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#!/usr/bin/python
#
# Script to generate distorted text images for a captcha system.
#
# Copyright (C) 2005 Neil Harris
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
# http://www.gnu.org/copyleft/gpl.html
#
# Further tweaks by Brion Vibber <brion@pobox.com>:
# 2006-01-26: Add command-line options for the various parameters
# 2007-02-19: Add --dirs param for hash subdirectory splits
# Tweaks by Greg Sabino Mullane <greg@turnstep.com>:
# 2008-01-06: Add regex check to skip words containing other than a-z
import random
import math
import hashlib
from optparse import OptionParser
import os
import sys
import re
import multiprocessing
import time
try:
from PIL import Image
from PIL import ImageFont
from PIL import ImageDraw
from PIL import ImageEnhance
from PIL import ImageOps
from PIL import ImageMath
except:
sys.exit("This script requires the Python Imaging Library - http://www.pythonware.com/products/pil/")
nonalpha = re.compile('[^a-z]') # regex to test for suitability of words
# Does X-axis wobbly copy, sandwiched between two rotates
def wobbly_copy(src, wob, col, scale, ang):
x, y = src.size
f = random.uniform(4*scale, 5*scale)
p = random.uniform(0, math.pi*2)
rr = ang+random.uniform(-10, 10) # vary, but not too much
int_d = Image.new('RGB', src.size, 0) # a black rectangle
rot = src.rotate(rr, Image.BILINEAR)
# Do a cheap bounding-box op here to try to limit work below
bbx = rot.getbbox()
if bbx == None:
return src
else:
l, t, r, b= bbx
# and only do lines with content on
for i in range(t, b+1):
# Drop a scan line in
xoff = int(math.sin(p+(i*f/y))*wob)
xoff += int(random.uniform(-wob*0.5, wob*0.5))
int_d.paste(rot.crop((0, i, x, i+1)), (xoff, i))
# try to stop blurring from building up
int_d = int_d.rotate(-rr, Image.BILINEAR)
enh = ImageEnhance.Sharpness(int_d)
return enh.enhance(2)
def gen_captcha(text, fontname, fontsize, file_name):
"""Generate a captcha image"""
# white text on a black background
bgcolor = 0x0
fgcolor = 0xffffff
# create a font object
font = ImageFont.truetype(fontname,fontsize)
# determine dimensions of the text
dim = font.getsize(text)
# create a new image significantly larger that the text
edge = max(dim[0], dim[1]) + 2*min(dim[0], dim[1])
im = Image.new('RGB', (edge, edge), bgcolor)
d = ImageDraw.Draw(im)
x, y = im.size
# add the text to the image
d.text((x/2-dim[0]/2, y/2-dim[1]/2), text, font=font, fill=fgcolor)
k = 2
wob = 0.09*dim[1]
rot = 45
# Apply lots of small stirring operations, rather than a few large ones
# in order to get some uniformity of treatment, whilst
# maintaining randomness
for i in range(k):
im = wobbly_copy(im, wob, bgcolor, i*2+3, rot+0)
im = wobbly_copy(im, wob, bgcolor, i*2+1, rot+45)
im = wobbly_copy(im, wob, bgcolor, i*2+2, rot+90)
rot += 30
# now get the bounding box of the nonzero parts of the image
bbox = im.getbbox()
bord = min(dim[0], dim[1])/4 # a bit of a border
im = im.crop((bbox[0]-bord, bbox[1]-bord, bbox[2]+bord, bbox[3]+bord))
# Create noise
nblock = 4
nsize = (im.size[0] / nblock, im.size[1] / nblock)
noise = Image.new('L', nsize, bgcolor)
data = noise.load()
for x in range(nsize[0]):
for y in range(nsize[1]):
r = random.randint(0, 65)
gradient = 70 * x / nsize[0]
data[x, y] = r + gradient
# Turn speckles into blobs
noise = noise.resize(im.size, Image.BILINEAR)
# Add to the image
im = ImageMath.eval('convert(convert(a, "L") / 3 + b, "RGB")', a=im, b=noise)
# and turn into black on white
im = ImageOps.invert(im)
# save the image, in format determined from filename
im.save(file_name)
def gen_subdir(basedir, md5hash, levels):
"""Generate a subdirectory path out of the first _levels_
characters of _hash_, and ensure the directories exist
under _basedir_."""
