6,263
edits
Changes
Jump to navigation
Jump to search
Line 581:
Line 581: − +
→Updating keydata
The contents of the keyslot specified in REG_AESKEYCNT can be updated by consecutively writing four words to REG_AESKEYXFIFO (keyX), REG_AESKEYYFIFO(keyY), or REG_AESKEYFIFO (normalkey).
The contents of the keyslot specified in REG_AESKEYCNT can be updated by consecutively writing four words to REG_AESKEYXFIFO (keyX), REG_AESKEYYFIFO(keyY), or REG_AESKEYFIFO (normalkey).
After writing to a keyslot, the keyslot must be selected again(write REG_AESKEYSEL + set REG_AESCNT bit26), even when writing to the same keyslot.
After writing to a keyslot when that same keyslot is already selected via REG_AESKEYSEL, the keyslot must be selected again(write REG_AESKEYSEL + set REG_AESCNT bit26), in order for the AES engine to use the new key-data.
Writing to the key FIFOs with byte writes results in the AES engine converting the byte to a word for setting the key word, with this: word = (byteval) | (byteval<<8) | (byteval<<16) | (byteval<<24). The result is the same regardless of which FIFO register byte was written to.
Writing to the key FIFOs with byte writes results in the AES engine converting the byte to a word for setting the key word, with this: word = (byteval) | (byteval<<8) | (byteval<<16) | (byteval<<24). The result is the same regardless of which FIFO register byte was written to.