Unsigned code
Encyclopedia
Unsigned code refers to an application which has not been signed with the secret key
required for it to load on a console
.
In the video game console business, most console games have to be signed with a secret key designed by the console maker or the game will not load on the console. There are several methods to get unsigned code to execute which include software exploits
, the use of a modchip
, a technique known as the swap trick
or running a softmod
.
It may not initially seem obvious why simply copying a signed application onto another DVD does not allow it to boot. On the Xbox
, the reason for this is that the Xbox executable file (XBE) contains a media-type flag, which specifies the type of media that the XBE is boot
able from. On nearly all Xbox software, this is set such that the executable will only boot from factory produced discs so simply copying the executable to burnable media is enough to stop the execution of the software.
However, since the executable is signed, simply changing the value of the flag is not possible as this alters the signature of the executable causing it to fail validation when checked.
Key (cryptography)
In cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would produce no useful result. In encryption, a key specifies the particular transformation of plaintext into ciphertext, or vice versa...
required for it to load on a console
Handheld game console
A handheld game console is a lightweight, portable electronic device with a built-in screen, game controls and speakers. Handheld game consoles are run on machines of small size allowing people to carry them and play them at any time or place...
.
In the video game console business, most console games have to be signed with a secret key designed by the console maker or the game will not load on the console. There are several methods to get unsigned code to execute which include software exploits
Exploit (computer security)
An exploit is a piece of software, a chunk of data, or sequence of commands that takes advantage of a bug, glitch or vulnerability in order to cause unintended or unanticipated behavior to occur on computer software, hardware, or something electronic...
, the use of a modchip
Modchip
A modchip is a small electronic device used to modify or disable built-in restrictions and limitations of computers, specifically videogame consoles...
, a technique known as the swap trick
Swap Magic
Swap Magic is a disc which allows users to play backed-up, copied, or foreign PlayStation 2 games on their PlayStation 2. Swap Magic is legal in the United States under the Digital Millennium Copyright Act....
or running a softmod
Softmod
A softmod is a method of using software to modify the intended behaviour of hardware, such as video cards, sound cards, or game consoles in a way that can overcome restrictions of the firmware, or install custom firmware.-Video card softmods:...
.
It may not initially seem obvious why simply copying a signed application onto another DVD does not allow it to boot. On the Xbox
Xbox
The Xbox is a sixth-generation video game console manufactured by Microsoft. It was released on November 15, 2001 in North America, February 22, 2002 in Japan, and March 14, 2002 in Australia and Europe and is the predecessor to the Xbox 360. It was Microsoft's first foray into the gaming console...
, the reason for this is that the Xbox executable file (XBE) contains a media-type flag, which specifies the type of media that the XBE is boot
Boot
A boot is a type of footwear but they are not shoes. Most boots mainly cover the foot and the ankle and extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is clearly distinguishable from the rest of the sole, even if the two are made of one piece....
able from. On nearly all Xbox software, this is set such that the executable will only boot from factory produced discs so simply copying the executable to burnable media is enough to stop the execution of the software.
However, since the executable is signed, simply changing the value of the flag is not possible as this alters the signature of the executable causing it to fail validation when checked.
See also
- Digital signatureDigital signatureA digital signature or digital signature scheme is a mathematical scheme for demonstrating the authenticity of a digital message or document. A valid digital signature gives a recipient reason to believe that the message was created by a known sender, and that it was not altered in transit...
- iOS jailbreaking
- PlayStation Portable homebrewPlayStation Portable homebrewPlayStation Portable homebrew refers to the process of using exploits and hacks to execute unsigned code on the PlayStation Portable .-History of homebrew:...
- Privilege escalationPrivilege escalationPrivilege escalation is the act of exploiting a bug, design flaw or configuration oversight in an operating system or software application to gain elevated access to resources that are normally protected from an application or user...
- Rooting (Android OS)Rooting (Android OS)Rooting is a process that allows users of mobile phones and other devices running the Android operating system to attain privileged control within Android's Linux subsystem with the goal of overcoming limitations that carriers and manufacturers put on some devices...
- Symbian OS#Bypassing platform security