Python scrypt bindings
Scrypt is useful when encrypting password as it is possible to specify a minimum amount of time to use when encrypting and decrypting. If, for example, a password takes 0.05 seconds to verify, a user won't notice the slight delay when signing in, but doing a brute force search of several billion passwords will take a considerable amount of time. This is in contrast to more traditional hash functions such as MD5 or the SHA family which can be implemented extremely fast on cheap hardware.
$ hg clone http://bitbucket.org/mhallin/py-scrypt $ cd py-scrypt $ python setup.py build Become superuser (or use virtualenv): # python setup.py install Run tests after install: $ python setup.py test
If you want py-scrypt for your Python 3 environment, just run the above commands with your Python 3 interpreter. Py-scrypt supports both Python 2 and 3.
The bindings are very simple -- there is an encrypt and a decrypt method on the scrypt module:
>>> import scrypt >>> data = scrypt.encrypt('a secret message', 'password', maxtime=0.1) # This will take at least 0.1 seconds >>> data[:20] 'scrypt\x00\r\x00\x00\x00\x08\x00\x00\x00\x01RX9H' >>> scrypt.decrypt(data, 'password', maxtime=0.1) # This will also take at least 0.1 seconds 'a secret message' >>> scrypt.decrypt(data, 'password', maxtime=0.05) # scrypt won't be able to decrypt this data fast enough Traceback (most recent call last): File "<stdin>", line 1, in <module> scrypt.error: decrypting file would take too long >>> scrypt.decrypt(data, 'wrong password', maxtime=0.1) # scrypt will throw an exception if the password is incorrect Traceback (most recent call last): File "<stdin>", line 1, in <module> scrypt.error: password is incorrect
From these, one can make a simple password verifier using the following functions:
def randstr(length): return ''.join(chr(random.randint(0,255)) for i in range(length)) def hash_password(password, maxtime=0.5, datalength=64): return scrypt.encrypt(randstr(datalength), password, maxtime=maxtime) def verify_password(hashed_password, guessed_password, maxtime=0.5): try: scrypt.decrypt(hashed_password, guessed_password, maxtime) return True except scrypt.error: return False
Scrypt was created by Colin Percival and is licensed as 2-clause BSD. Since scrypt does not normally build as a shared library, I have included the source for the currently latest version of the library in this repository. When a new version arrives, I will update these sources.
Burstaholic on Bitbucket provided the necessary changes to make the library build on Windows.
[Kelvin Wong] on Bitbucket provided changes to make the library available on Mac OS X 10.6 and earlier, as well as changes to make the library work more like the command-line version of scrypt by default.
This library is licensed under the same license as scrypt; 2-clause BSD.