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cdf_analyzer.py
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cdf_analyzer.py
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#!/usr/bin/env python3
# Cumulative distribution function (CDF) plotter. Extracted from the post below,
# all credits goes to daeumerj:
# https://gist.github.com/daeumerj/d67b44c2c87d34b15ad0082ba16b17b1
#
# What to look for at the plot?
# -----------------------------
# If the CDF plot is highly straight, the file might be compressed and/or encrypted.
# If it is not, most probably it is neither compressed nor encrypted. See the
# gist above for detailed examples; or analyze /dev/urandom or a compressed file
# yourself to get an understanding.
import seaborn as sns
import os
import sys
import numpy as np
import matplotlib.pyplot as plt
plt.rcParams['figure.figsize'] = [15, 5]
sns.set()
def plot_relative_frequency_distribution(data, filename):
# unvariate
ax = sns.distplot(np.array(list(data)),
bins=256,
kde=False,
hist_kws={'alpha': 0.8},
norm_hist=True,
color='blue')
ax.set(xlabel='Byte Value (base 10)',
ylabel='Relative Frequency',
title='Relative Frequency Histogram of Byte Values')
# control x axis range
ax.set_xlim(-10, 260)
#ax.set_ylim(0, 0.10)
ax.set_title(filename)
def plot_cdf(data, filename):
ax = sns.distplot(np.array(list(data)),
bins=256,
kde=False,
hist_kws={'histtype': 'step', 'cumulative': True,
'linewidth': 1, 'alpha': 1},
kde_kws={'cumulative': True},
norm_hist=True,
color='red')
ax.set(xlabel='Byte Value (base 10)',
ylabel='Probability',
title='CDF of Byte Values')
# control x axis range
ax.set_xlim(-10, 260)
#ax.set_ylim(0, 0.10)
def create_plots(file, fsize):
if fsize > 0:
with open(file, 'rb') as f:
data = f.read(fsize)
else:
with open(file, 'rb') as f:
data = f.read()
# control layout
grid = plt.GridSpec(1, 3, wspace=0.3, hspace=0.1)
# first plot
plt.subplot(grid[0, :2])
plot_relative_frequency_distribution(data, f.name)
# second plot
plt.subplot(grid[0, 2:])
plot_cdf(data, f.name)
plt.show()
def main(argv):
fsize = 0
if len(sys.argv) == 3:
fsize = int(sys.argv[2])
create_plots(argv[1], fsize)
if __name__ == "__main__":
if len(sys.argv) < 2:
sys.exit(
'Usage: %s <FILE> [SIZE]\nExamples:\n\t%s fw.bin\n\t%s /dev/urandom 50000' %
(sys.argv[0], sys.argv[0], sys.argv[0]))
if not os.path.exists(sys.argv[1]):
sys.exit('ERROR: %s was not found!' % sys.argv[1])
main(sys.argv)