8000 bpo-31933: fix blake2 multi-byte params on big endian platforms (#4250) · python/cpython@dcfb0e3 · GitHub
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bpo-31933: fix blake2 multi-byte params on big endian platforms (#4250)
All Blake2 params have to be encoded in little-endian byte order. For the two multi-byte integer params, leaf_length and node_offset, that means that assigning a native-endian integer to them appears to work on little-endian platforms, but gives the wrong result on big-endian. The current libb2 API doesn't make that very clear, and @sneves is working on new API functions in the GH issue above. In the meantime, we can work around the problem by explicitly assigning little-endian values to the parameter block. See BLAKE2/libb2#12.
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‎Lib/test/test_hashlib.py

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@@ -615,6 +615,24 @@ def test_case_blake2b_1(self):
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"ba80a53f981c4d0d6a2797b69f12f6e94c212f14685ac4b74b12bb6fdbffa2d1"+
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"7d87c5392aab792dc252d5de4533cc9518d38aa8dbf1925ab92386edd4009923")
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@requires_blake2
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def test_case_blake2b_all_parameters(self):
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# This checks that all the parameters work in general, and also that
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# parameter byte order doesn't get confused on big endian platforms.
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self.check('blake2b', b"foo",
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"920568b0c5873b2f0ab67bedb6cf1b2b",
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digest_size=16,
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key=b"bar",
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salt=b"baz",
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person=b"bing",
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fanout=2,
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depth=3,
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leaf_size=4,
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node_offset=5,
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node_depth=6,
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inner_size=7,
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last_node=True)
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@requires_blake2
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def test_blake2b_vectors(self):
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for msg, key, md in read_vectors('blake2b'):
@@ -640,6 +658,24 @@ def test_case_blake2s_1(self):
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self.check('blake2s', b"abc",
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"508c5e8c327c14e2e1a72ba34eeb452f37458b209ed63a294d999b4c86675982")
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@requires_blake2
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def test_case_blake2s_all_parameters(self):
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# This checks that all the parameters work in general, and also that
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# parameter byte order doesn't get confused on big endian platforms.
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self.check('blake2s', b"foo",
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"bf2a8f7fe3c555012a6f8046e646bc75",
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digest_size=16,
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key=b"bar",
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salt=b"baz",
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person=b"bing",
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fanout=2,
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depth=3,
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leaf_size=4,
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node_offset=5,
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node_depth=6,
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inner_size=7,
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last_node=True)
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@requires_blake2
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def test_blake2s_vectors(self):
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for msg, key, md in read_vectors('blake2s'):

‎Misc/NEWS.d/next/Library/2017-11-03-08-36-03.bpo-31933.UrtoMP.rst

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@@ -0,0 +1,2 @@
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Fix Blake2 params leaf_size and node_offset on big endian platforms. Patch
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by Jack O'Connor.

‎Modules/_blake2/blake2b_impl.c

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -162,7 +162,8 @@ py_blake2b_new_impl(PyTypeObject *type, PyObject *data, int digest_size,
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goto error;
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}
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}
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self->param.leaf_length = (unsigned int)leaf_size;
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// NB: Simple assignment here would be incorrect on big endian platforms.
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store32(&(self->param.leaf_length), leaf_size);
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if (node_offset_obj != NULL) {
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node_offset = PyLong_AsUnsignedLongLong(node_offset_obj);
@@ -178,7 +179,8 @@ py_blake2b_new_impl(PyTypeObject *type, PyObject *data, int digest_size,
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}
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store48(&(self->param.node_offset), node_offset);
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#else
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self->param.node_offset = node_offset;
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// NB: Simple assignment here would be incorrect on big endian platforms.
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store64(&(self->param.node_offset), node_offset);
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#endif
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if (node_depth < 0 || node_depth > 255) {

‎Modules/_blake2/blake2s_impl.c

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -162,7 +162,8 @@ py_blake2s_new_impl(PyTypeObject *type, PyObject *data, int digest_size,
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goto error;
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}
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}
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self->param.leaf_length = (unsigned int)leaf_size;
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// NB: Simple assignment here would be incorrect on big endian platforms.
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store32(&(self->param.leaf_length), leaf_size);
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if (node_offset_obj != NULL) {
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node_offset = PyLong_AsUnsignedLongLong(node_offset_obj);
@@ -178,7 +179,8 @@ py_blake2s_new_impl(PyTypeObject *type, PyObject *data, int digest_size,
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}
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store48(&(self->param.node_offset), node_offset);
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#else
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self->param.node_offset = node_offset;
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// NB: Simple assignment here would be incorrect on big endian platforms.
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store64(&(self->param.node_offset), node_offset);
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#endif
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if (node_depth < 0 || node_depth > 255) {

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