http://hg.viff.dk/viff/rev/f12590662f93
changeset: 1104:f12590662f93
user: Martin Geisler <[email protected]>
date: Fri Feb 20 09:58:24 2009 +0100
summary: Initialize constants in dedicated function.
This works around a false positive reported by pyflakes. It became
confused since the alog, log, and mul variables were explicitly
deleted from the global scope when they were no longer needed. We now
define there variables as local variables in the initialize function.
diffstat:
1 file changed, 131 insertions(+), 141 deletions(-)
viff/test/rijndael.py | 272 +++++++++++++++++++++++--------------------------
diffs (293 lines):
diff -r 24ba1dae612d -r f12590662f93 viff/test/rijndael.py
--- a/viff/test/rijndael.py Thu Feb 19 16:16:46 2009 +0100
+++ b/viff/test/rijndael.py Fri Feb 20 09:58:24 2009 +0100
@@ -36,109 +36,6 @@
# [keysize][block_size]
num_rounds = {16: {16: 10, 24: 12, 32: 14}, 24: {16: 12, 24: 12, 32: 14}, 32:
{16: 14, 24: 14, 32: 14}}
-A = [[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],
- [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]]
-
-# produce log and alog tables, needed for multiplying in the
-# field GF(2^m) (generator = 3)
-alog = [1]
-for i in xrange(255):
- j = (alog[-1] << 1) ^ alog[-1]
- if j & 0x100 != 0:
- j ^= 0x11B
- alog.append(j)
-
-log = [0] * 256
-for i in xrange(1, 255):
- log[alog[i]] = i
-
-# multiply two elements of GF(2^m)
-def mul(a, b):
- if a == 0 or b == 0:
- return 0
- return alog[(log[a & 0xFF] + log[b & 0xFF]) % 255]
-
-# substitution box based on F^{-1}(x)
-box = [[0] * 8 for i in xrange(256)]
-box[1][7] = 1
-for i in xrange(2, 256):
- j = alog[255 - log[i]]
- for t in xrange(8):
- box[i][t] = (j >> (7 - t)) & 0x01
-
-B = [0, 1, 1, 0, 0, 0, 1, 1]
-
-# affine transform: box[i] <- B + A*box[i]
-cox = [[0] * 8 for i in xrange(256)]
-for i in xrange(256):
- for t in xrange(8):
- cox[i][t] = B[t]
- for j in xrange(8):
- cox[i][t] ^= A[t][j] * box[i][j]
-
-# S-boxes and inverse S-boxes
-S = [0] * 256
-Si = [0] * 256
-for i in xrange(256):
- S[i] = cox[i][0] << 7
- for t in xrange(1, 8):
- S[i] ^= cox[i][t] << (7-t)
- Si[S[i] & 0xFF] = i
-
-# T-boxes
-G = [[2, 1, 1, 3],
- [3, 2, 1, 1],
- [1, 3, 2, 1],
- [1, 1, 3, 2]]
-
-AA = [[0] * 8 for i in xrange(4)]
-
-for i in xrange(4):
- for j in xrange(4):
- AA[i][j] = G[i][j]
- AA[i][i+4] = 1
-
-for i in xrange(4):
- pivot = AA[i][i]
- if pivot == 0:
- t = i + 1
- while AA[t][i] == 0 and t < 4:
- t += 1
- assert t != 4, 'G matrix must be invertible'
- for j in xrange(8):
- AA[i][j], AA[t][j] = AA[t][j], AA[i][j]
- pivot = AA[i][i]
- for j in xrange(8):
- if AA[i][j] != 0:
- AA[i][j] = alog[(255 + log[AA[i][j] & 0xFF] - log[pivot & 0xFF]) %
255]
- for t in xrange(4):
- if i != t:
- for j in xrange(i+1, 8):
- AA[t][j] ^= mul(AA[i][j], AA[t][i])
- AA[t][i] = 0
-
-iG = [[0] * 4 for i in xrange(4)]
-
-for i in xrange(4):
- for j in xrange(4):
- iG[i][j] = AA[i][j + 4]
-
-def mul4(a, bs):
- if a == 0:
- return 0
- r = 0
- for b in bs:
- r <<= 8
- if b != 0:
- r = r | mul(a, b)
- return r
-
T1 = []
T2 = []
T3 = []
@@ -152,48 +49,141 @@
U3 = []
U4 = []
-for t in xrange(256):
- s = S[t]
- T1.append(mul4(s, G[0]))
- T2.append(mul4(s, G[1]))
- T3.append(mul4(s, G[2]))
- T4.append(mul4(s, G[3]))
+S = [0] * 256
+Si = [0] * 256
- s = Si[t]
- T5.append(mul4(s, iG[0]))
- T6.append(mul4(s, iG[1]))
- T7.append(mul4(s, iG[2]))
- T8.append(mul4(s, iG[3]))
+rcon = [1]
- U1.append(mul4(t, iG[0]))
- U2.append(mul4(t, iG[1]))
- U3.append(mul4(t, iG[2]))
- U4.append(mul4(t, iG[3]))
+def initialize():
+ """Called once at module import to initialize constants defined above."""
