Attestation Service overview#

The Solana Attestation Service is an open, permissionless protocol for verifiable on-chain credentials. In Dart, use solana_kit_attestation_service for generated instruction builders, account codecs, PDAs, and a schema-driven attestation data codec.

An issuer registers a Credential with its authorized signers, declares a Schema that names and types its fields, and issues Attestations whose payloads are encoded exactly as the schema declares. Verifiers fetch an attestation, decode its payload with the schema, and check the signer and expiry.

The canonical flow is create-credential, create-schema, create-attestation, then verify:

import 'dart:typed_data';

import 'package:solana_kit/solana_kit.dart';
import 'package:solana_kit_attestation_service/solana_kit_attestation_service.dart';

Future<void> main() async {
  const authority = Address('tbFevHibEdBNFJfZ7xKC8k1th8pt2YPEXTk4sGMxCGa');

  final (credential, _) = await findCredentialPda(
    seeds: const CredentialSeeds(authority: authority, name: 'my-credential'),
  );
  final (schema, _) = await findSchemaPda(
    seeds: SchemaSeeds(credential: credential, name: 'person', version: 1),
  );

  final instruction = getCreateAttestationInstruction(
    programAddress: solanaAttestationServiceProgramAddress,
    payer: authority,
    authority: authority,
    credential: credential,
    schema: schema,
    attestation: authority,
    systemProgram: systemProgramAddress,
    nonce: authority,
    data: Uint8List.fromList([0]),
    expiry: BigInt.zero,
  );
  print(instruction.programAddress);
}

Verification closes the loop: fetch the Attestation and Schema accounts, decode the payload against the schema's declared layout, and check that the attestation's signer is one of the credential's authorized signers and that the expiry has not passed.

import 'dart:convert';
import 'dart:typed_data';

import 'package:solana_kit/solana_kit.dart';
import 'package:solana_kit_attestation_service/solana_kit_attestation_service.dart';

void main() {
  final schema = Schema(
    discriminator: 1,
    credential: const Address('11111111111111111111111111111111'),
    name: Uint8List.fromList(utf8.encode('person')),
    description: Uint8List.fromList(utf8.encode('A person')),
    layout: Uint8List.fromList([
      SchemaDataType.string.index,
      SchemaDataType.u8.index,
    ]),
    fieldNames: Uint8List.fromList([
      4, 0, 0, 0, ...utf8.encode('name'), //
      3, 0, 0, 0, ...utf8.encode('age'),
    ]),
    isPaused: false,
    version: 1,
  );

  // In practice, fetch the attestation with an RPC client, then decode its
  // payload against the schema and check the signer and expiry.
  final payload = serializeAttestationData(schema, {'name': 'Alice', 'age': 42});
  print(deserializeAttestationData(schema, payload));
}

Upstream documentation: https://attest.solana.com/docs