AES_GCMHRx

AES GCM H Word Register x

  0x9C + x*0x04 [x=0..3] 32 R/W 0x00000000   4 -1
Parent topic: Register Summary

AES GCM H Word Register x

Bit  31 30 29 28 27 26 25 24  
  H[31:24]  
Access  R/W R/W R/W R/W R/W R/W R/W R/W  
Reset  0 0 0 0 0 0 0 0  
Bit  23 22 21 20 19 18 17 16  
  H[23:16]  
Access  R/W R/W R/W R/W R/W R/W R/W R/W  
Reset  0 0 0 0 0 0 0 0  
Bit  15 14 13 12 11 10 9 8  
  H[15:8]  
Access  R/W R/W R/W R/W R/W R/W R/W R/W  
Reset  0 0 0 0 0 0 0 0  
Bit  7 6 5 4 3 2 1 0  
  H[7:0]  
Access  R/W R/W R/W R/W R/W R/W R/W R/W  
Reset  0 0 0 0 0 0 0 0  

Bits 31:0 – H[31:0]: GCM H Word x

GCM H Word x

The four 32-bit H Word registers contain the 128-bit GCM hash subkey Hvalue.

Whenever a new key is written to the AES Key Register, two automatic actions are processed:
  • GCM hash subkey H generation
  • AES_GHASHRx Clear

If the application software requires a specific hash subkey, the automatically-generated H value can be overwritten in AES_GCMHRx. See Key Writing and Automatic Hash Subkey Calculation for details.

Generating a GCM hash subkey H by a write in AES_GCMHRx enables to: