solana_kit_offchain_messages 0.5.1

Off-chain message signing for the Solana Kit Dart SDK.

solana_kit_offchain_messages

Create, compile, sign, and verify Solana offchain messages. Offchain messages let wallets sign structured data that is never submitted to the network, following the off-chain message signing specification.

Installation

Install the package directly:

dependencies:
  "solana_kit_offchain_messages": ^0.5.1

If your app uses several Solana Kit packages together, you can also depend on the umbrella package instead:

dart pub add solana_kit

Inside this monorepo, Dart workspace resolution uses the local package automatically.

Documentation

• Package page: https://pub.dev/packages/solana_kit_offchain_messages
• API reference: https://pub.dev/documentation/solana_kit_offchain_messages/latest/
• Workspace docs: https://openbudgetfun.github.io/solana_kit/
• Package catalog entry: https://openbudgetfun.github.io/solana_kit/reference/package-catalog#solana_kit_offchain_messages
• Source code: https://github.com/openbudgetfun/solana_kit/tree/main/packages/solana_kit_offchain_messages

For architecture notes, getting-started guides, and cross-package examples, start with the workspace docs site and then drill down into the package README and API reference.

Usage

Creating offchain messages

Version 0 messages include an application domain, formatted content, and required signatories.

import 'package:solana_kit_addresses/solana_kit_addresses.dart';
import 'package:solana_kit_offchain_messages/solana_kit_offchain_messages.dart';

void main() {
  const signerA = Address('11111111111111111111111111111111');
  const signerB = Address('TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA');

  final message = OffchainMessageV0(
    applicationDomain: offchainMessageApplicationDomain(
      '11111111111111111111111111111111',
    ),
    content: const OffchainMessageContent(
      format: OffchainMessageContentFormat.restrictedAscii1232BytesMax,
      text: 'Hello from Solana Kit',
    ),
    requiredSignatories: const [
      OffchainMessageSignatory(address: signerA),
      OffchainMessageSignatory(address: signerB),
    ],
  );

  final envelope = compileOffchainMessageEnvelope(message);

  print('Envelope byte length: ${envelope.content.length}');
  print('Required signatures: ${envelope.signatures.length}');
}

Version 1 messages have simpler UTF-8 text content with no application domain.

import 'package:solana_kit_addresses/solana_kit_addresses.dart';
import 'package:solana_kit_offchain_messages/solana_kit_offchain_messages.dart';

void main() {
  final message = OffchainMessageV1(
    content: 'I agree to the terms and conditions of Acme Corp.',
    requiredSignatories: const [
      OffchainMessageSignatory(address: Address('11111111111111111111111111111111')),
    ],
  );

  final envelope = compileOffchainMessageEnvelope(message);
  print('Envelope byte length: ${envelope.content.length}');
}

Signing and verifying

signOffchainMessageEnvelope fills the envelope's signature map with key pairs, and verifyOffchainMessageEnvelope checks that all required signatories have valid signatures.

import 'package:solana_kit_addresses/solana_kit_addresses.dart';
import 'package:solana_kit_keys/solana_kit_keys.dart';
import 'package:solana_kit_offchain_messages/solana_kit_offchain_messages.dart';

void main() {
  final keyPair = generateKeyPair();

  final message = OffchainMessageV0(
    applicationDomain: offchainMessageApplicationDomain(
      '11111111111111111111111111111111',
    ),
    content: const OffchainMessageContent(
      format: OffchainMessageContentFormat.restrictedAscii1232BytesMax,
      text: 'Sign to verify your identity.',
    ),
    requiredSignatories: const [
      OffchainMessageSignatory(address: Address('11111111111111111111111111111111')),
    ],
  );
  final envelope = compileOffchainMessageEnvelope(message);

  final signed = signOffchainMessageEnvelope([keyPair], envelope);
  verifyOffchainMessageEnvelope(signed);

  print('Envelope verified');
}

Codecs

Each message version has encoder, decoder, and codec factories, plus a version-dispatching codec and an envelope codec.

import 'package:solana_kit_addresses/solana_kit_addresses.dart';
import 'package:solana_kit_offchain_messages/solana_kit_offchain_messages.dart';

void main() {
  final v0Codec = getOffchainMessageV0Codec();
  final v1Codec = getOffchainMessageV1Codec();
  final codec = getOffchainMessageCodec();
  final envelopeCodec = getOffchainMessageEnvelopeCodec();

  final v0 = OffchainMessageV0(
    applicationDomain: offchainMessageApplicationDomain(
      '11111111111111111111111111111111',
    ),
    content: const OffchainMessageContent(
      format: OffchainMessageContentFormat.restrictedAscii1232BytesMax,
      text: 'Hello',
    ),
    requiredSignatories: const [
      OffchainMessageSignatory(address: Address('11111111111111111111111111111111')),
    ],
  );

  print(v0Codec.encode(v0).length);
  print(
    v1Codec
        .encode(
          OffchainMessageV1(
            content: 'Hello',
            requiredSignatories: const [
              OffchainMessageSignatory(address: Address('11111111111111111111111111111111')),
            ],
          ),
        )
        .length,
  );
  print(codec.encode(v0).length);
  print(envelopeCodec.encode(compileOffchainMessageEnvelope(v0)).length);
}

Key APIs

• OffchainMessageV0 / OffchainMessageV1: the two message versions.
• OffchainMessageContent, OffchainMessageSignatory, offchainMessageApplicationDomain.
• compileOffchainMessageEnvelope, signOffchainMessage, verifyOffchainMessage.
• Codec factories: getOffchainMessageV0Codec, getOffchainMessageV1Codec, getOffchainMessageCodec, getOffchainMessageEnvelopeCodec.

Example

Use example/main.dart as a runnable starting point for solana_kit_offchain_messages.

• Import path: package:solana_kit_offchain_messages/solana_kit_offchain_messages.dart
• This section is centrally maintained with mdt to keep package guidance aligned.
• After updating shared docs templates, run docs:update from the repo root.

Maintenance

• Validate docs in CI and locally with docs:check.
• Keep examples focused on one workflow and reference package README sections for deeper API details.