S08单片机的安全性－已解决

teclimber

如果一个S08单片机我启用了它的安全性状态，也就是SEC=00,01,11后。我知道芯片上的调试模块不起作用了。那程序中我还可以操作芯片内的flash吗？还可以进行读写和擦除吗？
另外，可以通过后门密钥来解除安全状态，看手册上说，要向NVBACKKEY写入密钥，如果我的程序中又启用了flash的块保护功能，那是不是就无法向NVBACKKEY写入密钥了?那就无法通过后门密钥解除安全状态了？

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FSL_TICS_ZHJUN

 
>>如果一个S08单片机我启用了它的安全性状态，也就是SEC=00,01,11后。我知道芯片上的调试模块不起作用了。那程序中我还可以操作芯片内的flash吗？还可以进行读写和擦除吗？
调试模块不起作用了, 但程序照常运行. 如果程序中有读写操作, 就会正常执行.
>>另外，可以通过后门密钥来解除安全状态，看手册上说，要向NVBACKKEY写入密钥，如果我的程序中又启用了flash的块保护功能，那是不是就无法向NVBACKKEY写入密钥了?那就无法通过后门密钥解除安全状态了？
是的. 看datasheet说明
"The backdoor comparison key (NVBACKKEY through NVBACKKEY+7) is located in FLASH memory locations in the nonvolatile register space so users can program these locations just as they would program any other FLASH memory location. The nonvolatile registers are in the same 512-byte block of FLASH as the reset and interrupt vectors, so block protecting that space also block protects the backdoor comparison key. Block protects cannot be changed from user application programs, so if the vector space is block protected, the backdoor security key mechanism cannot permanently change the block protect, security settings, or the backdoor key."

teclimber

回复第 2 楼 于2013-07-09 13:28:04发表:
 
>>如果一个S08单片机我启用了它的安全性状态，也就是SEC=00,01,11后。我知道芯片上的调试模块不起作用了。那程序中我还可以操作芯片内的flash吗？还可以进行读写和擦除吗？
调试模块不起作用了, 但程序照常运行. 如果程序中有读写操作, 就会正常执行.
>>另外，可以通过后门密钥来解除安全状态，看手册上说，要向NVBACKKEY写入密钥，如果我的程序中又启用了flash的块保护功能，那是不是就无法向NVBACKKEY写入密钥了?那就无法通过后门密钥解除安全状态了？
是的. 看datasheet说明
"The backdoor comparison key (NVBACKKEY through NVBACKKEY+7) is located in FLASH memory locations in the nonvolatile register space so users can program these locations just as they would program any other FLASH memory location. The nonvolatile registers are in the same 512-byte block of FLASH as the reset and interrupt vectors, so block protecting that space also block protects the backdoor comparison key. Block protects cannot be changed from user application programs, so if the vector space is block protected, the backdoor security key mechanism cannot permanently change the block protect, security settings, or the backdoor key."
 

非常感谢。

FSL_TICS_ZHJUN

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