DPU BMC SPDM Attestation via Redfish

The DPU BMC attestation process enables secure verification of device identity and firmware integrity using standardized protocols. This implementation leverages SPDM (Security Protocol and Data Models) over MCTP (Management Component Transport Protocol) to provide remote attestation capabilities via the Redfish API.

Get ComponentIntegrity Collection

            

            
curl -k -u root:'<password>' -H "Content-Type: application/json" -X GET https://<bmc ip>/redfish/v1/ComponentIntegrity
        

This command returns a collection of all attestation targets in the system.

In DPU BMC, the available attestation targets are:

• Bluefield_DPU_IRoT – The BlueField IRoT (Initial Root of Trust), a Platform Security Controller (PSC) that stores measurements related to the Arm and NIC components

• Bluefield_ERoT – The BlueField BMC ERoT (Endpoint Root of Trust), which contains measurements related to the DPU BMC

Get Certificate Chain of Specific Attestation Target

            

            
curl -k -u root:'<password>' -H "Content-Type: application/json" -X GET https://<bmc ip>/redfish/v1/Chassis/<target-id>/Certificates/CertChain
        

This command retrieves the certificate chain for a specific attestation target. The response is a JSON structure containing the entire certificate chain, which can be used to verify the authenticity of the component.

Get Measurements from Attestation Target

            

            
# 1. Request all available measurements
curl -k -u root:'<password>' -H "Content-Type: application/json" -X POST \
  https://<bmc ip>/redfish/v1/ComponentIntegrity/<target id>/Actions/ComponentIntegrity.SPDMGetSignedMeasurements
 
# 2. Request specific measurements
curl -k -u root:'<password>' -H "Content-Type: application/json" -X POST \
  -d '{"SlotId": 0, "MeasurementIndices": [2,5], "Nonce": "d42a0594c5cd5743ee08fe5ec3cf884b1fac4f106879cda98b7d1c51652b04b7"}' \
  https://<bmc ip>/redfish/v1/ComponentIntegrity/HGX_IRoT_NIC_0/Actions/ComponentIntegrity.SPDMGetSignedMeasurements
        

This command retrieves signed measurements from the specified component.

Parameters:

1. Nonce

   • Description: A unique, randomly generated value used to prevent replay attacks.

   • Format: 32-byte (64-character) hexadecimal string.

   • Usage:

     • Must be generated and provided by the client for each request.

     • Ensures that each request is fresh and secure.

2. Certificate Slot ID

   • Description: Indicates which slot contains the certificate chain used for signing.

   • Supported Value: 0

   • Default: 0

   • Note: Only Slot 0 is supported, which holds the NVIDIA certificate chain.

3. Measurement Indices

   • Description: Specifies the measurement indices to request.

   • Format: Array of integers.

   • Default: If omitted, 0xFF is used to request all available measurements.

Handling the Response

This operation is asynchronous and returns a task object rather than the measurement data itself.

Example response:

            

            
{
  "@odata.id": "/redfish/v1/TaskService/Tasks/0",
  "@odata.type": "#Task.v1_4_3.Task",
  "Id": "<id>",
  "TaskState": "Running",
  "TaskStatus": "OK"
}
        

Monitoring Task Progress

Periodically check the task until completion using:

            

            
curl -k -u root:'<password>' -H "Content-Type: application/json" \
  -X GET https://<bmc ip>/redfish/v1/TaskService/Tasks/<id>
        

A completed task appears as

            

            
{
  ...
  "PercentComplete": 100,
  ...
  "TaskState": "Completed",
  "TaskStatus": "OK"
}
        

Get Measurements Response Data

            

            
curl -k -u root:'<password>' -H "Content-Type: application/json" -X GET \
  https://<bmc ip>/redfish/v1/ComponentIntegrity/<target id>/Actions/ComponentIntegrity.SPDMGetSignedMeasurements/data
        

This command retrieves the signed measurement data previously requested via the SPDMGetSignedMeasurements action.

Example output:

            

            
{
  "HashingAlgorithm": "TPM_ALG_SHA_512",
  "SignedMeasurements": "<base64 encoded measurements>",
  "SigningAlgorithm": "TPM_ALG_ECDSA_ECC_NIST_P384",
  "Version": "1.1.0"
}
        

Each time a new Get Measurements command is issued, a Redfish event log entry is generated.

Example entry:

            

            
{
  "@odata.id": "/redfish/v1/Systems/Bluefield/LogServices/EventLog/Entries/<id>",
  "@odata.type": "#LogEntry.v1_15_0.LogEntry",
  "Created": "<date>",
  "EntryType": "Event",
  "Id": "<id>",
  "Message": "Redfish attestation measurements POST request received",
  "Modified": "<date>",
  "Name": "System Event Log Entry",
  "Resolved": false,
  "Severity": "OK"
}