This article only discusses the rar password cracking. If you have any ideas, please put forward.
The title is a bit exaggerated. The fact is that I can't come up with a better description summary The content of this article is why I wrote such a title.
Background: A BBS entertainment area publishes one of the 49 lottery tickets. The rules are very simple. Each time the administrator sets a number of 1 to 49, places it in a txt file, and then uses rar encryption to upload it to the post enclosure Then, members can buy the number they choose with forum currency, corresponding to how many bets they can choose, how much each bet costs, and so on.
problem reflection : From the perspective of rar, network There are still a lot of software for brute force cracking, but if your password strength is good enough, for example, the number of letters and special symbols together can reach dozens, and the PC can't be cracked without shutting down for a few days. Therefore, this method is the most undesirable. When the cost of cracking code is far greater than the value of the target, no one will do so.
RAR has a small problem: it is not necessarily a small problem, but only for such small text files. See the figure:
Readers can test for themselves. A byte of txt text (that is, a txt text contains only one number) has a size of 1 before compression, 1 after compression, and 16 after encryption and compression; The two byte txt text is 2 before compression, 2 after compression, and 16 after encryption. If the text is encoded in utf-8, the corresponding text will be 3 times larger than the ansi code, and it will still be 16 after encryption and compression.
Contradiction: The compressed document of rar provides a CRC32 This value is the CRC32 value of the document before compression. It is believed that many people know that every different file has a unique CRC32 value. Even if there may be duplicates, the txt text in the small range of contents from 1 to 49 will not have duplicates. To this end, I use the hash detection tool to test one by one and list a table.
Value of content CRC32 in txt text
1 83DCEFB7
01 CF412436
2 1AD5BE0D
02 5648758C
3 6DD28E9B
03 214F451A
4 F3B61B38
04 BF2BD0B9
5 84B12BAE
05 C82CE02F
6 1DB87A14
06 5125B195
7 6ABF4A82
07 26228103
8 FA005713
08 B69D9C92
9 8D076785
09 C19AAC04
10 A15D25E1
11 D65A1577
12 4F5344CD
13 3854745B
14 A630E1F8
15 D137D16E
16 483E80D4
17 3F39B042
18 AF86ADD3
19 D8819D45
20 8A707622
21 FD7746B4
22 647E170E
23 13792798
24 8D1DB23B
25 FA1A82AD
26 6313D317
27 1414E381
28 84ABFE10
29 F3ACCE86
30 936B4763
31 E46C77F5
32 7D65264F
33 &nbs
p; 0A6216D9
34 9406837A
35 E301B3EC
36 7A08E256
37 0D0FD2C0
38 9DB0CF51
39 EAB7FFC7
40 DC2AD1A4
41 AB2DE132
42 3224B088
43 4523801E
44 DB4715BD
45 AC40252B
46 35497491
47 424E4407
48 D2F15996
49 A5F66900
Obviously, there is no repetition. (The above is tested during ansi coding. UTF-8 is definitely different from this.)
Problem solving: According to the table listed above, picture The content of the txt text document in which CRC32 is 13792798 is 23.
The anti cracking method is to add any other text in the text. ha-ha...
Please specify: Bird Blog » Teach you to bypass rar password
