Merge branch 'master' of https://forge.aztrom.fr/valentin/Hacks

rootme/challenges/cryptanalyse/code-pseudo-random-number-generator/break.py

@@ -0,0 +1,42 @@
+#!/usr/bin/python3
+
+from datetime import datetime
+
+CHARSET = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789"
+KEY_SIZE = 32
+FIRST_SEED = 1354320000
+LAST_SEED = 1356998400
+DAY_DURATION = 86400
+BZ2_HEADER = b'\x42\x5a\x68'
+
+def gen_key(seed):
+	rand = seed
+	key = [0]*KEY_SIZE
+	for i in range(KEY_SIZE):
+		rand = (rand * 214013 + 2531011) & 0xffffffff
+		rand2 = (rand >> 16) & 0x7fff
+		key[i] = CHARSET[rand2 % len(CHARSET)]
+	return key
+
+def decipher_bz2(data, key):
+	out = bytearray()
+	for i in range(len(data)):
+		if i > 3 and out[0:3] != BZ2_HEADER:
+			return None
+		out.append(data[i] ^ ord(key[i % KEY_SIZE]))
+	return out
+
+f = open("oDjbNkIoLpaMo.bz2.crypt", mode="rb")
+data = f.read()
+f.close()
+seed = FIRST_SEED
+print(datetime.fromtimestamp(seed))
+while seed <= LAST_SEED:
+	out = decipher_bz2(data, gen_key(seed))
+	if out:
+		f = open(f"out-{seed}.bz2", mode="wb")
+		f.write(out)
+		f.close()
+	seed += 1
+	if (seed - FIRST_SEED) % DAY_DURATION == 0:
+		print(datetime.fromtimestamp(seed))

rootme/challenges/cryptanalyse/code-pseudo-random-number-generator/find_bz2_file.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+for f in out-*.bz2 ; do
+	echo "Check file $f"
+	if bunzip2 -c "$f" &> /dev/null ; then
+		echo "$f is a BZ2 file !!!"
+		echo "=> out"
+		bunzip2 -c "$f" > out
+		exit
+	fi
+done