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Issue #18582: Add 'pbkdf2_hmac' to the hashlib module.

This commit is contained in:
Christian Heimes 2013-10-13 00:52:43 +02:00
parent 3892419a7a
commit e92ef13b0a
6 changed files with 280 additions and 0 deletions
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43
Doc/library/hashlib.rst
View File

@ -32,6 +32,10 @@ digests. The modern term is secure hash.
Some algorithms have known hash collision weaknesses, refer to the "See
also" section at the end.
Hash algorithms
---------------
There is one constructor method named for each type of :dfn:`hash`. All return
a hash object with the same simple interface. For example: use :func:`sha1` to
create a SHA1 hash object. You can now feed this object with :term:`bytes-like
@ -174,6 +178,43 @@ A hash object has the following methods:
compute the digests of data sharing a common initial substring.
Key Derivation Function
-----------------------
Key derivation and key stretching algorithms are designed for secure password
hashing. Naive algorithms such as ``sha1(password)`` are not resistant
against brute-force attacks. A good password hashing function must be tunable,
slow and include a salt.
.. function:: pbkdf2_hmac(name, password, salt, rounds, dklen=None)
The function provides PKCS#5 password-based key derivation function 2. It
uses HMAC as pseudorandom function.
The string *name* is the desired name of the hash digest algorithm for
HMAC, e.g. 'sha1' or 'sha256'. *password* and *salt* are interpreted as
buffers of bytes. Applications and libraries should limit *password* to
a sensible value (e.g. 1024). *salt* should be about 16 or more bytes from
a proper source, e.g. :func:`os.urandom`.
The number of *rounds* should be chosen based on the hash algorithm and
computing power. As of 2013 a value of at least 100,000 rounds of SHA-256
have been suggested.
*dklen* is the length of the derived key. If *dklen* is ``None`` then the
digest size of the hash algorithm *name* is used, e.g. 64 for SHA-512.
>>> import hashlib, binascii
>>> dk = hashlib.pbkdf2_hmac('sha256', b'password', b'salt', 100000)
>>> binascii.hexlify(dk)
b'0394a2ede332c9a13eb82e9b24631604c31df978b4e2f0fbd2c549944f9d79a5'
.. versionadded:: 3.4
.. note:: *pbkdf2_hmac* is only available with OpenSSL 1.0 and newer.
.. seealso::
Module :mod:`hmac`
@ -189,3 +230,5 @@ A hash object has the following methods:
Wikipedia article with information on which algorithms have known issues and
what that means regarding their use.
http://www.ietf.org/rfc/rfc2898.txt
PKCS #5: Password-Based Cryptography Specification Version 2.0

8
Doc/whatsnew/3.4.rst
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@ -261,6 +261,14 @@ functools
New :func:`functools.singledispatch` decorator: see the :pep:`443`.
hashlib
-------
New :func:`hashlib.pbkdf2_hmac` function.
(Contributed by Christian Heimes in :issue:`18582`)
inspect
-------

8
Lib/hashlib.py
View File

@ -147,6 +147,14 @@ except ImportError:
new = __py_new
__get_hash = __get_builtin_constructor
# PBKDF2 requires OpenSSL 1.0+ with HMAC and SHA
try:
from _hashlib import pbkdf2_hmac
except ImportError:
pass
else:
__all__ += ('pbkdf2_hmac',)
for __func_name in __always_supported:
# try them all, some may not work due to the OpenSSL
# version not supporting that algorithm.

