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Difference between revisions of "Security Fusings"
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== Board Identifiers == |
== Board Identifiers == |
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| − | Board identifiers are enforced by pulling several pins on the BGA low or high depending on the state of security needed. For example, the device configuration [[ |
+ | Board identifiers are enforced by pulling several pins on the BGA low or high depending on the state of security needed. For example, the device configuration [[N94AP]] is set by pulling the pins to set the board ID: "0b1000" or 0x8. This measure saves costs by allowing Apple to reuse the same processor die with a specified ECID, but they can change the motherboard if necessary. |
== "Fuses" == |
== "Fuses" == |
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| − | These so-called "fuses" are actually fixed resistors on the motherboard. |
+ | These so-called "fuses" are actually fixed resistors on the motherboard, however, if authorized to do so, a Production fused device can have the same privileges as a Development fused device by "demoting" the [[Application Processor]]. |
Revision as of 17:46, 2 September 2017
A common misconception is that iDevices enforce certain flags in their bootloaders when certain "fuses" are "blown".
Processor Security
Processor security flags are enforced by pulling several pins on the BGA low or high depending on the state of security needed. The same is done for board configuration. For example, the device security state is set to 0000 by removing all resistors. This is the PVT configuration.
Board Identifiers
Board identifiers are enforced by pulling several pins on the BGA low or high depending on the state of security needed. For example, the device configuration N94AP is set by pulling the pins to set the board ID: "0b1000" or 0x8. This measure saves costs by allowing Apple to reuse the same processor die with a specified ECID, but they can change the motherboard if necessary.
"Fuses"
These so-called "fuses" are actually fixed resistors on the motherboard, however, if authorized to do so, a Production fused device can have the same privileges as a Development fused device by "demoting" the Application Processor.
