Elastic Compute Service:Disk Measurement and Encryption Protection for Confidential Computing Instances

Step 1: Prepare a trusted environment

The trusted environment must meet the following conditions:

• Alibaba Cloud Linux 3 operating system: The CryptPilot tool for creating confidential system disks depends on Alibaba Cloud Linux 3.

• Public IP address enabled: The confidential computing instance must access the Trustee server to obtain the decryption key during startup.

• Sufficient space: The required space depends on the size of the system disk image file that you want to create. We recommend that your environment has more than 40 GiB of free space.

Step 2: Create a confidential system disk image

Step 3: Import the custom image and create a confidential instance

1. Upload the custom image to OSS.

   Upload the local image file to OSS and obtain the file URL. For more information, see Upload files.

2. Import the custom image.

   When you import the custom image, Boot Mode must be set to UEFI.

   

3. After the image is successfully imported, go to the image details page and set the NVMe driver to Enabled.

   

Step 4: Use the imported custom image to create a confidential computing instance

1. Use the imported custom image to create a TDX confidential computing instance or a heterogeneous confidential computing instance.

   When you create the instance, take note of the following parameters:

   • Image: Select the imported custom image and select Confidential VM.

     

   • Public IP Address: Select Assign Public IPv4 Address to enable your instance to access the Trustee service and obtain the key through remote attestation.

   • Logon Credentials: Select Key Pair.

     Confidential system disks created with CryptPilot do not currently support password-based logon.

2. (Optional) If you have deployed the Trustee service, add an inbound rule in the security group of the Trustee instance to allow access to port 8081 from the public IP address of the confidential instance.

   

3. Restart the confidential computing instance.

4. Connect to the confidential computing instance using the Workbench terminal.

   If you can connect to the instance, the instance can access the Trustee service and obtain the key through remote attestation.

Step 5: (Optional) Register reference values in the Trustee service

If you have configured Trustee as the key storage backend, the instance sends a request to the Trustee service during startup to obtain the disk decryption key. The Trustee service verifies the instance environment through remote attestation to check whether it is running in a TEE instance. On top of that, if you also want to verify the running image, you must first register the reference values of the image in Trustee.

1. Use CryptPilot to calculate the reference values of the confidential system disk image and save them to reference-value.json.

   sudo cryptpilot-fde-host show-reference-value --disk ./confidential-disk.qcow2 | tee ./reference-value.json

   The following is an example output, where 466713bf9b2dacca6cd15ff4acd050712e29b4164628e01bd2495411766f36d7ba4560f62537926cf16e08480f1c1804 is the reference value of the image:

2. Import the reference values into the Trustee service.

   provenance=$(cat ./reference-value.json | base64 --wrap=0)
   cat << EOF > ./register-request.json
   {
       "version" : "0.1.0",
       "type": "sample",
       "payload": "$provenance"
   }
   EOF
   
   rvps-tool register --path ./register-request.json

Hardening tool description

To simplify the hardening process, we provide the cryptpilot-enhance tool, which integrates best practices for image security hardening.

cryptpilot-enhance supports two hardening modes:

• full: Full hardening. Removes the SSH service and enforces the strictest access control.

• partial: Partial hardening. Retains the SSH service but enforces key-based authentication. Suitable for production environments that require remote maintenance.

The hardening includes the following items:

Step 1: Prepare the environment

1. Create a confidential computing instance.

   Only TDX confidential instances or heterogeneous confidential instances are supported.

2. Connect to the confidential computing instance remotely.

   For more information, see Log on to a Linux instance using Workbench.

3. Install CryptPilot.

   sudo yum install -y cryptpilot-crypt

Step 2: Create and mount a cloud disk

1. Create an empty data disk to be encrypted.

2. Attach the created data disk to the ECS instance.

3. Initialize the data disk.

   When initializing the data disk, create only partitions and file systems without mounting the file system. The file system must be mounted after encryption.

4. View the attached disk and partition information.

5. lsblk

   The output shows that the current ECS instance has two cloud disks attached:

   • /dev/nvme0n1: The existing system disk.

   • /dev/nvme1n1: The newly added data disk, with 2 new empty partitions (/dev/nvme1n1p1 and /dev/nvme1n1p2).

   

Step 3: Create a volume with an ext4 file system

1. First, you need to write a configuration file /etc/cryptpilot/volumes/data0.toml. This file defines a data volume named data0.

   Note

   The configuration file uses the TOML format. The file name can be any text file ending with .toml and is not required to match the volume name.

   The following are some typical configuration examples for different scenarios. Modify the configuration fields as needed.

   Temporary volume

   # Volume configuration
   dev = "/dev/nvme1n1p1"    # Specify the block device, i.e., the empty partition of the cloud disk. In this example, /dev/nvme1n1p1 uses the first partition of the data disk.
   volume = "data0"          # Specify the volume name. In this example, it is named data0.
   auto_open = false         # true means the volume opens automatically on system startup; false means manual opening is required.
   makefs = "ext4"           # Specify the file system type to create. In this example, ext4.
   integrity = true          # true enables data integrity support; false disables it.
   
