Created
June 4, 2015 13:43
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""" | |
Original code: | |
https://github.com/django/django/blob/master/django/utils/crypto.py | |
""" | |
import hashlib | |
import random | |
import time | |
# Use the system PRNG if possible | |
try: | |
random = random.SystemRandom() | |
using_sysrandom = True | |
except NotImplementedError: | |
import warnings | |
warnings.warn('A secure pseudo-random number generator is not available ' | |
'on your system. Falling back to Mersenne Twister.') | |
using_sysrandom = False | |
extra_seed = '' | |
def get_random_string(length=12, | |
allowed_chars='abcdefghijklmnopqrstuvwxyz' | |
'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'): | |
""" | |
Returns a securely generated random string. | |
The default length of 12 with the a-z, A-Z, 0-9 character set returns | |
a 71-bit value. log_2((26+26+10)^12) =~ 71 bits | |
""" | |
if not using_sysrandom: | |
# This is ugly, and a hack, but it makes things better than | |
# the alternative of predictability. This re-seeds the PRNG | |
# using a value that is hard for an attacker to predict, every | |
# time a random string is required. This may change the | |
# properties of the chosen random sequence slightly, but this | |
# is better than absolute predictability. | |
random.seed( | |
hashlib.sha256( | |
("%s%s%s" % ( | |
random.getstate(), | |
time.time(), | |
extra_seed)).encode('utf-8') | |
).digest()) | |
return ''.join(random.choice(allowed_chars) for i in range(length)) | |
if __name__ == '__main__': | |
# Create a random SECRET_KEY to put it in the main settings. | |
chars = 'abcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*(-_=+)' | |
secret_key = get_random_string(50, chars) | |
print('Secret key: {}'.format(secret_key)) |
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