[rom_ext] Remove redundant key_save in dice / dice_cwt

The `dice_chain` module now handles saving the issuer key to OTBN DMEM,
rendering these individual `key_save` calls in the `dice` and `dice_cwt`
libraries redundant.

Signed-off-by: Yi-Hsuan Deng <yhdeng@google.com>
Change-Id: I9ea1f54d927ae48ace06e7ba1c0ee5d46a6a6964

Author: sasdf

sw/device/silicon_creator/lib/cert/dice.c

@@ -162,11 +162,6 @@ rom_error_t dice_cdi_0_cert_build(hmac_digest_t *rom_ext_measurement,
 
   HARDENED_RETURN_IF_ERROR(cdi_0_build_cert(&cdi_0_params, cert, cert_size));
 
-  // Save the CDI_0 private key to OTBN DMEM so it can endorse the next stage.
-  HARDENED_RETURN_IF_ERROR(otbn_boot_attestation_key_save(
-      kDiceKeyCdi0.keygen_seed_idx, kDiceKeyCdi0.type,
-      *kDiceKeyCdi0.keymgr_diversifier));
-
   return kErrorOk;
 }
 
@@ -231,11 +226,6 @@ rom_error_t dice_cdi_1_cert_build(
 
   HARDENED_RETURN_IF_ERROR(cdi_1_build_cert(&cdi_1_params, cert, cert_size));
 
-  // Save the CDI_1 private key to OTBN DMEM so it can endorse the next stage.
-  HARDENED_RETURN_IF_ERROR(otbn_boot_attestation_key_save(
-      kDiceKeyCdi1.keygen_seed_idx, kDiceKeyCdi1.type,
-      *kDiceKeyCdi1.keymgr_diversifier));
-
   return kErrorOk;
 }
 

sw/device/silicon_creator/lib/cert/dice_cwt.c

@@ -277,10 +277,6 @@ rom_error_t dice_cdi_0_cert_build(hmac_digest_t *rom_ext_measurement,
   HARDENED_RETURN_IF_ERROR(cwt_dice_chain_entry_build(
       &cwt_dice_chain_entry_params, cert, cert_size));
 
-  // Save the CDI_0 private key to OTBN DMEM so it can endorse the next stage.
-  HARDENED_RETURN_IF_ERROR(otbn_boot_attestation_key_save(
-      kDiceKeyCdi0.keygen_seed_idx, kDiceKeyCdi0.type,
-      *kDiceKeyCdi0.keymgr_diversifier));
   return kErrorOk;
 }
 
@@ -383,11 +379,6 @@ rom_error_t dice_cdi_1_cert_build(
   HARDENED_RETURN_IF_ERROR(cwt_dice_chain_entry_build(
       &cwt_dice_chain_entry_params, cert, cert_size));
 
-  // Save the CDI_1 private key to OTBN DMEM so it can endorse the next stage.
-  HARDENED_RETURN_IF_ERROR(otbn_boot_attestation_key_save(
-      kDiceKeyCdi1.keygen_seed_idx, kDiceKeyCdi1.type,
-      *kDiceKeyCdi1.keymgr_diversifier));
-
   return kErrorOk;
 }