The test suite should include a set of well-known CHK, SDMF, and MDMF capabilities for use as compatibility test vectors

[exarkun]

The test suite has a lot of capabilities in it. However, these are mostly hard-coded without associated inputs so they cannot be reproduced or they are computed from intermediate values rather than original inputs (for example, one is computed from a synthetic URI extension block hash - the original URI extension block is nowhere to be seen).

Thus, these values are not useful for verifying that Tahoe-LAFS continues to produce the same capabilities given the same inputs over time (ie, from release to release). Also, they are not useful for verifying interoperability of another implementation of the cryptography protocol.

Tahoe-LAFS should include a set of capability strings as test vectors, alongside the inputs necessary to compute those capabilities. These should be in a format where it's easy to add more in the future (and so also a format that's versioned so we can talk about specific revisions of the test vectors easily) and a format that can easily be loaded from another implementation.

[exarkun]

​https://github.com/tahoe-lafs/tahoe-lafs/pull/1243

[GitHub <noreply@…>]

In 8735845/trunk:

Merge pull request #1243 from exarkun/3961.test-vectors

Add capability test vectors

Fixes: ticket:3961