user2835118 user2835118 - 5 months ago 15
Python Question

How can I create a random number that is cryptographically secure in python?

I'm making a project in python and I would like to create a random number that is cryptographically secure, How can I do that? I have read online that the numbers generated by the regular randomizer are not cryptographically secure, and that the function

os.urandom(n)
returns me a string, and not a number.

Answer

You can get a list of random numbers by just applying ord function over the bytes returned by os.urandom, like this

>>> import os
>>> os.urandom(10)
'm\xd4\x94\x00x7\xbe\x04\xa2R'
>>> type(os.urandom(10))
<type 'str'>
>>> map(ord, os.urandom(10))
[65, 120, 218, 135, 66, 134, 141, 140, 178, 25]

Quoting os.urandom documentation,

Return a string of n random bytes suitable for cryptographic use.

This function returns random bytes from an OS-specific randomness source. The returned data should be unpredictable enough for cryptographic applications, though its exact quality depends on the OS implementation. On a UNIX-like system this will query /dev/urandom, and on Windows it will use CryptGenRandom().

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