So I am done with the code below, I will run it like this "python hw3.py < code.txt"
I think I have a problem with the indentation or something. the code.txt has a mixed up text in it that is offset using a caesar cipher but it has to be decoded using letter frequencies... any help would be appreciated
def main():
from Numeric import *
from string import maketrans
def translator(text,alphabet,key):
trantab = maketrans(alphabet,key)
return text.translate(trantab)
def caesar_decode(ciphertext,s):
alpha="abcdefghijklmnopqrstuvwxyz"
return translator(ciphertext,alpha,alpha[-s:]+alpha[:-s])
class frequency_analysis:
def __init__(self, ciphertext):
self.cor=[0.64297,0.11746,0.21902,0.33483,1.00000,0.17541,
0.15864,0.47977,0.54842,0.01205,0.06078,0.31688,0.18942,
0.53133,0.59101,0.15187,0.00748,0.47134,0.49811,0.71296,
0.21713,0.07700,0.18580,0.01181,0.15541,0.00583]
self.ciphertext=ciphertext.lower()
self.freq()
self.min_error()
self.key=self.minimum[0]
self.solution=caesar_decode(self.ciphertext,self.minimum[0])
def freq(self):
self.arr=zeros(26,Float64)
for l in self.ciphertext:
x=ord(l)
if (x>=97 and x<=122):
self.arr[x-97]+=1.0
self.arr/=max(self.arr)
def error(self):
e=0
for i in range(0,len(self.arr)):
e += abs(self.arr[i]-self.cor[i])**2
return e
def min_error(self):
self.minimum=[0,10000]
for rot in range(0,25):
e=self.error()
print rot,e
if e<self.minimum[1]:
self.minimum[1]=e
self.minimum[0]=rot
x=self.arr[-1]
del self.cor[-1]
self.cor.insert(0,x)
ciphertext="ymjwj fwj ybt ydujx tk jshwduynts: tsj ymfy bnqq "+\
"uwjajsy dtzw xnxyjw kwtr wjfinsl dtzw infwd fsi tsj ymfy bnqq "+\
"uwjajsy dtzw ltajwsrjsy. ymnx nx f ajwd nrutwyfsy qjxxts yt "+\
"wjrjgjwjxujhnfqqd ktw fyyfhpx zxnsl kwjvzjshd fsfqdxnx bmnhm "+\
"wjvznwj qtsljw ufxxflj tk yjcy ns twijw yt fhmnjaj gjyyjw wjxzqyx."
FA=frequency_analysis(ciphertext)
print FA.solution
main()
