dlitz / python-pbkdf2 Goto Github PK

Potentially overkill.

Now that SHA-1 has a confirmed collision in the wild (thanks, Google), for security/compliance purposes the default hash algorithm should be upgraded to SHA-256.

I think users expect crypt("hi", "mom", iterations=1) to return the hash value as the 192-bit PBKDF2 result for PBKDF2("hi", "mom", iterations=1) but it does not.
Instead, the actual salt value used in crypt("hi", "mom", iterations=1) is not "mom" but is rather the value "$p5k2$1$mom".

b64encode(PBKDF2("hi", "mom", iterations=1).read(24),"./")
'dRUSa0XKUkjbqg5NOyaNy9t4F1fXTQ6T'

crypt("hi", "mom", iterations=1)
'$p5k2$1$mom$7e7fV91gTM4ceXPmLUMU45GSLvyPc2Vt'

b64encode(PBKDF2("hi", "**$p5k2$1$**mom", iterations=1).read(24),"./")
'7e7fV91gTM4ceXPmLUMU45GSLvyPc2Vt'

patch starting at line 276 sends only the salt to PBKDF2() rather than the salt plus all the decoration that comes before it:

    if iterations is None or iterations == 400:
        iterations = 400
#        salt = "$p5k2$$" + salt
        rc = "$p5k2$$" + salt
    else:
#        salt = "$p5k2$%x$%s" % (iterations, salt)
        rc = "$p5k2$%x$%s" % (iterations, salt)
    rawhash = PBKDF2(word, salt, iterations).read(24)
#    return salt + "$" + b64encode(rawhash, "./")
    return rc + "$" + b64encode(rawhash, "./")

after patching you see the returned hash is the expected value:

crypt("hi", "mom", iterations=1)
'$p5k2$1$mom$dRUSa0XKUkjbqg5NOyaNy9t4F1fXTQ6T'

I need to use space char (" ") in the 'salt' parameter (PBKDF2.crypt()) to generate a PBKDF2 key for an specific purpose. On my machine, I've already changed this code (line #271) and the tests has finished with status OK.

The line 271 became like that (space is the last char):
allowed = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789./ "