def createHashTablesecond(self):
"""
eliminate as many keys as possible, brute force the remaining ones by calling tryencryption()
"""
print "Testing..."
nbTried = 0
self.temp = CMEA()
print "K4"
for k4 in xrange(128):
print k4
for k5 in xrange(256):
for (k6,k7) in self.possible67:
tpp = [self.calcpp(a,ta,k4,k5,k6,k7) for (a,ta) in self.tuples]
if [] in tpp:
continue
for (a,b,c,d) in [(a,b,c,d) for a in tpp[0] for b in tpp[1] for c in tpp[2] for d in tpp[3]]:
m = ((a-d)%256,(b-d)%256, (c-d)%256)
m = m[0]*256**2 + m[1]*256+m[2]
if m in self.startmap:
for k in self.startmap[m]:
nbTried = nbTried + 1
key = k[:3]
key.append((a-k[3])%256)
key.extend([k4,k5,k6,k7])
if self.trialencryption(key):
print "key found: ",key
print "this key may not be the exact same one, but it is equivalent..."
print "keys tried: ", nbTried
return True
def __init__(self):
nbplaintext = 80
self.p0 = [ [ True for i in range(256) ] for j in range(256) ]
for i in range(256):
for j in range(256):
if(not ((j-i) % 256) in cavetable):
self.p0[i][j] = False
self.CVI = CVInverse()
self.p = None
self.c = CMEA()
self.texts = self.createPlaintexts(nbplaintext, self.c)
# if one of the value if knwon (because the cave table invalidate one of the option) we can deduce the other value
posj = [tj, tj + 1]
posz = [(tj - c) % 256, (tj + 1 - c) % 256]
posj = [k for k in posj if (k - j) % 256 in cavetable]
posz = [k for k in posz if (k - z) % 256 in cavetable]
if len(posj) == 1:
self.known[j] = posj[0]
if len(posz) == 1:
self.known[z] = posz[0]
return compteur
if __name__ == '__main__':
d = Decrypter()
d.setCrypter(CMEA())
d.c.blocksize = 3
d.c.createRandomKey()
possibilities = d.findTzero()
print "number of possible values for t0:", len(possibilities)
for p in possibilities:
# checks if the value for t0 is correct
t = d.findPossibleOthers(p)
if t != []:
break
d.getallconstraints(t[0][0])
for i in range(10):
print "number of Tbox output known at iteration ", i, " :", len(
d.known)
