http://hg.viff.dk/viff/rev/072920ec7f69
changeset: 1096:072920ec7f69
user: Marcel Keller <[email protected]>
date: Fri Jan 30 14:19:54 2009 +0100
summary: Optimization: Use lin_comb() instead of Matrix class in byte_sub().
diffstat:
1 file changed, 17 insertions(+), 12 deletions(-)
viff/aes.py | 29 +++++++++++++++++------------
diffs (51 lines):
diff -r e5bb773fb1fe -r 072920ec7f69 viff/aes.py
--- a/viff/aes.py Fri Jan 30 12:33:30 2009 +0100
+++ b/viff/aes.py Fri Jan 30 14:19:54 2009 +0100
@@ -88,15 +88,15 @@
self.runtime = runtime
self.use_exponentiation = use_exponentiation
- # matrix for byte_sub
- A = Matrix([[1,0,0,0,1,1,1,1],
- [1,1,0,0,0,1,1,1],
- [1,1,1,0,0,0,1,1],
- [1,1,1,1,0,0,0,1],
- [1,1,1,1,1,0,0,0],
- [0,1,1,1,1,1,0,0],
- [0,0,1,1,1,1,1,0],
- [0,0,0,1,1,1,1,1]])
+ # matrix for byte_sub, the last column is the translation vector
+ A = Matrix([[1,0,0,0,1,1,1,1, 1],
+ [1,1,0,0,0,1,1,1, 1],
+ [1,1,1,0,0,0,1,1, 0],
+ [1,1,1,1,0,0,0,1, 0],
+ [1,1,1,1,1,0,0,0, 0],
+ [0,1,1,1,1,1,0,0, 1],
+ [0,0,1,1,1,1,1,0, 1],
+ [0,0,0,1,1,1,1,1, 0]])
def byte_sub(self, state, use_lin_comb=True):
"""ByteSub operation of Rijndael.
@@ -158,14 +158,19 @@
for i in range(len(row)):
bits = bit_decompose(invert(row[i]))
- # caution: order is lsb first
- vector = AES.A * Matrix(zip(bits)) +
Matrix(zip([1,1,0,0,0,1,1,0]))
- bits = zip(*vector.rows)[0]
+ # include the translation in the matrix multiplication
+ # (see definition of AES.A)
+ bits.append(GF256(1))
if (use_lin_comb):
+ bits = [self.runtime.lin_comb(AES.A.rows[j], bits)
+ for j in range(len(bits) - 1)]
row[i] = self.runtime.lin_comb(
[2**j for j in range(len(bits))], bits)
else:
+ # caution: order is lsb first
+ vector = AES.A * Matrix(zip(bits))
+ bits = zip(*vector.rows)[0]
row[i] = reduce(lambda x,y: x + y,
[bits[j] * 2**j for j in range(len(bits))])
_______________________________________________
viff-commits mailing list
[email protected]
http://lists.viff.dk/listinfo.cgi/viff-commits-viff.dk
