ent.py

import sys
import math 
if __name__=='__main__':
  for x in sys.argv[1:]:
    counts=[0]*256
    entropy=0
    with open(x,'rb') as f:
      fr=f.read()
      for xx in fr:
        counts[ord(xx)]+=1
      for count in counts:
        if count==0:
          continue
        p=1.0*count/len(fr)
        entropy -=p * math.log(p, 256)
    print '[*]%s : %f'%(x,entropy)