A simple transcript trait definition, along with viable options

4 releases

Uses new Rust 2021

0.2.0 Nov 5, 2022
0.1.3 Jul 12, 2022
0.1.2 Jun 28, 2022
0.1.1 Jun 27, 2022

#303 in Cryptography

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Used in 5 crates (4 directly)

MIT license

101 lines

Flexible Transcript

Flexible Transcript is a crate offering:

  • Transcript, a trait offering functions transcripts should implement.
  • DigestTranscript, a competent transcript format instantiated against a provided hash function.
  • MerlinTranscript, a wrapper of merlin into the trait (available via the merlin feature).
  • RecommendedTranscript, a transcript recommended for usage in applications. Currently, this is DigestTranscript<Blake2b512> (available via the recommended feature).

The trait was created while working on an IETF draft which defined an incredibly simple transcript format. Extensions of the protocol would quickly require a more competent format, yet implementing the one specified was mandatory to meet the specification. Accordingly, the library implementing the draft defined an IetfTranscript, dropping labels and not allowing successive challenges, yet thanks to the trait, allowed protocols building on top to provide their own transcript format as needed.

DigestTranscript takes in any hash function implementing Digest, offering a secure transcript format around it. All items are prefixed by a flag, denoting their type, and their length.

MerlinTranscript was used to justify the API, and if any issues existed with DigestTranscript, enable a fallback. It was also meant as a way to be compatible with existing Rust projects using merlin.


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