Exclusive Chip ID
Encyclopedia
An Exclusive Chip ID, or ECID is a 16-digit Hexadecimal
number used to uniquely identify Apple iOS devices.
Use in Software Authentication=
The ECID of a device is used by Apple, in combination with a hashcode
of the firmware as a challenge key in a challenge-response authentication
protocol. This authentication is done in order to perform digital signing
on iOS software for the iPhone 3GS
and later devices. The response signature is known as an SHSH blob
, and is required in order to perform a software restore on a given iDevice
.
Discovery=
A device's ECID cannot be obtained from the Settings menu of the device. Indirect methods can be applied to force the device into disclosing its ECID. For example, the device can be placed in recovery mode and then queried while in that state from a connected Macintosh computer.
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
number used to uniquely identify Apple iOS devices.
Use in Software Authentication=
The ECID of a device is used by Apple, in combination with a hashcode
Cryptographic hash function
A cryptographic hash function is a deterministic procedure that takes an arbitrary block of data and returns a fixed-size bit string, the hash value, such that an accidental or intentional change to the data will change the hash value...
of the firmware as a challenge key in a challenge-response authentication
Challenge-response authentication
In computer security, challenge-response authentication is a family of protocols in which one party presents a question and another party must provide a valid answer to be authenticated....
protocol. This authentication is done in order to perform digital signing
Digital signature
A 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...
on iOS software for the iPhone 3GS
IPhone 3GS
-Camera:The iPhone 3GS features an improved 3 megapixel camera manufactured by OmniVision. In addition to the higher megapixel count, it also features auto-focus, auto white balance and auto macro and is capable of capturing VGA video...
and later devices. The response signature is known as an SHSH blob
SHSH blob
SHSH blobs is a Hash signature system made by Apple inc. to prevent software downgrades on iPhones, iPads and iPod touches meant for Jailbreaking. An SHSH is created by an SHSH formula with 3 or 4 TSS keys- The device , the firmware signed SHSH blobs is a Hash signature system (Signature HaSH...
, and is required in order to perform a software restore on a given iDevice
IDevice
iDevice in its widest sense, is an unofficial general term that can refer to any mobile electronic devices marketed by Apple Inc. that start with "i" or more specifically any mobile devices that use the iOS operating system, which includes:* iPad* iPhone...
.
Discovery=
A device's ECID cannot be obtained from the Settings menu of the device. Indirect methods can be applied to force the device into disclosing its ECID. For example, the device can be placed in recovery mode and then queried while in that state from a connected Macintosh computer.