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RetroRelay
Credits

Open-source components

The third-party libraries RetroRelay is built on, with thanks.

RetroRelay stands on the shoulders of the open-source community. The web app, server, and pairing flow are all built on top of freely licensed libraries published by Microsoft, Google, Stripe, and many individual maintainers. We are grateful for their work.

Every component listed below is distributed under a permissive open-source licence (MIT, Apache 2.0, BSD-3-Clause, or the SIL Open Font License 1.1 for the typefaces) and is used in accordance with the terms of that licence. License notices are reproduced here for the attribution those licences require.

Server

Web app

Fonts, icons & browser libraries

  • Inter · SIL Open Font License 1.1
    © The Inter Project Authors
  • Nunito · SIL Open Font License 1.1
    © The Nunito Project Authors
  • JetBrains Mono · SIL Open Font License 1.1
    © The JetBrains Mono Project Authors
  • Bootstrap Icons · MIT License
    © 2019–2024 The Bootstrap Authors
  • jsQR · Apache License 2.0
    © Cosmo Wolfe. Decodes authenticator QR codes locally in your browser.
  • Firebase JS SDK · Apache License 2.0
    © Google LLC. Powers sign-in and live dashboard data. Version 10.9.0, served from our own site rather than Google’s CDN; our copy carries a notice of the one change we make to it.

Companion app (retro phones)

The J2ME app that runs on paired retro phones uses only the standard MIDP 2.0 / CLDC 1.0 APIs provided by the phone manufacturer's Java runtime: no third-party libraries are bundled into the JAR.

The Java is written by Adapanos Ltd, with two cores ported by hand from well-known reference implementations, with thanks: the Poly1305 authenticator follows poly1305-donna (Andrew Moon, public domain), and the DEFLATE decompressor follows Mark Adler's puff.c and Jørgen Ibsen's tinf (zlib licence). Everything else, including the ChaCha20 cipher and TOTP, is hand-written against the published specifications.

Licence summary

All third-party components use one of four permissive licences:

  • MIT Licence. Used by most Microsoft .NET packages, SkiaSharp, Otp.NET, Newtonsoft.Json, Bootstrap Icons, and others.
  • Apache Licence 2.0. Used by Firebase Admin, Google Cloud Firestore, Stripe.net, the gRPC libraries, ZXing.Net, jsQR, and the Firebase browser SDK.
  • BSD 3-Clause. Used by Google API Gax, Google.Api.CommonProtos, and Google Protocol Buffers.
  • SIL Open Font License 1.1. Used by the Inter, Nunito, and JetBrains Mono typefaces.

The two reference-code ports inside the companion app (above) are public domain and zlib-licensed respectively. Full licence text for each component is available from the upstream project linked next to each package above.

Bill of materials

A machine-readable Software Bill of Materials (SBOM, CycloneDX format) covering all third-party components is maintained alongside each release and is available on request for security or compliance purposes. Contact contact@retrorelay.app.

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