Protected RAM regions can be retained and locked for storing symmetric keys. The CPU cannot access these regions.
After KMU has pushed keys into the protected RAM, PROTECTEDRAMLOCK must be set to Enabled before CRACEN can access and use the keys.
Register PROTECTEDRAMLOCK is a write-once register, and cannot be changed until the next device reset.
The following areas are defined for the protected RAM.
| Protected RAM | ||
|---|---|---|
| Address | End address | Description |
| 0x51810040 | 0x5181005F | AES Protected key 0 |
| 0x51810060 | 0x5181007F | AES Protected key 1 |
| 0x51810080 | 0x5181008F | SM4 Protected key 0 |
| 0x51810090 | 0x5181009F | SM4 Protected key 1 |
| 0x518100A0 | 0x518100AF | SM4 Protected key 2 |
| 0x518100B0 | 0x518100BF | SM4 Protected key 3 |