two_level_qr 0.2.0

TwoLevelQR - A Dart SDK that implements a keyed two-level QR mode that hides a secret message, optionally encrypted (AES-SIV, ChaCha20-Poly1305), during encoding of a QR.

Change Log

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

0.1.0 - 2026-09-25

Initial release

0.1.1 - 2026-09-25

Adding files required for publishing to pub.dev

0.2.0 - 2026-10-01

Added

• Encrypted hidden messages: TwoLevelQr.encodeWithEncryptedHiddenMessage and TwoLevelQr.decodeWithEncryptedHiddenMessage, with separate positionKey and encryptionPassphrase. Decoding never falls back to plaintext; failures throw HiddenMessageCryptoException subclasses.
• Pluggable HiddenMessageCipher contract. A one-byte scheme ID in the hidden channel tells the receiver which cipher was used.
• Built-in ciphers: AesSivCipher (AES-SIV-CMAC-512, default, all platforms) and ChaCha20Poly1305Cipher (native platforms), using pointycastle.
• PassphraseKdf (PBKDF2-HMAC-SHA256) with a configurable iteration count (default 1000; kdfIterations on the facade, iterations on the ciphers).
• TwoLevelQr.hiddenMessageCapacity for plaintext and encrypted modes.
• EncodeHiddenQr.executeWithPayload, DecodeHiddenQr.extractChannel, EncodeResult.hiddenCipherSchemeId, and HiddenMessageCapacityException.overheadBytes.
• example/main.dart.
• Test vectors: RFC 5297, Wycheproof AES-SIV-CMAC, RFC 8439, RFC 7914.

Fixed

• The package now compiles for the web. The keyed position scheduler emulates its 64-bit arithmetic, so schedules are bit-identical on every platform and codes created with 0.1.x still decode.
• Automatic version bumping only retries on capacity overflow instead of on any ArgumentError.

Changed

• Minimum Dart SDK is now 3.2.0 (required by pointycastle 4).
• Plaintext hidden-message output is unchanged byte for byte (covered by a golden test).