82
Lib/test/test_hashlib.py
View File

@ -545,6 +545,88 @@ class HashLibTestCase(unittest.TestCase):
self.assertEqual(expected_hash, hasher.hexdigest())
pbkdf2_test_vectors = [
(b'password', b'salt', 1, None),
(b'password', b'salt', 2, None),
(b'password', b'salt', 4096, None),
# too slow, it takes over a minute on a fast CPU.
#(b'password', b'salt', 16777216, None),
(b'passwordPASSWORDpassword', b'saltSALTsaltSALTsaltSALTsaltSALTsalt',
4096, -1),
(b'pass\0word', b'sa\0lt', 4096, 16),
]
pbkdf2_results = {
"sha1": [
# offical test vectors from RFC 6070
(bytes.fromhex('0c60c80f961f0e71f3a9b524af6012062fe037a6'), None),
(bytes.fromhex('ea6c014dc72d6f8ccd1ed92ace1d41f0d8de8957'), None),
(bytes.fromhex('4b007901b765489abead49d926f721d065a429c1'), None),
#(bytes.fromhex('eefe3d61cd4da4e4e9945b3d6ba2158c2634e984'), None),
(bytes.fromhex('3d2eec4fe41c849b80c8d83662c0e44a8b291a964c'
'f2f07038'), 25),
(bytes.fromhex('56fa6aa75548099dcc37d7f03425e0c3'), None),],
"sha256": [
(bytes.fromhex('120fb6cffcf8b32c43e7225256c4f837'
'a86548c92ccc35480805987cb70be17b'), None),
(bytes.fromhex('ae4d0c95af6b46d32d0adff928f06dd0'
'2a303f8ef3c251dfd6e2d85a95474c43'), None),
(bytes.fromhex('c5e478d59288c841aa530db6845c4c8d'
'962893a001ce4e11a4963873aa98134a'), None),
#(bytes.fromhex('cf81c66fe8cfc04d1f31ecb65dab4089'
# 'f7f179e89b3b0bcb17ad10e3ac6eba46'), None),
(bytes.fromhex('348c89dbcbd32b2f32d814b8116e84cf2b17'
'347ebc1800181c4e2a1fb8dd53e1c635518c7dac47e9'), 40),
(bytes.fromhex('89b69d0516f829893c696226650a8687'), None),],
"sha512": [
(bytes.fromhex('867f70cf1ade02cff3752599a3a53dc4af34c7a669815ae5'
'd513554e1c8cf252c02d470a285a0501bad999bfe943c08f'
'050235d7d68b1da55e63f73b60a57fce'), None),
(bytes.fromhex('e1d9c16aa681708a45f5c7c4e215ceb66e011a2e9f004071'
'3f18aefdb866d53cf76cab2868a39b9f7840edce4fef5a82'
'be67335c77a6068e04112754f27ccf4e'), None),
(bytes.fromhex('d197b1b33db0143e018b12f3d1d1479e6cdebdcc97c5c0f8'
'7f6902e072f457b5143f30602641b3d55cd335988cb36b84'
'376060ecd532e039b742a239434af2d5'), None),
(bytes.fromhex('8c0511f4c6e597c6ac6315d8f0362e225f3c501495ba23b8'
'68c005174dc4ee71115b59f9e60cd9532fa33e0f75aefe30'
'225c583a186cd82bd4daea9724a3d3b8'), 64),
(bytes.fromhex('9d9e9c4cd21fe4be24d5b8244c759665'), None),],
}
@unittest.skipUnless(hasattr(hashlib, 'pbkdf2_hmac'),
'pbkdf2_hmac required for this test.')
def test_pbkdf2_hmac(self):
pbkdf2 = hashlib.pbkdf2_hmac
for digest_name, results in self.pbkdf2_results.items():
for i, vector in enumerate(self.pbkdf2_test_vectors):
password, salt, rounds, dklen = vector
expected, overwrite_dklen = results[i]
if overwrite_dklen:
dklen = overwrite_dklen
out = pbkdf2(digest_name, password, salt, rounds, dklen)
self.assertEqual(out, expected,
(digest_name, password, salt, rounds, dklen))
out = pbkdf2(digest_name, memoryview(password),
memoryview(salt), rounds, dklen)
out = pbkdf2(digest_name, bytearray(password),
bytearray(salt), rounds, dklen)
self.assertEqual(out, expected)
if dklen is None:
out = pbkdf2(digest_name, password, salt, rounds)
self.assertEqual(out, expected,
(digest_name, password, salt, rounds))
self.assertRaises(TypeError, pbkdf2, b'sha1', b'pass', b'salt', 1)
self.assertRaises(TypeError, pbkdf2, 'sha1', 'pass', 'salt', 1)
self.assertRaises(ValueError, pbkdf2, 'sha1', b'pass', b'salt', 0)
self.assertRaises(ValueError, pbkdf2, 'sha1', b'pass', b'salt', -1)
self.assertRaises(ValueError, pbkdf2, 'sha1', b'pass', b'salt', 1, 0)
self.assertRaises(ValueError, pbkdf2, 'sha1', b'pass', b'salt', 1, -1)
with self.assertRaisesRegex(ValueError, 'unsupported hash type'):
pbkdf2('unknown', b'pass', b'salt', 1)
if __name__ == "__main__":
unittest.main()

3
Misc/NEWS
View File

@ -42,6 +42,9 @@ Core and Builtins
Library
-------
- Issue #18582: Add 'pbkdf2_hmac' to the hashlib module. It implements PKCS#5
password-based key derivation functions with HMAC as pseudorandom function.
- Issue #19131: The aifc module now correctly reads and writes sampwidth of
compressed streams.

