Optimism Docs

AttestationStation v0

Deprecated

This contract is not actively being supported, we recommend using AttestationStation v1.

These attestations have these attributes:

  • Creator, the address that wrote the attestation.
  • Key, a 32 byte value that identifies the attestation. This value can be a short ASCII string, it can be the hash value of a longer (>32 characters) string, or it can be anything else. It is possible for different creators to use the same key for different purposes.
  • Value, a string of bytes that can be interpreted as ASCII, a number, etc.

The interpretation of the attestation is up to the creator, and is not necessarily stored onchain.

Here is the tutorial (opens new window)

# Searches

To look for an attestation you have to know the creator, the address it is about, and the key. If you want to search for information (for example, “all attestations about address X” or “all attestations created by address Y for key Z”), you need to search offchain.

To optimize for performance, there are several APIs that you can use to search attestations:

Alternatively, you can look at AttestationCreated events on the blockchain. This way there is no centralized authority to trust.

# Smart contracts / technical specifications

The legacy AttestationStation contract is located in the Optimism monorepo (opens new window). It is deployed at address 0xEE36eaaD94d1Cc1d0eccaDb55C38bFfB6Be06C77, both on Optimism Mainnet (opens new window) and Optimism Goerli (opens new window). The following is the breakdown of this smart contract.

# State

# attestations

The following is the nested mapping that stores all the attestations made.

mapping(address => mapping(address => mapping(bytes32 => bytes))) public attestations;
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# AttestationData

The following is a struct that represents a properly formatted attestation.

struct AttestationData {
    address about;
    bytes32 key;
    bytes val;
}
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# Event: AttestationCreated

This event is emitted when an attestation is successfully made.

event AttestationCreated(
    address indexed creator,
    address indexed about,
    bytes32 indexed key,
    bytes val
);
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# Functions

# attest(address _about, bytes32 _key, bytes memory _val)

Records attestations to the AttestationStation's state and emits an AttestationCreated event with the address of the message sender, address the attestation is about, the bytes32 key, and bytes value.

function attest(address _about, bytes32 _key, bytes memory _val) public
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Allows anyone to create an attestation.

Name Type Description
_about address Address that the attestation is about.
_key bytes32 A key used to namespace the attestation.
_val bytes An arbitrary value stored as part of the attestation.

# attest(AttestationData[] memory _attestations)

function attest(AttestationData[] memory _attestations) public
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Allows anyone to create attestations.

Parameters:

Name Type Description
_attestations AttestationData[] An array of attestation data.

# Attestation hacks

Applications