LTE  Module  Series 
                                          SC20  Secure  Boot  User  Guide 
 
SC20_Secure_Boot_User_Guide   Confidential / Released                           6 / 15 
 
 
 
1   Introduction   
 
This document mainly introduces how to use the secure boot function of Quectel SC20 module.   
 
Secure boot refers to the boot up sequence that establishes a trusted platform for secure applications. It 
starts as an immutable sequence that validates the origin of the code using cryptographic authentication 
so only authorized software can be executed. The boot up sequence places SC20 in a known security 
state and protects it against binary manipulation of software and reflashing attacks. 
 
A secure boot system adds cryptographic checks to each stage of the boot up process. This process 
asserts the authenticity of all secure software images that are executed by SC20. The additional check 
prevents  any  unauthorized  or  maliciously  modified  software  from  running  on  SC20.  Secure  boot  is 
enabled through a set of hardware fuses. For the code to be executed, it must be signed by the trusted 
entity identified in the hardware fuses. 
 
The flow to enable secure boot: 
 
1.  Configure OEM Key. The new keys can be used to sign images and generate sec.dat 
2.  Generate secure images, download signed images (use fastboot or QFIL tool)   
3.  Generate sec.dat and download it to SC20. Once secure boot fuses are blown, the device cannot 
use other keys.