Kcrypt challenger

Kcrypt TPM challenger

With Kairos you can build immutable, bootable Kubernetes and OS images for your edge devices as easily as writing a Dockerfile. Optional P2P mesh with distributed ledger automates node bootstrapping and coordination. Updating nodes is as easy as CI/CD: push a new image to your container registry and let secure, risk-free A/B atomic upgrades do the rest.

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❗	This is experimental!

This is the Kairos kcrypt-challenger Kubernetes Native Extension.

Usage

See the documentation in our website: https://kairos.io/docs/advanced/partition_encryption/.

TPM NV Memory Cleanup

⚠️ DANGER: This command removes encryption passphrases from TPM memory! ⚠️ If you delete the wrong index, your encrypted disk may become UNBOOTABLE!

During development and testing, the kcrypt-challenger may store passphrases in TPM non-volatile (NV) memory. These passphrases persist across reboots and can accumulate over time, taking up space in the TPM.

To clean up TPM NV memory used by the challenger:

# Clean up the default NV index (respects config or defaults to 0x1500000)
kcrypt-discovery-challenger cleanup

# Clean up a specific NV index
kcrypt-discovery-challenger cleanup --nv-index=0x1500001

# Clean up with specific TPM device
kcrypt-discovery-challenger cleanup --tpm-device=/dev/tpmrm0

Safety Features:

• By default, the command shows warnings and prompts for confirmation
• You must type "yes" to proceed with deletion
• Use --i-know-what-i-am-doing flag to skip the prompt (not recommended)

Note: This command uses native Go TPM libraries and requires appropriate permissions to access the TPM device.

Installation

To install, use helm:

# Adds the kairos repo to helm
$ helm repo add kairos https://kairos-io.github.io/helm-charts
"kairos" has been added to your repositories
$ helm repo update                                        
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "kairos" chart repository
Update Complete. ⎈Happy Helming!⎈

# Install the CRD chart
$ helm install kairos-crd kairos/kairos-crds
NAME: kairos-crd
LAST DEPLOYED: Tue Sep  6 20:35:34 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None

# Installs challenger
$ helm install kairos-challenger kairos/kcrypt-challenger

TODO: Implement Selective Enrollment Mode for Attestation Data

Problem Statement

Currently, the TPM attestation system faces operational challenges in real-world deployments:

1. Test Complexity: Tests require manually creating SealedVolumes with complex mock attestation data (EK, AK, PCR values)
2. Upgrade Compatibility: Kernel upgrades change PCR values, causing TPM quarantine and disk inaccessibility
3. Operational Flexibility: No mechanism for operators to reset/update attestation data after TPM replacement, firmware upgrades, or key rotation

Proposed Solution: Selective Enrollment Mode

Implement a "selective enrollment mode" where operators can set specific attestation fields to empty/null values in SealedVolume specs, indicating that the server should:

1. Accept any value for that field during attestation
2. Store the received value for future verification
3. Update the SealedVolume with the learned value

Required Implementation Changes

1. SealedVolume API Enhancement

spec:
  TPMHash: "required-tpm-hash"  # MUST be set for client matching
  attestation:
    ekPublicKey: ""             # Empty = enrollment mode
    akPublicKey: ""             # Empty = enrollment mode  
    pcrValues:
      pcrs:
        "0": ""                 # Empty = enrollment mode for this PCR
        "7": "fixed-value"      # Set = enforce this value
        # "11": omitted         # Omitted = skip verification entirely

2. Server Logic Updates

• Modify verifyAKMatch() to handle empty AK fields as enrollment mode
• Modify verifyPCRValues() to handle empty PCR values as enrollment mode
• Add logic to update SealedVolume specs when learning new values
• Ensure TPM hash is always required and validated for client matching

3. Test Simplification

Replace complex mock attestation data in tests with simple enrollment mode:

# tests/encryption_test.go - remote-static test
spec:
  TPMHash: "computed-from-vm"   # Get from /system/discovery/kcrypt-discovery-challenger
  partitions:
    - label: COS_PERSISTENT
      secret: {name: "static-passphrase", path: "pass"}
  attestation: {}               # Full enrollment mode

Use Cases Solved

1. Static Passphrase Tests: Create Secret + minimal SealedVolume, let TOFU handle attestation
2. Production Manual Setup: Operators set known passphrases + TPM hashes, system learns security data
3. Firmware Upgrades: Set PCR fields to empty to re-learn after BIOS updates
4. TPM Replacement: Set AK field to empty to re-learn after hardware changes
5. Kernel Updates: Omit PCR 11 entirely to avoid quarantine on upgrades

Critical Implementation Notes

• TPM Hash MUST remain mandatory - without it, multiple clients would match the same SealedVolume
• EK verification should remain strict - only AK and PCRs should support enrollment mode
• Add proper logging for enrollment events for audit trails
• Consider rate limiting to prevent abuse of enrollment mode
• Update documentation with operational procedures for each use case

Priority: High

This blocks current test failures and addresses fundamental operational challenges for production deployments.