Glossary
Definitions of the terms used in remote attestation and on this site, from attester and verifier to TPM quotes, IMA and confidential VMs. Each definition is one or two sentences; the Concepts page and the specification give the details. The 45 terms are sorted alphabetically; 20 of them also appear as tooltips where the documentation first uses them.
A
- AK
- Attestation key: a key held by the TPM that signs quotes. The verifier pins it at enrollment.
- Attestation result
- In RATS terms, the verifier's report: pass, fail or inconclusive, with the evidence level it rests on.
- Attester
- The component on the machine being checked. It collects facts and reports them; it never decides the result.
C
- Canonical JSON
- The exact bytes the evidence digest covers: no whitespace, object keys sorted by UTF-16 code units, numbers and strings written as ECMAScript JSON.stringify writes them.
- Code injection vector
- A way to load code into a process without changing its files: LD_PRELOAD, NODE_OPTIONS, PYTHONPATH, JAVA_TOOL_OPTIONS, debuggers, ptrace or memfd code. Attestium reports each one.
- Confidential VM
- A virtual machine whose memory the host cannot read, with a launch measurement the CPU signs. AMD SEV-SNP and Intel TDX.
- configfs-tsm
- The Linux interface (/sys/kernel/config/tsm/report, Linux 6.7 and later) through which a confidential VM asks for a SEV-SNP or TDX report over 64 bytes of its choice.
D
- DSSE
- Dead Simple Signing Envelope: signs a payload together with its type. Used by in-toto and Sigstore attestations.
E
- EK
- Endorsement key: the TPM's identity key, certified by its manufacturer.
- Enrollment
- The one-time step that checks a TPM's endorsement key certificate, creates an attestation key in the same TPM and pins it on the verifier.
- Evidence
- The JSON document an attester returns: facts about files, packages, processes, containers and hardware, with no verdicts. Defined by the Attestium specification, version 2.
- Evidence digest
- evidenceDigest: the lowercase hex SHA-256 of the canonical JSON of the evidence without evidenceDigest, tpm, ima and confidential.
- Evidence level
- What backs a result: software evidence, TPM-bound, TPM and IMA, or confidential VM. Report it with every result.
F
- Forced command
- An SSH authorized_keys entry that restricts a key to one command. The verifier's key may run only the attester.
- Fulcio
- Sigstore's certificate authority. It issues short-lived signing certificates for OIDC identities.
I
- IMA
- Integrity Measurement Architecture: the Linux kernel hashes files as they are used, logs each hash and extends PCR 10.
- in-toto
- A framework for signed statements about the steps of a supply chain. GitHub artifact attestations and npm provenance carry in-toto statements.
- Inconclusive
- The state of a check that could not complete, such as an unreadable file or a registry that did not answer. Never treated as passing.
L
- Lockfile
- A file that pins the exact version and hash of every dependency, such as pnpm-lock.yaml, uv.lock, Gemfile.lock, mix.lock or packages.lock.json. The verifier reads it from its own checkout.
M
- Measured boot
- Firmware, bootloader and kernel extend TPM PCRs with hashes of what they load, so a quote with pinned PCR values shows how the machine booted.
- Monitor
- Attestium's optional recorder, built on eBPF with bpftrace, of every program started and file mapped executable between two audits.
N
- Nonce
- A random value the verifier chooses for one request, so that an old answer cannot be replayed.
O
- OCI
- Open Container Initiative: the standard image and registry formats. Manifests and layers are addressed by SHA-256 digest.
P
- PCR
- Platform Configuration Register: a TPM register that can only be extended with a hash. Firmware, bootloader and kernel extend PCRs with what they load.
- Provenance
- A signed statement that links an artifact to the repository, commit and workflow that built it, such as npm provenance or a GitHub artifact attestation.
R
- RATS
- Remote ATtestation procedureS: the IETF architecture (RFC 9334) that defines attester, verifier and relying party.
- Reference
- What the verifier compares a fact with, obtained by the verifier itself: a public commit, a package a lockfile pins, an image layer, an official release, a signed archive or a pinned key.
- Rekor
- Sigstore's public, append-only transparency log of signatures.
- Release manifest
- .attestium-manifest.json at the root of a release deployed without git: the repository, the commit and every file's SHA-256 and mode. CI attests its SHA-256.
- Relying party
- Whoever reads the verifier's result, for example on a status page.
- Remote attestation
- A way for a verifier to check what another machine runs from evidence that machine produces, without trusting the machine's own judgment.
- Reproducible build
- A build that produces the same bytes from the same source, so anyone can confirm a binary came from its claimed source.
- Runtime attestation
- Remote attestation of what a server runs now, after deployment: its files, packages, processes and containers, rather than only how it was built or booted.
S
- SBOM
- Software bill of materials: a list of the components in a piece of software.
- SEV-SNP
- AMD Secure Encrypted Virtualization with Secure Nested Paging: confidential VMs whose launch measurement the AMD chip signs.
- Sigstore
- A public signing service: short-lived certificates from Fulcio tied to an OIDC identity, with signatures logged in Rekor.
- SLSA
- Supply-chain Levels for Software Artifacts: a framework whose provenance describes how, where and from which source an artifact was built.
- Software evidence
- Evidence backed only by the attester's report and the digest. It detects drift and tampering by anyone without root, but whoever controls the attester can forge it.
T
- TDX
- Intel Trust Domain Extensions: confidential VMs whose measurement is signed through Intel's quoting enclave.
- TPM
- Trusted Platform Module: a chip with keys that cannot be exported and registers (PCRs) that can be extended but never set.
- TPM quote
- A TPM signature over selected PCR values and qualifying data chosen by the caller. Attestium's qualifying data is SHA-256(nonce ‖ evidenceDigest).
- TUF
- The Update Framework: signed, versioned metadata for distributing keys and files. Sigstore ships its trusted root with it.
U
- Unexplained file
- A running executable or library that matches no reference. The verifier reports it.
V
- VCEK
- Versioned Chip Endorsement Key: the AMD per-chip key that signs SEV-SNP reports, certified through the ASK to AMD's root.
- Verifier
- The component that runs elsewhere, typically in CI: it sends a nonce, obtains references itself and compares.