DA-04 · LESSON 06

TEE custody

KEY DEFINITIONS

Terms used in this lesson

TEE: Trusted execution environment: an isolated computing area intended to protect code and secrets while they are in use.
DKG: Distributed key generation: participants create shares of a group key without one party learning the complete secret.
Guardian: A Ducat policy-checking signer that can authorize or reject defined protocol transactions.

Attested enclaves bind code measurements and short-lived sealing keys so shares are finalized, stored, and used inside confidential workloads.

45 min Difficulty 4/5 Not started

VISUAL MODEL

See the whole mechanism before going step by step

Use the diagrams to orient yourself. Then the guided explanation below teaches every part in depth.

4 explanatory views

CONCEPT-SPECIFIC MAP · ducat vaultA Ducat action moves one Bitcoin-anchored vault state to a successorSelect any state to inspect its exact role.

RELATIONSHIP MAPInputs, rule, and outputs

01
PREDECESSORCurrent vault outpoint
The current Bitcoin output anchors collateral and identifies the state being spent.
02
REQUESTTEE custody
The TEE custody workflow proposes one exact action and successor state.
03
POLICYProfile, oracle, signatures
Applicable policy, price evidence, authorization, and transaction shape are checked.
04
BITCOIN SPENDScript-valid transaction
Bitcoin miners and nodes can include only a transaction that satisfies Bitcoin rules.
05
SUCCESSORNew outpoint and state
Ducat validators reconstruct debt, collateral, token, and account changes from the confirmed transaction.

Rule shown: Bitcoin checks the spend; Ducat components independently reconstruct and validate the additional protocol state.

STAGE 1 OF 5PREDECESSOR: Current vault outpoint

The current Bitcoin output anchors collateral and identifies the state being spent.

Governing relationship: Bitcoin checks the spend; Ducat components independently reconstruct and validate the additional protocol state. Complete path: 1. PREDECESSOR, Current vault outpoint. The current Bitcoin output anchors collateral and identifies the state being spent. 2. REQUEST, TEE custody. The TEE custody workflow proposes one exact action and successor state. 3. POLICY, Profile, oracle, signatures. Applicable policy, price evidence, authorization, and transaction shape are checked. 4. BITCOIN SPEND, Script-valid transaction. Bitcoin miners and nodes can include only a transaction that satisfies Bitcoin rules. 5. SUCCESSOR, New outpoint and state. Ducat validators reconstruct debt, collateral, token, and account changes from the confirmed transaction.

1. State transitionWhat exists, what changes, and what results

BEFORE

The policy expects workload measurement ab12 for participant Bob, while an authenticated envelope reports cd34. Required practice uses another measurement.

MECHANISM

First authenticate the signed attestation envelope and certificate chain. Then compare expected code measurement, identity, freshness, and platform evidence before delivering…

AFTER

Matching attestation identifies the measured environment but cannot prove bug absence, honest operators, perfect hardware, or audit completion. Required practice uses a separ…

Text equivalent: Starting from The policy expects workload measurement ab12 for participant Bob, while an authenticated envelope reports cd34. Required practice uses another measurement. The mechanism begins when First authenticate the signed attestation envelope and certificate chain. Then compare expected code measurement, identity, freshness, and platform evidence before delivering sensitive material. The resulting lesson is Matching attestation identifies the measured environment but cannot prove bug absence, honest operators, perfect hardware, or audit completion. Required practice uses a separate server-executed vector.

2. Mechanism pathSelect a stage to inspect its job

STAGE 1 OF 4

Authenticate, then verify the workload

First authenticate the signed attestation envelope and certificate chain. Then compare expected code measurement, identity, freshness, and platform evidence before delivering sensitive material.

Complete path: 1. Authenticate, then verify the workload: First authenticate the signed attestation envelope and certificate chain. Then compare expected code measurement, identity, freshness, and platform evidence before delivering sensitive material. 2. Finalize the DKG share inside: Plaintext participant shares are intended to remain within each enclave during package creation. 3. Seal for later signing: A short-lived sealing key protects the finalized package at rest under the defined custody policy. 4. Sign under measured code: The enclave unseals, validates the bound request, creates the share, and releases only permitted outputs.

3. Rule and failure boundaryWhat accepts the result and where it can stop

ACCEPTED PATH

The worked case executes the named inputs and checks in the displayed order. The enclave unseals, validates the bound request, creates the share, and releases only permitted outputs.

CHANGED CONDITION

A missing, malformed, stale, unauthorized, or inconsistent required input stops at its first named boundary. Attestation identifies measured code and environment. It does not prove bug absence, honest governance, hardware perfection, or operator diversity.

Important distinction: A TEE proves the Guardian software is correct and the operator is independent. Attestation identifies measured code and environment. It does not prove bug absence, honest governance, hardware perfection, or operator diversity.

Text equivalent: The accepted path is enforced by The worked case executes the named inputs and checks in the displayed order. The enclave unseals, validates the bound request, creates the share, and releases only permitted outputs. If the required condition changes, A missing, malformed, stale, unauthorized, or inconsistent required input stops at its first named boundary. Attestation identifies measured code and environment. It does not prove bug absence, honest governance, hardware perfection, or operator diversity.

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Learn the idea

A trusted execution environment, or TEE, is an isolated workload intended to protect code and secrets while they run. An attestation envelope must first pass cryptographic certificate-chain and signature verification. Only authenticated claims can then be compared with workload, identity, platform, and freshness policy. Sealing encrypts a key package so only an approved environment can recover it.

GUIDED EXPLANATION1/4 ideas inspected

Authenticate, then verify the workload

First authenticate the signed attestation envelope and certificate chain. Then compare expected code measurement, identity, freshness, and platform evidence before delivering sensitive material.

The worked example follows the explanation

Inspect every idea above to open it.

Important distinction“A TEE proves the Guardian software is correct and the operator is independent.”

Attestation identifies measured code and environment. It does not prove bug absence, honest governance, hardware perfection, or operator diversity.

FINISH LEARNING FIRST

The questions unlock after every required learning activity

Inspect every guided idea, open the worked example, rebuild its mechanism, and complete the deterministic lesson tool. Your progress is saved automatically.