attack.py

@@ -0,0 +1,82 @@
+# dead simple dictionary attack for fixed-length passwords.
+# this is far from optimal.
+
+from collections import defaultdict
+import argparse
+import sys
+import random
+
+program = sys.argv[0]
+args = sys.argv[1:]
+
+parser = argparse.ArgumentParser(
+    description="attack: produce fixed-length strings from dictionaries")
+
+parser.add_argument(
+    'length', type=int,
+    help="the length of the strings to output")
+parser.add_argument(
+    'path', metavar='text-file', nargs='+',
+    help="a dictionary file containing one string per line")
+parser.add_argument(
+    '-n', metavar='limit', type=float, default='inf',
+    help="output this many strings and exit")
+parser.add_argument(
+    '-s', metavar='seed', type=int, default=None,
+    help="use as a seed for the random number generator")
+
+a = parser.parse_args(args)
+seed = a.s
+limit = a.n
+paths = a.path
+fixed_length = a.length
+del a
+
+lines = []
+for path in paths:
+    with open(path, "r") as f:
+        for line in f:
+            lines.append(line.strip('\r\n'))
+
+nlines = defaultdict(lambda: [])
+ncount = defaultdict(lambda: 0)
+for line in lines:
+    length = len(line)
+    if length == 0 or length > fixed_length:
+        continue
+    nlines[length].append(line)
+    ncount[length] += 1
+
+del lines
+
+if seed is not None:
+    random.seed(seed)
+
+lengths = list(ncount.keys())
+length_weights = list(ncount.values())
+
+i = 0
+while i < limit:
+    s = ''
+    new_weights = length_weights.copy()
+
+    while len(s) < fixed_length:
+        if len(s) > 0:
+            for j, length in enumerate(lengths):
+                if len(s) + length > fixed_length:
+                    new_weights[j] = 0
+
+        if sum(new_weights) == 0:
+            s = ''
+            new_weights = length_weights.copy()
+            continue
+
+        chosen_length = random.choices(lengths, new_weights)[0]
+        s += random.choice(nlines[chosen_length])
+
+    try:
+        print(s)
+    except OSError:
+        # pipe closed.
+        break
+    i += 1