-# round constants
-rcon = [1]
-r = 1
-for t in xrange(1, 30):
- r = mul(2, r)
- rcon.append(r)
+ A = [[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],
+ [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]]
-del A
-del AA
-del pivot
-del B
-del G
-del box
-del log
-del alog
-del i
-del j
-del r
-del s
-del t
-del mul
-del mul4
-del cox
-del iG
+ # produce log and alog tables, needed for multiplying in the
+ # field GF(2^m) (generator = 3)
+ alog = [1]
+ for i in xrange(255):
+ j = (alog[-1] << 1) ^ alog[-1]
+ if j & 0x100 != 0:
+ j ^= 0x11B
+ alog.append(j)
+
+ log = [0] * 256
+ for i in xrange(1, 255):
+ log[alog[i]] = i
+
+ # multiply two elements of GF(2^m)
+ def mul(a, b):
+ if a == 0 or b == 0:
+ return 0
+ return alog[(log[a & 0xFF] + log[b & 0xFF]) % 255]
+
+ # substitution box based on F^{-1}(x)
+ box = [[0] * 8 for i in xrange(256)]
+ box[1][7] = 1
+ for i in xrange(2, 256):
+ j = alog[255 - log[i]]
+ for t in xrange(8):
+ box[i][t] = (j >> (7 - t)) & 0x01
+
+ B = [0, 1, 1, 0, 0, 0, 1, 1]
+
+ # affine transform: box[i] <- B + A*box[i]
+ cox = [[0] * 8 for i in xrange(256)]
+ for i in xrange(256):
+ for t in xrange(8):
+ cox[i][t] = B[t]
+ for j in xrange(8):
+ cox[i][t] ^= A[t][j] * box[i][j]
+
+ # S-boxes and inverse S-boxes
+ for i in xrange(256):
+ S[i] = cox[i][0] << 7
+ for t in xrange(1, 8):
+ S[i] ^= cox[i][t] << (7-t)
+ Si[S[i] & 0xFF] = i
+
+ # T-boxes
+ G = [[2, 1, 1, 3],
+ [3, 2, 1, 1],
+ [1, 3, 2, 1],
+ [1, 1, 3, 2]]
+
+ AA = [[0] * 8 for i in xrange(4)]
+
+ for i in xrange(4):
+ for j in xrange(4):
+ AA[i][j] = G[i][j]
+ AA[i][i+4] = 1
+
+ for i in xrange(4):
+ pivot = AA[i][i]
+ if pivot == 0:
+ t = i + 1
+ while AA[t][i] == 0 and t < 4:
+ t += 1
+ assert t != 4, 'G matrix must be invertible'
+ for j in xrange(8):
+ AA[i][j], AA[t][j] = AA[t][j], AA[i][j]
+ pivot = AA[i][i]
+ for j in xrange(8):
+ if AA[i][j] != 0:
+ AA[i][j] = alog[(255 + log[AA[i][j] & 0xFF] - log[pivot &
0xFF]) % 255]
+ for t in xrange(4):
+ if i != t:
+ for j in xrange(i+1, 8):
+ AA[t][j] ^= mul(AA[i][j], AA[t][i])
+ AA[t][i] = 0
+
+ iG = [[0] * 4 for i in xrange(4)]
+
+ for i in xrange(4):
+ for j in xrange(4):
+ iG[i][j] = AA[i][j + 4]
+
+ def mul4(a, bs):
+ if a == 0:
+ return 0
+ r = 0
+ for b in bs:
+ r <<= 8
+ if b != 0:
+ r = r | mul(a, b)
+ return r
+
+ for t in xrange(256):
+ s = S[t]
+ T1.append(mul4(s, G[0]))
+ T2.append(mul4(s, G[1]))
+ T3.append(mul4(s, G[2]))
+ T4.append(mul4(s, G[3]))
+
+ s = Si[t]
+ T5.append(mul4(s, iG[0]))
+ T6.append(mul4(s, iG[1]))
+ T7.append(mul4(s, iG[2]))
+ T8.append(mul4(s, iG[3]))
+
+ U1.append(mul4(t, iG[0]))
+ U2.append(mul4(t, iG[1]))
+ U3.append(mul4(t, iG[2]))
+ U4.append(mul4(t, iG[3]))
+
+ # round constants
+ r = 1
+ for t in xrange(1, 30):
+ r = mul(2, r)
+ rcon.append(r)
+
+# initialize constants
+initialize()
class rijndael:
def __init__(self, key, block_size = 16):
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