Re: Protecting the key in ram.



On Feb 14, 1:54 pm, Mok-Kong Shen <mok-kong.s...@xxxxxxxxxxx> wrote:
Globemaker wrote:
The key can be used from a register during instruction
execution without using RAM.

When the key is read in, wouldn't it pass through RAM?>
M. K. Shen

No. The disk drive has a buffer to hold a 512 byte sector. The
microprocessor can read that hard disk drive buffer without using RAM
or cache. Only if DMA is used (Direct Memory Access) can the RAM be
written to without the CPU reading first. Without DMA and cache
enabled, the CPU can read the hard drive passsword or key into a CPU
register without ever using a RAM. The password can be deleted from
the CPU register after it is used. The Intel Programmers' Reference
Guide tells about the CPU registers that an assembly language program
can access.
.



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