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Turnkey operates VisualSign parser instances in AWS Nitro Enclaves, providing transaction parsing with attestation verification without requiring you to manage enclave infrastructure.

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Prerequisites

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Integration overview

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Attestation verification

Every parse response carries an AWS Nitro attestation document. To trust the parsed output you must:
  1. Verify the attestation’s certificate chain back to the AWS Nitro root CA.
  2. Check the document’s PCR values against an allowlist you control.
  3. Verify the parser’s ECDSA signature over the parsed payload using the public key from the attestation.
See Attestation Verification for implementation details of all three steps. The remainder of this page covers (2) — specifically, how to obtain the PCR values you should put in your allowlist.

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PCR allowlist values

The PCRs are determined by the qos enclave runtime version Turnkey has deployed (currently TVC 0.12.0, qos commit 4371d44e672a1322d15ef929cfd32169ebb0bd0f). You can reproduce them locally from that qos rev — never trust an externally supplied PCR file without verifying it.

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Generating PCRs from source

The scripts/extract-nitro-pcrs.sh tool in this repo clones tkhq/qos at the deployment rev declared in src/Cargo.toml, builds qos_enclave, and extracts /nitro.pcrs:
The deployment rev lives in a marker comment in src/Cargo.toml:
This is distinct from the rev = "..." on each qos_* crate in the same file, which pins the qos library code that parser_app compiles against and does not affect PCRs. To audit a prospective deployment bump before updating the marker, pass --rev explicitly:

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Prerequisites

  • Docker 26+
  • Git and GNU Make
  • ~8 GB of free RAM and ~15 GB of free disk (StageX base images, a clean cargo compile, and the qos OCI output).

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Options

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How it works

  1. Read the rev — the script extracts a 40-character hex from the # qos-deployment-rev = ... line in src/Cargo.toml. If --rev is supplied it bypasses this step.
  2. Check out qos — clones tkhq/qos into the work dir and checks out the rev. If --qos-dir points at an existing clone whose origin is the upstream tkhq/qos URL and whose HEAD already matches the rev, the script reuses it; if the origin differs the script refuses to touch the directory.
  3. Build qos_enclave — runs make out/qos_enclave/index.json inside the qos checkout. This is qos’s deterministic StageX-based build: it produces a nitro.eif and nitro.pcrs via eif_build and bakes them into the OCI image. The full pipeline lives in qos’s qos_enclave Containerfile.
  4. Extract nitro.pcrs — runs the pinned skopeo image (as your host user, so the staging files clean up) to convert the OCI directory output to a docker-archive tar, loads it under a unique per-run tag, copies /nitro.pcrs out of a freshly created container, and removes both the container and the image on exit.

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What the PCRs measure

PCR0 and PCR1 measure the Nitro EIF and kernel, and PCR2 measures the boot ramdisk that contains qos’s init binary. The parser_app binary is loaded into qos at runtime over vsock and is not part of these PCR measurements — its integrity is established separately via the qos manifest, which is covered at Level 3 attestation. PCR3 in a live attestation measures the AWS IAM role and is intentionally absent from nitro.pcrs.

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Cross-checking against a live prod attestation

You can confirm the locally built PCRs match what the production enclave actually serves by fetching a fresh attestation through visualsign-turnkeyclient.
If both sets of PCR0/PCR1/PCR2 hex values match, the local build reproduces the deployed runtime byte for byte.

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Reproducibility

The qos build is deterministic. Running the script twice should produce byte-identical nitro.pcrs files. Pass --qos-dir to the second run so the cargo and docker layer caches are reused — the second build should be a no-op:
If the diff is empty, the build reproduced.

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API reference

The hosted API uses the same gRPC interface as self-hosted deployments. See gRPC API Reference for message formats and examples.

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Support