Computing the MD5 hash of an integer in python 3?

Question

I need to compute a hash of an integer using python 3. Is there a cleaner and more efficient solution than the following?

>>> import hashlib >>> N = 123 >>> hashlib.md5(str(N).encode("ascii")).hexdigest() '202cb962ac59075b964b07152d234b70'

It seems weird to have to convert to a unicode string, then decode it to a byte array.

Community · Accepted Answer · 2018-11-28 07:14:12Z

3

A cryptographic hash such as MD5 can only be applied to bytes. There are more efficient ways of encoding a number as bytes, but you still need to follow the contract.

>>> hashlib.md5(int(-123).to_bytes(8, 'big', signed=True)).hexdigest() 'fc1063e1bcb35f0d52cdceae4626c39b'

edited Nov 28, 2018 at 7:14

CommunityBot

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answered Nov 3, 2016 at 16:47

Ignacio Vazquez-Abrams

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3 Comments

MiniQuark Over a year ago

Great, thanks Ignacio. I didn't know you could call methods on ints. Do you know how to do this in python 2 by any chance?

Ignacio Vazquez-Abrams Over a year ago

For Python 2.x you need to use struct to pack it into a bytestring.

MiniQuark Over a year ago

Yikes. One more reason to prefer python 3, then. Thanks again.

MiniQuark · Accepted Answer · 2016-11-03 17:33:34Z

Ignacio's answer is perfect, but in case you need the code to work with both python 2 and python 3, and if you have NumPy installed, then this works great:

>>> import numpy as np >>> import hashlib.md5 >>> N = 123 >>> hashlib.md5(np.int64(N)).hexdigest() 'f18b8dbefe02a0efce281deb55a209cd'

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