Attestation

Attestation is a process that starts by default at virtual instance creation, ensures that the virtual server instance image is indeed built by IBM, and that it was not modified. This process also provides information and allows validation of any data that is provided to the instance at the time of deployment.

When you create a virtual server instance by using the IBM Hyper Protect Container Runtime (HPCR) image, the image uses an initial file system that is protected by encryption and signed by IBM Secure Execution (SE). For more information, see Confidential computing with LinuxONE. To know more about the attestation process, see this video.

The boot process creates a unique root disk encryption key to ensure protection of the root disk. To perform attestation, the virtual server instance image contains an attestation-signing key and the hash of the root partition at build time. The boot process validates the root partition. If the hash of the root partition does not match, the boot process does not continue because it assumes that the image was modified before boot. The attestation signing key is a random RSA 4 K key that is signed by an IBM root key that is maintained in Hyper Protect Crypto Services. The IBM root key is signed by Digicert.

During deployment of the virtual server instance, an attestation record is created. It contains hashes of the following items:

• The original base image
• The root partition at the moment of the first boot
• The root partition at build time
• The cloud initialization options

The attestation record is signed by the attestation key. As an extra protection layer, you can provide a public key during deployment, against which the attestation record is encrypted. The hash of this public key is added to the attestation record to ensure that the record can be viewed only by the compliance authority, and the expected authority can be easily identified through that hash.

Before you upload any workload to your instance, you need to validate the attestation record. After an instance is created, you can validate the attestation record within the created instance. Your instance must have access to the /var/hyperprotect directory. If so, follow these procedures:

• The attestation record is signed by the attestation signing key.
• The attestation signing key can be confirmed by the IBM intermediate certificate. The IBM intermediate certificate is signed by DigiCert, which is proven by the root certificate of DigiCert, thus completing the chain of trust.

The encryption and attestation certificates are signed by the IBM intermediate certificate and this has been signed by the IBM Digicert intermediate cert (which in turn is signed by DigiCert Trusted Root G4). For more information about the certificates, see DigiCert Trusted Root Authority Certificates.

Use the following procedure to validate the attestation record and hashes:

• Obtain the attestation record se-checksums.txt and the signature file se-signature.bin from your IBM Hyper Protect Virtual Servers instance. To do so, you can implement your container to provide the attestation record and the signature file. The attestation record and the signature file are made available to your container in the /var/hyperprotect directory.

• Get the IBM attestation certificate that is a part of the image TAR file.

• Validate the attestation certificate by following the instructions here.

• Extract the encryption public key from the encryption certificate by using the following command:

   openssl x509 -pubkey -noout -in ibm-hyper-protect-container-runtime-24.7.1-attestation.crt > contract-public-key.pub
  

• Verify the signature of the attestation record:

  openssl sha256 -verify contract-public-key.pub -signature se-signature.bin se-checksums.txt
  

  Note: Signature verification must be done on a decrypted attestation file.

• You can now use the hashes from the attestation record for validation.

In case you provided a public key for encrypting the attestation record, the following script might help in decrypting the record.

#!/bin/bash
#
# Example script to decrypt attestation document.
#
# Usage:
#   ./decrypt-attestation.sh <rsa-priv-key.pem> [file]
#
# Token Format:
#   hyper-protect-basic.<ENC_AES_KEY_BASE64>.<ENC_MESSAGE_BASE64>


RSA_PRIV_KEY="$1"
if [ -z "$RSA_PRIV_KEY" ]; then
    echo "Usage: $0 <rsa-priv-key.pem>"
    exit 1
fi
INPUT_FILE="${2:-se-checksums.txt.enc}"
TMP_DIR="$(mktemp -d)"
#trap 'rm -r $TMP_DIR' EXIT


PASSWORD_ENC="${TMP_DIR}/password_enc"
MESSAGE_ENC="${TMP_DIR}/message_enc"


# extract encrypted AES key and encrypted message
cut -d. -f 2 "$INPUT_FILE"| base64 -d > "$PASSWORD_ENC"
cut -d. -f 3 "$INPUT_FILE"| base64 -d > "$MESSAGE_ENC"

# decrypt password
PASSWORD=$(openssl pkeyutl -decrypt -inkey "$RSA_PRIV_KEY" -in "$PASSWORD_ENC")


# decrypt message
echo -n "$PASSWORD" | openssl aes-256-cbc -d -pbkdf2 -in "$MESSAGE_ENC" -pass stdin --out se-checksums.txt

In the case of a docker container, the decrypt-attestation.sh file can be accessed by mounting /var/hyperprotect in the docker container. For example,

 volumes:
      - "/var/hyperprotect/:/var/hyperprotect/:ro"

In the case of a Podman container, the decrypt-attestation.sh file can be accessed by mounting /var/hyperprotect in the Podman container. For example,

 volumeMounts:
     - name: attestation
       readOnly: true
       mountPath: /var/hyperprotect:Z,U

/var/hyperprotect
/var/hyperprotect/
|-- cidata
|   |-- meta-data
|   |-- vendor-data
|-- se-checksums.txt
|-- se-signature.bin
|-- se-version
|-- user-data.decrypted

sha256sum <file>

24.7.1
Machine Type/Plant/Serial: 8562/02/4C578
4802242b82dce78d11c4b02129a9b9c1e62598b1cb8073f8e7b097449644bbb4 root.tar.gz
f9940321d043d133ddf2f22cd4794bc56be9d54b2e9c7893a6d6a4813635024c baseimage
41e32bac07e1eac019b40707f1cedf8356830a690108dc35dc07aa160a61a09e /dev/disk/by-label/cidata
6e78289af3fd2d265e0ee06289b46b9692046fa8af0f25711ee11cc6c5b0a45a cidata/meta-data
194d230a7d0d0fa5657a963d21e3291064f988e9df719b4f2b4db4de2746eccd cidata/user-data
ab65daacc8ca30ddbfe2fbdd5a93b8b6f9f92b7145fcae42fc61f4501f361658 cidata/vendor-data
38e1f81c213d93d3ff39a94de47cfebb6f7309528da3249546439c1de7683874 contract:env 
de4178e749c6ab0ee9af8610d0615cfd004d7d488dfdc0d5aa87e0b75fdff7fc contract:envWorkloadSignature 
8bfaf247e3f3936c446de151da1613d2e7e5440ba0d95065e7048e14626f4e2f contract:workload

f9940321d043d133ddf2f22cd4794bc56be9d54b2e9c7893a6d6a4813635024c baseimage

4802242b82dce78d11c4b02129a9b9c1e62598b1cb8073f8e7b097449644bbb4 root.tar.gz

 volumes:
      - "/var/hyperprotect/:/var/hyperprotect/:ro"

 volumeMounts:
     - name: attestation
       readOnly: true
       mountPath: /var/hyperprotect:Z,U