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If I run following code (on Python 3.5.3, Linux) the interpreter crashes with a segfault:
def pbkdf2_bin(data, salt, iterations=1000, keylen=24, hashfunc=None):
 hashfunc = hashfunc or hashlib.sha1
 mac = hmac.new(data, None, hashfunc)
 def _pseudorandom(x, mac=mac):
 h = mac.copy()
 h.update(x)
 return h.digest()
 buf = []
 for block in range(1, -(-keylen // mac.digest_size) + 1):
 rv = u = _pseudorandom(salt + _pack_int(block))
 for i in range(iterations - 1):
 u = _pseudorandom(u)
 rv = starmap(xor, zip(rv, u))
 buf.extend(rv)
 return bytes(buf[:keylen])
pbkdf2_bin(b'1234567890', b'1234567890', 200000, 32)
I was able to track it down to the line of buf.extend(rv) which apparently is causing the segfault. Note that rv is a lazy-evaluated starmap. I also get a segfault if I evaluate it by other means (e.g. by passing it to the list constructor). However, if I evaluate it immediately by wrapping the starmap constructor with the list constructor, the code works as expected. But I wasn't able yet, to further isolate the issue. FWIW, the Python 2 version [1] of this code works just fine without forcing immediate evaluation of the starmap.
Note that the code posted, except for the bits I changed in order to make it compatible with Python 3, is under the copyright of Armin Ronacher, who published it under the BSD license.
[1]: https://github.com/mitsuhiko/python-pbkdf2