   # Key configuration
   [encrypt.otp]             # Specify the key storage type. Here, one-time password (OTP) is selected.

   Persistent volume (using Trustee)

   # Volume configuration
   dev = "/dev/nvme1n1p2"        # Specify the block device, i.e., the empty partition of the cloud disk. In this example, /dev/nvme1n1p2 uses the second partition of the data disk.
   volume = "data0"              # Specify the volume name. In this example, it is named data0.
   auto_open = false             # true means the volume opens automatically on system startup; false means manual opening is required.
   makefs = "ext4"               # Specify the file system type to create. In this example, ext4.
   integrity = true              # true enables data integrity support; false disables it.
   
   # Key configuration (retrieved from Trustee KBS)
   [encrypt.kbs]
   kbs_url = "http://<trustee-ip>:8081/api"               # Replace <trustee-ip> with the public IP address of the Trustee instance
   key_uri = "kbs:///default/local-resources/data0"       # The resource URI for the data0 volume key stored in KBS

   Persistent volume (using Alibaba Cloud KMS)

   # Volume configuration
   dev = "/dev/nvme1n1p2"        # Specify the block device, i.e., the empty partition of the cloud disk. In this example, /dev/nvme1n1p2 uses the first partition of the data disk.
   volume = "data0"              # Specify the volume name. In this example, it is named data0.
   auto_open = false             # true means the volume opens automatically on system startup; false means manual opening is required.
   makefs = "ext4"               # Specify the file system type to create. In this example, ext4.
   integrity = true              # true enables data integrity support; false disables it.
   
   # Key configuration
   [encrypt.kms]                 # Specify the key storage type. Here, Key Management Service (KMS) is selected.
   secret_name = "confidential_cloud_disk_passphrase"   # The name of the secret stored in the KMS instance, i.e., confidential_cloud_disk_passphrase in the example above.
   # Content of the application identity credential file (clientKey_****.json)
   client_key = '''
   {
     "KeyId": "KAAP.b183152a-c3bf-43ae-9399-a101607b****",
     "PrivateKeyData": "MIIJ0wIBAzCCCZ8GCSqGSIb3DQE****"
   }
   '''
   client_key_password = "258372e962f5204ce648bc66243f****"    # Content of the credential password file (clientKey_****_Password.txt)
   kms_instance_id = "kst-bjj67d004a85ykq80****"               # KMS instance ID
   # Content of the KMS instance CA certificate file (PrivateKmsCA_kst-******.pem)
   kms_cert_pem = """
   -----BEGIN CERTIFICATE-----
   MIIDuzCCAqOgAwIBAgIJALTKwWAjvbMiMA0GCSqGSIb3DQEBCwUAMH****
   -----END CERTIFICATE-----
   -----BEGIN CERTIFICATE-----
   MIID3zCCAsegAwIBAgIJAO8qnQyTy8/kMA0GCSqGSIb3DQEBCwUAMH****
   -----END CERTIFICATE-----
   """

2. View the volume status.

   sudo cryptpilot-crypt show data0

   You can see the configuration information of the data0 volume:

   • Initialized column: Shows whether the volume needs initialization. Temporary volumes do not need initialization, while persistent volumes do.

   • Opened column: Shows that the volume is not open.

     

3. Initialize the volume.

   sudo cryptpilot-crypt init data0

4. Open the volume.

   sudo cryptpilot-crypt open data0

5. Check the virtual device of the volume.

   sudo file -Ls /dev/mapper/data0

   After the volume is opened, a virtual block device is created at the path: /dev/mapper/<volume_name>.

   

5. Mount the file system and check the mount result.

   1. Mount the data0 volume to the /mnt/data0 path.

      sudo mkdir -p /mnt/data0
      sudo mount -t ext4 /dev/mapper/data0 /mnt/data0

   2. Check the mount result.

      mount | grep data0
      ls -la /mnt/data0/

      The following output indicates that the volume was successfully mounted with an empty ext4 file system.

      

6. Close the volume.

   Important

   • This example uses the one-time password (OTP) model. After the volume is closed, the confidential data stored in it is permanently lost.

   • Before closing the volume, stop all business processes that are reading from or writing to the volume, unmount the file system on the volume, and ensure the volume is not in use.

   1. Unmount the file system.

      sudo umount /mnt/data0

   2. Close the volume.

      sudo cryptpilot-crypt close data0

      

Step 4: Configure the volume to open automatically on startup

1. Modify the configuration file.

   For volumes that need to open automatically, change the auto_open field value to true in the configuration file.

2. (Conditional) For persistent volumes, you must manually run sudo cryptpilot-crypt init <volume_name> to initialize the volume before it can be opened automatically on startup.

3. Start and enable the cryptpilot service to start on boot.

   Important

   After each modification of the cryptpilot configuration, you must start and enable the cryptpilot service to ensure the auto-open volume feature takes effect.

   sudo systemctl enable --now cryptpilot.service

4. Restart the instance.

5. View the volume status.

   sudo cryptpilot-crypt show

   The following output indicates that the volume was opened automatically.