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Fixes #35804 by computing the DDT of non-square sboxes properly. #36020

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Merged
merged 3 commits into from
Sep 24, 2023
Merged

Fixes #35804 by computing the DDT of non-square sboxes properly. #36020

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e594552
Change nrows to ncols
PTK12 Aug 2, 2023
59c59ee
Updated docstrings and included doctests
PTK12 Aug 3, 2023
1a9f82d
Merge branch 'develop' into develop
PTK12 Sep 17, 2023
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50 changes: 49 additions & 1 deletion src/sage/crypto/sbox.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -639,6 +639,54 @@ cdef class SBox(SageObject):
[0 0 2 2 2 2 0 0]
[0 2 2 0 0 2 2 0]
[0 0 0 0 2 2 2 2]
sage: S = SBox(7,4,8,6)
sage: S.difference_distribution_table()
[4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
[0 0 0 2 0 0 0 0 0 0 0 0 0 0 2 0]
[0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 2]
[0 2 0 0 0 0 0 0 0 0 0 0 2 0 0 0]
TESTS::
Testing square SBoxes::
sage: from sage.crypto.sbox import SBox
sage: S = SBox(7,6,0,4,2,5,1,3)
sage: S.difference_distribution_table()
[8 0 0 0 0 0 0 0]
[0 2 2 0 2 0 0 2]
[0 0 2 2 0 0 2 2]
[0 2 0 2 2 0 2 0]
[0 2 0 2 0 2 0 2]
[0 0 2 2 2 2 0 0]
[0 2 2 0 0 2 2 0]
[0 0 0 0 2 2 2 2]
Testing non-square SBoxes::
sage: from sage.crypto.sbox import SBox
sage: S = SBox(8,8,8,8)
sage: S.difference_distribution_table()
[4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
[4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
[4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
[4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
sage: S = SBox(7,4,8,6)
sage: S.difference_distribution_table()
[4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
[0 0 0 2 0 0 0 0 0 0 0 0 0 0 2 0]
[0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 2]
[0 2 0 0 0 0 0 0 0 0 0 0 2 0 0 0]
sage: S = SBox(0,0,0,1,0,0,1,3)
sage: S.difference_distribution_table()
[8 0 0 0]
[4 2 2 0]
[2 4 0 2]
[2 4 0 2]
[4 2 2 0]
[6 0 0 2]
[2 4 0 2]
[2 4 0 2]
"""
cdef Py_ssize_t nrows = 1 << self.m
cdef Py_ssize_t ncols = 1 << self.n
Expand All @@ -649,7 +697,7 @@ cdef class SBox(SageObject):
for i in range(nrows):
si = self._S_list[i]
for di in range(nrows):
L[di*nrows + si ^ self._S_list[i ^ di]] += 1
L[di*ncols + si ^ self._S_list[i ^ di]] += 1

A = matrix(ZZ, nrows, ncols, L)
A.set_immutable()
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