LG GB108, Service Manual

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3.1.15 On-Chip Security Concept
Secure boot is based on a public/private key approach. Flash images that are not signed with the
private key during phone manufacture cannot be loaded. Verification of the Flash code is done
with the public key. The public key as well as hash and verify algorithms are stored in the ROM,
which ensures a hardware secured boot procedure.
The following security features are supported:
• Prevention of illegal Flash programming
• Flash programming makes use of the E-GOLDvoice ID for personalization checks with IMEI and
SIM-lock protection
The security features use the following mechanism:
• Boot ROM flow:
– Controls the boot transition to external flash
– Controls the flash update
• Flash tied to the individual chip via an ID using e-fuses, that is, each E-GOLDvoice chip has its
own fused ID.
Further details on the E-GOLDvoice security concept are not publicly documented.
3.1.16 Asynchronous Operation Mode Concept
The E-GOLDvoice can operate in either:
• The traditional synchronous mode with the 26 MHz system clock synchronized on the base
station
• A special asynchronous mode (XO concept).
In the asynchronous mode the 26 MHz clock input is not synchronized with the base station; the
residual frequency offset is compensated in the digital signal processing domain. This processing
includes frequency and timing compensation of the baseband and voiceband signals.