Doom cheat code encryption - Revision history

Foxtrot at 11:46, 13 January 2023

2023-01-13T11:46:32Z

Dan Tobias: /* Details */

2019-11-03T00:56:58Z

‎Details

Dan Tobias at 00:56, 3 November 2019

2019-11-03T00:56:30Z

Dan Tobias at 00:56, 3 November 2019

2019-11-03T00:56:11Z

Dan Tobias at 23:07, 2 November 2019

2019-11-02T23:07:17Z

Dan Tobias at 18:04, 2 November 2019

2019-11-02T18:04:44Z

Dan Tobias at 18:03, 2 November 2019

2019-11-02T18:03:44Z

Dan Tobias at 18:02, 2 November 2019

2019-11-02T18:02:56Z

Dan Tobias at 15:50, 2 November 2019

2019-11-02T15:50:14Z

Dan Tobias: Created page with "{{FormatInfo |formattype=electronic |subcat=Encryption |released=1993 }} '''Doom cheat code encryption''' was used in the original 1993 version of Doom to make the cheat codes..."

2019-11-02T15:05:15Z

Created page with "{{FormatInfo |formattype=electronic |subcat=Encryption |released=1993 }} '''Doom cheat code encryption''' was used in the original 1993 version of Doom to make the cheat codes..."

New page

{{FormatInfo
|formattype=electronic
|subcat=Encryption
|released=1993
}}
'''Doom cheat code encryption''' was used in the original 1993 version of Doom to make the cheat codes a little harder for hackers to find, so they didn't appear in the raw binary code as plain [[ASCII]] characters. Twitter user [https://twitter.com/Foone @Foone] described it in a 2019 thread.

This low-grade encryption is done by shifting the bits of 8-bit numbers (which can represent single ASCII characters) which reverses the order of the bits except for those representing 4 and 32. The shifted values are stored in a lookup table in the Doom program.

== Links ==
* [https://threadreaderapp.com/thread/1189249817492557826.html Twitter thread unrolled]

[[Category:Game data files]]

← Older revision		Revision as of 11:46, 13 January 2023
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	[[Category:Game data files]]		[[Category:Game data files]]
	[[Category:id Software]]		[[Category:id Software]]
		+	[[Category:DOOM (Game)]]

@@ Line 31: / Line 31: @@
 :[[File:Doom-cheat-code-encryption-03.png]]
-The thread goes on with more discussion of how they were used and discovered. It's worthwhile reading for people into this sort of trivia.
+The thread goes on with more discussion of how these codes were used and discovered. It's worthwhile reading for people into this sort of trivia.
 == Links ==

@@ Line 29: / Line 29: @@
 :Well, in m_cheat.c, it's used to build a lookup table which has all the values pre-encrypted, so it can quickly look them up later. Then, when you press a key, it translates it through this table:
-:[[File:Doom-cheat-code-encryption-02.png]]
+:[[File:Doom-cheat-code-encryption-03.png]]
 The thread goes on with more discussion of how they were used and discovered. It's worthwhile reading for people into this sort of trivia.

@@ Line 26: / Line 26: @@
 :[[File:Doom-cheat-code-encryption-02.jpg]]
-The thread goes on to describe the lookup table used to find these values, and the cheat codes embedded in encrypted form, and more discussion of how they were used and discovered. It's worthwhile reading for people into this sort of trivia.
+:So, how is this code used?
 == Links ==

@@ Line 10: / Line 10: @@
 == Details ==
-As described by @Foone, who has [https://twitter.com/Foone/status/1190656026342637569 allowed his descriptions to be released as CC0] so they can be used here:
+As described by @Foone, who has [https://twitter.com/Foone/status/1190656026342637569 allowed these descriptions to be released as CC0] so they can be used here:
 :So Doom (1993) has a neat bit of encryption in it. It's not very strong encryption, but it's still encryption.

@@ Line 19: / Line 19: @@
 :It's taking an 8-bit number and shifting around some of the bits.
-[[File:Doom-cheat-code-encryption-01.png]]
+:[[File:Doom-cheat-code-encryption-01.png]]
 :If you diagram out what's happening, it makes slightly (BUT ONLY SLIGHTLY) more sense.
-It kinda looks like they started with a a "reverse the order of these bits" function but then switched it so the 4 and 32 don't get switched, they just go straight through.
+:It kinda looks like they started with a a "reverse the order of these bits" function but then switched it so the 4 and 32 don't get switched, they just go straight through.
-[[File:Doom-cheat-code-encryption-02.jpg]]
+:[[File:Doom-cheat-code-encryption-02.jpg]]
 The thread goes on to describe the lookup table used to find these values, and the cheat codes embedded in encrypted form, and more discussion of how they were used and discovered. It's worthwhile reading for people into this sort of trivia.

@@ Line 4: / Line 4: @@
 |released=1993
 }}
-'''Doom cheat code encryption''' was used in the original 1993 version of Doom to make the cheat codes a little harder for hackers to find, so they didn't appear in the raw binary code as plain [[ASCII]] characters. Twitter user [https://twitter.com/Foone @Foone] described it in a 2019 thread.
+'''Doom cheat code encryption''' was used in the original 1993 version of Doom to make the cheat codes a little harder for hackers to find, so they didn't appear in the raw binary code as plain [[ASCII]] characters. (Of course, the hackers found them anyway.) Twitter user [https://twitter.com/Foone @Foone] described it in a 2019 thread.
 This low-grade encryption is done by shifting the bits of 8-bit numbers (which can represent single ASCII characters) which reverses the order of the bits except for those representing 4 and 32. The shifted values are stored in a lookup table in the Doom program.
 == Links ==

← Older revision		Revision as of 15:50, 2 November 2019
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	[[Category:Game data files]]		[[Category:Game data files]]
		+	[[Category:id Software]]