diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/add_python/lilliput/multiplications.py | 41 |
1 files changed, 26 insertions, 15 deletions
diff --git a/src/add_python/lilliput/multiplications.py b/src/add_python/lilliput/multiplications.py index c5abdfc..8ca8c7f 100644 --- a/src/add_python/lilliput/multiplications.py +++ b/src/add_python/lilliput/multiplications.py @@ -76,24 +76,35 @@ M3 = ( ) -def _multiplication(m): - def _multiply(x): - return list(reversed([ - reduce(xor, (mj[i](xi) for i, xi in enumerate(reversed(x)))) - for mj in m - ])) - - return _multiply +# NB: shift directions are reversed with respect to the specification +# for powers of M_R, since the specification reverses the byte order +# for those matrices. + +MR = ( + ( _0, _Id, _0, _0, _0, _0, _0, _0), + ( _0, _0, _Id, _0, _0, _0, _0, _0), + ( _0, _0, _0, _Id, _Sr(3), _0, _0, _0), + ( _0, _0, _0, _0, _Id, _0, _0, _0), + ( _0, _0, _0, _0, _0, _Id, _Sl(3), _0), + ( _0, _0, _0, _Sl(2), _0, _0, _Id, _0), + ( _0, _0, _0, _0, _0, _0, _0, _Id), + (_Id, _0, _0, _0, _0, _0, _0, _0), +) -def _multiply_MR(lane): - multiplied_lane = [lane[(byte+1) % 8] for byte in range(0, 8)] +def _multiplication(m, reverse=True): + def ordered(l): + if reverse: + return list(reversed(list(l))) + return l - multiplied_lane[2] ^= ((lane[4] >> 3) & 0xff) - multiplied_lane[4] ^= ((lane[6] << 3) & 0xff) - multiplied_lane[5] ^= ((lane[3] << 2) & 0xff) + def _multiply(x): + return ordered( + reduce(xor, (mj[i](xi) for i, xi in enumerate(ordered(x)))) + for mj in m + ) - return multiplied_lane + return _multiply def _multiply_MR2(lane): @@ -181,7 +192,7 @@ ALPHAS = ( _multiplication(M), _multiplication(M2), _multiplication(M3), - _multiply_MR, + _multiplication(MR, reverse=False), _multiply_MR2, _multiply_MR3 ) |