136
Modules/_hashopenssl.c
View File

@ -22,6 +22,7 @@
#include <openssl/evp.h>
/* We use the object interface to discover what hashes OpenSSL supports. */
#include <openssl/objects.h>
#include "openssl/err.h"
#define MUNCH_SIZE INT_MAX
@ -61,6 +62,34 @@ DEFINE_CONSTS_FOR_NEW(sha384)
DEFINE_CONSTS_FOR_NEW(sha512)
#endif
static PyObject *
_setException(PyObject *exc)
{
unsigned long errcode;
const char *lib, *func, *reason;
errcode = ERR_peek_last_error();
if (!errcode) {
PyErr_SetString(exc, "unknown reasons");
return NULL;
}
ERR_clear_error();
lib = ERR_lib_error_string(errcode);
func = ERR_func_error_string(errcode);
reason = ERR_reason_error_string(errcode);
if (lib && func) {
PyErr_Format(exc, "[%s: %s] %s", lib, func, reason);
}
else if (lib) {
PyErr_Format(exc, "[%s] %s", lib, reason);
}
else {
PyErr_SetString(exc, reason);
}
return NULL;
}
static EVPobject *
newEVPobject(PyObject *name)
@ -466,6 +495,109 @@ EVP_new(PyObject *self, PyObject *args, PyObject *kwdict)
return ret_obj;
}
#if (OPENSSL_VERSION_NUMBER >= 0x10000000 && !defined(OPENSSL_NO_HMAC) \
&& !defined(OPENSSL_NO_SHA))
#define PY_PBKDF2_HMAC 1
PyDoc_STRVAR(pbkdf2_hmac__doc__,
"pbkdf2_hmac(hash_name, password, salt, iterations, dklen=None) -> key\n\
\n\
Password based key derivation function 2 (PKCS #5 v2.0) with HMAC as\n\
pseudorandom function.");
static PyObject *
pbkdf2_hmac(PyObject *self, PyObject *args, PyObject *kwdict)
{
static char *kwlist[] = {"hash_name", "password", "salt", "iterations",
"dklen", NULL};
PyObject *key_obj = NULL, *dklen_obj = Py_None;
char *name, *key;
Py_buffer password, salt;
long iterations, dklen;
int retval;
const EVP_MD *digest;
if (!PyArg_ParseTupleAndKeywords(args, kwdict, "sy*y*l|O:pbkdf2_hmac",
kwlist, &name, &password, &salt,
&iterations, &dklen_obj)) {
return NULL;
}
digest = EVP_get_digestbyname(name);
if (digest == NULL) {
PyErr_SetString(PyExc_ValueError, "unsupported hash type");
goto end;
}
if (password.len > INT_MAX) {
PyErr_SetString(PyExc_OverflowError,
"password is too long.");
goto end;
}
if (salt.len > INT_MAX) {
PyErr_SetString(PyExc_OverflowError,
"salt is too long.");
goto end;
}
if (iterations < 1) {
PyErr_SetString(PyExc_ValueError,
"iteration value must be greater than 0.");
goto end;
}
if (iterations > INT_MAX) {
PyErr_SetString(PyExc_OverflowError,
"iteration value is too great.");
goto end;
}
if (dklen_obj == Py_None) {
dklen = EVP_MD_size(digest);
} else {
dklen = PyLong_AsLong(dklen_obj);
if ((dklen == -1) && PyErr_Occurred()) {
goto end;
}
}
if (dklen < 1) {
PyErr_SetString(PyExc_ValueError,
"key length must be greater than 0.");
goto end;
}
if (dklen > INT_MAX) {
/* INT_MAX is always smaller than dkLen max (2^32 - 1) * hLen */
PyErr_SetString(PyExc_OverflowError,
"key length is too great.");
goto end;
}
key_obj = PyBytes_FromStringAndSize(NULL, dklen);
if (key_obj == NULL) {
goto end;
}
key = PyBytes_AS_STRING(key_obj);
Py_BEGIN_ALLOW_THREADS
retval = PKCS5_PBKDF2_HMAC((char*)password.buf, password.len,
(unsigned char *)salt.buf, salt.len,
iterations, digest, dklen,
(unsigned char *)key);
Py_END_ALLOW_THREADS
if (!retval) {
Py_CLEAR(key_obj);
_setException(PyExc_ValueError);
goto end;
}
end:
PyBuffer_Release(&password);
PyBuffer_Release(&salt);
return key_obj;
}
#endif
/* State for our callback function so that it can accumulate a result. */
typedef struct _internal_name_mapper_state {
@ -588,6 +720,10 @@ GEN_CONSTRUCTOR(sha512)
static struct PyMethodDef EVP_functions[] = {
{"new", (PyCFunction)EVP_new, METH_VARARGS|METH_KEYWORDS, EVP_new__doc__},
#ifdef PY_PBKDF2_HMAC
{"pbkdf2_hmac", (PyCFunction)pbkdf2_hmac, METH_VARARGS|METH_KEYWORDS,
pbkdf2_hmac__doc__},
#endif
CONSTRUCTOR_METH_DEF(md5),
CONSTRUCTOR_METH_DEF(sha1),
#ifdef _OPENSSL_SUPPORTS_SHA2