subdir = None
for i in range(0, levels):
char = md5hash[i]
if subdir:
subdir = os.path.join(subdir, char)
else:
subdir = char
fulldir = os.path.join(basedir, subdir)
if not os.path.exists(fulldir):
os.mkdir(fulldir)
return subdir
def try_pick_word(words, blacklist, verbose, nwords, min_length, max_length):
if words is not None:
word = words[random.randint(0,len(words)-1)]
while nwords > 1:
word2 = words[random.randint(0,len(words)-1)]
word = word + word2
nwords = nwords - 1
else:
word = ''
max_length = max_length if max_length > 0 else 10
for i in range(0, random.randint(min_length, max_length)):
word = word + chr(97 + random.randint(0,25))
if verbose:
print("word is %s" % word)
if len(word) < min_length:
if verbose:
print("skipping word pair '%s' because it has fewer than %d characters" % (word, min_length))
return None
if max_length > 0 and len(word) > max_length:
if verbose:
print("skipping word pair '%s' because it has more than %d characters" % (word, max_length))
return None
if nonalpha.search(word):
if verbose:
print("skipping word pair '%s' because it contains non-alphabetic characters" % word)
return None
for naughty in blacklist:
if naughty in word:
if verbose:
print("skipping word pair '%s' because it contains blacklisted word '%s'" % (word, naughty))
return None
return word
def pick_word(words, blacklist, verbose, nwords, min_length, max_length):
for x in range(1000): # If we can't find a valid combination in 1000 tries, just give up
word = try_pick_word(words, blacklist, verbose, nwords, min_length, max_length)
if word:
return word
sys.exit("Unable to find valid word combinations")
def read_wordlist(filename):
f = open(filename)
words = [x.strip().lower() for x in f.readlines()]
f.close()
return words
def run_in_thread(object):
count = object[0];
words = object[1]
blacklist = object[2]
opts = object[3]
font = object[4]
fontsize = object[5]
for i in range(count):
word = pick_word(words, blacklist, verbose, opts.number_words, opts.min_length, opts.max_length)
salt = "%08x" % random.randrange(2**32)
# 64 bits of hash is plenty for this purpose
md5hash = hashlib.md5((key+salt+word+key+salt).encode('utf-8')).hexdigest()[:16]
filename = "image_%s_%s.png" % (salt, md5hash)
if dirs:
subdir = gen_subdir(output, md5hash, dirs)
filename = os.path.join(subdir, filename)
if verbose:
print(filename)
gen_captcha(word, font, fontsize, os.path.join(output, filename))
if __name__ == '__main__':
"""This grabs random words from the dictionary 'words' (one
word per line) and generates a captcha image for each one,
with a keyed salted hash of the correct answer in the filename.
To check a reply, hash it in the same way with the same salt and
secret key, then compare with the hash value given.
"""
script_dir = os.path.dirname(os.path.realpath(__file__))
parser = OptionParser()
parser.add_option("--wordlist", help="A list of words (required)", metavar="WORDS.txt")
parser.add_option("--random", help="Use random charcters instead of a wordlist", action="store_true")
parser.add_option("--key", help="The passphrase set as $wgCaptchaSecret (required)", metavar="KEY")
parser.add_option("--output", help="The directory to put the images in - $wgCaptchaDirectory (required)", metavar="DIR")
parser.add_option("--font", help="The font to use (required)", metavar="FONT.ttf")
parser.add_option("--font-size", help="The font size (default 40)", metavar="N", type='int', default=40)
parser.add_option("--count", help="The maximum number of images to make (default 20)", metavar="N", type='int', default=20)
parser.add_option("--blacklist", help="A blacklist of words that should not be used", metavar="FILE", default=os.path.join(script_dir, "blacklist"))
parser.add_option("--fill", help="Fill the output directory to contain N files, overrides count, cannot be used with --dirs", metavar="N", type='int')
parser.add_option("--dirs", help="Put the images into subdirectories N levels deep - $wgCaptchaDirectoryLevels", metavar="N", type='int')
parser.add_option("--verbose", "-v", help="Show debugging information", action='store_true')
parser.add_option("--number-words", help="Number of words from the wordlist which make a captcha challenge (default 2)", type='int', default=2)
parser.add_option("--min-length", help="Minimum length for a captcha challenge", type='int', default=1)
parser.add_option("--max-length", help="Maximum length for a captcha challenge", type='int', default=-1)
parser.add_option("--threads", help="Maximum number of threads to be used to generate captchas.", type='int', default=1)
opts, args = parser.parse_args()
if opts.wordlist:
wordlist = opts.wordlist
elif opts.random:
wordlist = None
else:
sys.exit("Need to specify a wordlist")
if opts.key:
key = opts.key
else:
sys.exit("Need to specify a key")
if opts.output:
output = opts.output
else:
sys.exit("Need to specify an output directory")
if opts.font and os.path.exists(opts.font):
font = opts.font
else:
sys.exit("Need to specify the location of a font")
blacklist = read_wordlist(opts.blacklist)
count = opts.count
fill = opts.fill
dirs = opts.dirs
verbose = opts.verbose
fontsize = opts.font_size
threads = opts.threads
if fill:
count = max(0, fill - len(os.listdir(output)))
words = None
if wordlist:
words = read_wordlist(wordlist)
words = [x for x in words
if len(x) in (4,5) and x[0] != "f"
and x[0] != x[1] and x[-1] != x[-2]]
if count == 0:
sys.exit("No need to generate CAPTCHA images.")
if count < threads:
chunks = 1
threads = 1
else:
chunks = (count / threads)
p = multiprocessing.Pool(threads);
data = []
print("Generating %s CAPTCHA images separated in %s image(s) per chunk run by %s threads..." % (count, chunks, threads))
for i in range(0, threads):
data.append([chunks, words, blacklist, opts, font, fontsize])
p.map(run_in_thread, data)