Asked By – user2344996
I have written some code in Python that checks for an MD5 hash in a file and makes sure the hash matches that of the original.
Here is what I have developed:
# Defines filename filename = "file.exe" # Gets MD5 from file def getmd5(filename): return m.hexdigest() md5 = dict() for fname in filename: md5[fname] = getmd5(fname) # If statement for alerting the user whether the checksum passed or failed if md5 == '>md5 will go here<': print("MD5 Checksum passed. You may now close this window") input ("press enter") else: print("MD5 Checksum failed. Incorrect MD5 in file 'filename'. Please download a new copy") input("press enter") exit
But whenever I run the code, I get the following error:
Traceback (most recent call last): File "C:\Users\Username\md5check.py", line 13, in <module> md5[fname] = getmd5(fname) File "C:\Users\Username\md5check.py, line 9, in getmd5 return m.hexdigest() NameError: global name 'm' is not defined
Is there anything I am missing in my code?
Now we will see solution for issue: How do I calculate the MD5 checksum of a file in Python? [duplicate]
In regards to your error and what’s missing in your code.
m is a name which is not defined for
No offence, I know you are a beginner, but your code is all over the place. Let’s look at your issues one by one 🙂
First, you are not using
hashlib.md5.hexdigest() method correctly. Please refer explanation on hashlib functions in Python Doc Library. The correct way to return MD5 for provided string is to do something like this:
>>> import hashlib >>> hashlib.md5("example string").hexdigest() '2a53375ff139d9837e93a38a279d63e5'
However, you have a bigger problem here. You are calculating MD5 on a file name string, where in reality MD5 is calculated based on file contents. You will need to basically read file contents and pipe it though MD5. My next example is not very efficient, but something like this:
>>> import hashlib >>> hashlib.md5(open('filename.exe','rb').read()).hexdigest() 'd41d8cd98f00b204e9800998ecf8427e'
As you can clearly see second MD5 hash is totally different from the first one. The reason for that is that we are pushing contents of the file through, not just file name.
A simple solution could be something like that:
# Import hashlib library (md5 method is part of it) import hashlib # File to check file_name = 'filename.exe' # Correct original md5 goes here original_md5 = '5d41402abc4b2a76b9719d911017c592' # Open,close, read file and calculate MD5 on its contents with open(file_name, 'rb') as file_to_check: # read contents of the file data = file_to_check.read() # pipe contents of the file through md5_returned = hashlib.md5(data).hexdigest() # Finally compare original MD5 with freshly calculated if original_md5 == md5_returned: print "MD5 verified." else: print "MD5 verification failed!."
Please look at the post Python: Generating a MD5 checksum of a file. It explains in detail a couple of ways how it can be achieved efficiently.
Best of luck.
This question is answered By – PSS
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