How to obtain a screen saver password

As you all know, Windows9x is only a desktop operating system, its stability and confidentiality has been criticized by everyone. Now, I'm going to explain how Windows98 's confidentiality is based on an algorithm that extracts the Windows98 's screen saver password!

First, Screen saver (hereinafter referred to as screensavers) password encryption algorithm

Usually, the evaluation of an encryption algorithm depends on how the key is generated, the encryption algorithm is strong. Windows98 's screensaver password is limited in length to a maximum of 128 characters, and its character set is the alphabet, numbers, and some punctuation marks, the visual ASCII character set. The length of the Windows98 cipher cipher is twice times the length of the plaintext, and it is stored in a binary value named Screensave_data of the HKEY_CURRENT_USER\Control Panel\Desktop of the registry subkey.

Encryption algorithm:

First of all, the Windows98 converts the cipher text into uppercase letters, and the other characters are unchanged. Then, Windows98 each ASCII value of the plaintext to the corresponding 8bits key in order or (XOR), this will give the same length of the plaintext string, convert each of these values to 16, and convert the hexadecimal values to strings, connected sequentially. , it becomes a cipher that is twice times the length of the plaintext. The key is always fixed, with a total of 128bytes. Finally, the algorithm puts the ciphertext string in the form of a hexadecimal ASCII code value and 00h as the end sign in the registration table.

The following example illustrates this algorithm:

For example, the password for the screen saver is Visual Basic, and the converted to uppercase is Visual Basic. The corresponding hexadecimal ASCII value is: password plaintext v i u A l space B a s i c ASCII value of 4c 20 42 41 53 49 43 key to EE a 1d v-A1 1b 7a 8c F8 xor 1e A7-bayi 3b DF 0e BB The result of an XOR (a hexadecimal value) is treated as a string (numeric abcdef in uppercase): 1ea72523262581593bdf0ebb. A total of 24 characters, the character is again in hexadecimal value ASCII code values as follows: Character 1 E a 7 2 5 4 8 2 6 2 5 16 The number of 31 45 41 37 32 35 34 38 32 36 32 35 characters 8 1 5 9 b d f 3 E b b 16 number 38 31 35 39 33 42 44 46 30 45 42 42 while the registry Screensave_data value is "Screensave_data" =hex:31,45,41,37,32,35,34,38,32,36, 32,35,38,31,35,39,33,42, 44,46,30,45,42,42,00 l get key Windows98 the key to the screensaver password is 128bytes, how can I know all the keys? In fact, it is very simple, encryption algorithm already know, want to know the key is not difficult. As I did in the previous analysis of the screensaver password, set a 128bytes-long screensaver password (please remember Oh *o*). Then, take out the encrypted ciphertext, a total of 256bytes, the 256 ASCII numbers are expressed as characters, two pairs of a second to synthesize a hexadecimal value, a total of 128. You can now use a calculator, one by one, the ASCII value of the plaintext (remember to convert lowercase letters to uppercase letters) with the 128 values you just obtained, you'll get all 128 keys. Here's my 128 bytes key: Key: 48,ee,76,1d,67,69,a1,1b, 7a,8c,47,f8,54,95,97,5f, 78,d9,da,6c,59,d7,6b,35, C5,77,85,18,2A, 0e,52,ff, 00,e3,1b,71,8d,34,63,eb, 91,c3,24,0f,b7,c2,f8,e3, b6,54,4c,35,54,e7,c9,49, 28,A3,85,11,0B,2C,68,FB, Ee,7d,f6,6c,e3,9c,2d,e4, 72,c3,bb,85,1a,12,3c,32, E3,6B,4F,4D,F4,A9, 24,c8, fa,78,ad,23,a1,e4,6d,9a, 04,ce,2b,c5,b6,c5,ef,93, 5c,a8,85,2b,41,37,72,fa, 57,45,41,a1,20,4f,80,b3, D5, 23,02,64,3f,6c,f1,0f.

Second, the implementation of the program to extract the password screen saver

Knowing the secret of the screensaver password, we can use VB6 to write a program to extract the program's password. Due to the length of the relationship, the program code is not listed.

Third, screen protection program

A lot of VB books will teach you how to write screen saver, nothing but how to invoke screensavers, how to respond to the keyboard, mouse events, how to set the screen saver start parameters, how to screen the hot start of alt+ctrl+del, how to make screensavers always on top and so on. But few books introduce the response of the screensaver password. In fact, it is also very easy, as long as you in the mouse and the keyboard response to the event to add a password to confirm it. In the registry subkey HKEY_CURRENT_USER\Control Panel\Desktop also has several parameters about the screensaver, the string "screensavetimeout" = "840" is the screensaver wait time, the string " ScreenSaveActive "= 1" whether to start the screen saver flag, "1" is, "0" is no DWORD value "Screensaveusepassword" =dword:00000001 is the screen saver is password protected, 00000001 for Yes, 00000000 for No. You can verify that your screensaver is protected with a password based on the value of Screensaveusepassword.

Iv. Advice

You must be careful when using passwords, try not to use the same password. If you use the password of the bank passbook to set the password of the screensaver, how easy it is for someone to take your password! This article is just for you to introduce the encryption algorithm of screensavers, I hope we have some harvest!