38 lines
1.5 KiB
Markdown
38 lines
1.5 KiB
Markdown
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# Guardian Key Usage
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## Objective
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* Describe how guardian keys are used and how message confusion is avoided.
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## Background
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Message confusion could occur when a Guardian signs a message and an attacker replays that message elsewhere where it is interpreted as a different message type, which could lead to unintended behavior.
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## Overview
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The Guardian Key is used to:
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1. Sign gossip messages
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1. heartbeat
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2. governor config and governor status
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3. observation request
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2. Sign Observations
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1. Version 1 VAAs
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2. Version 2 VAAs, i.e. Batch VAAs.
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## Detailed Design
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Signing of gossip messages:
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1. Prepend the message type prefix to the payload
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2. Compute Keccak256Hash of the payload.
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3. Compute ethcrypto.Sign()
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Signing of Observations:
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* v1 VAA: `double-Keccak256(observation)`.
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* v2 (batchVAA): `double-Keccak256(version | Keccak256(hash1 | hash2 | ... | hash_n))`, where `|` stands for concatenation.
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Rationale
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* Gossip messages cannot be confused with other gossip messages because the message type prefix is prepended.
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* Gossip messages cannot be confused with observations because observations utilize a double-Keccak256 and the payload is enforced to be `>=34` bytes.
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* v2 VAAs cannot be confused as v1 VAAs because their payload when parsed as a v1 VAA is only 33 bytes, which does not constitute a valid observation.
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* v1 VAAs cannot be confused as v2 VAAs because observations are longer than 33 bytes and hence do not constitute a valid v2 VAA body.
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