD!!") main()

And you probably need to open the file in binary ("rb") and read the blocks of data in chunks. An ISO file is likely too large to fit in memory.

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