AttributeError: 'module' object has no attribute 'a'

Question

I am trying to learn python and trying to write a simple script. There seems to be a problem with using a raw_input created variable. I am sure it's simple, but I just don't have the background yet to figure this one out. Here is what I've tried and what works:

#!/usr/bin/python

import hashlib

v = raw_input("Enter your value: ")
print "Which hash algorithm do you want to use?"
# This fails
a = raw_input("md5, sha1, sha224, sha256, sha384, sha512: ")
h = hashlib.a(v)
h.hexdigest()

# This works

v = "password"
h = hashlib.md5(v)
h.hexdigest()

replace hashlib.a with getattr(hashlib, a)

Ismail Badawi
– Ismail Badawi

2013-08-26 03:42:05 +00:00
Commented Aug 26, 2013 at 3:42 — Ismail Badawi
– Ismail Badawi, Commented Aug 26, 2013 at 3:42

gos1 · Accepted Answer · 2013-08-26 03:42:47Z

1

a is just storing a variable with a string value. hashlib.a() is just trying to call a method called a in the hashlib module (which doesnt exist). Try instead using

h = haslib.new(a)
h.update(v)
h.hexdigest()

answered Aug 26, 2013 at 3:42

gos1

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Comments

sberry · Accepted Answer · 2013-08-26 03:46:06Z

1

hashes = ("md5", "sha1", "sha224", "sha256", "sha384", "sha512")

chosen_hash = None

while not chosen_hash:
    try_hash = raw_input("%s: " % (",".join(hashes))
    if try_hash in hashes:
        chosen_hash = try_hash

hash_func = getattr(hashlib, chosen_hash)()
hash_func.update(v)

As @gos1 suggested, you might use hashlib.new(chosen_hash) instead.

The nice thing is this will guard against someone entering foo as their choice and having your program blow up.

answered Aug 26, 2013 at 3:46

sberry

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3 Comments

nneonneo Over a year ago

Use a set literal {"md5", "sha1", ...} and this will be perfect.

gos1 Over a year ago

@sberry I agree. In a real-world application, never let a user enter raw input that might be evaluated, unless you're 100% sure that such evaluation won't break up your program, or worse...

Burhan Khalid Over a year ago

Famous last words "unless you are 100% sure"

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