LG GB110, Service Manual

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3.1.10 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 X-GOLDTM102 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 X-GOLDTM102 chip has its
own fused ID.
• Harware support of SHA1 algorithm to reduce the booting time.
Further details on the X-GOLDTM102 security concept are not publicly documented.
GSM Cipher Unit
This unit on the TEAKlite bus calculates the GSM/EDGE encryption keystream and the
GSM/EDGE decryption
keystream. It implements the following algorithms: A5/1, A5/2, and A5/3.
3.1.11 Asynchronous Operation Mode Concept
The X-GOLDTM102 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.