`POST /_matrix/identity/v2/store-invite` returns unspecced `public_key` property

[richvdh]

Sydent returns:

{
    "token": "token",
    "public_key": "sydentPubKeyBase64",
    "public_keys": [
        {
            "public_key": "sydentPubKeyBase64",
            "key_validity_url":  "https://<server>/_matrix/identity/api/v1/pubkey/isvalid"
        },
        {
            "public_key": "ephemeralPublicKeyBase64",
            "key_validity_url": "https://<server>/_matrix/identity/api/v1/pubkey/ephemeral/isvalid",
        }
    ],
    "display_name": "<redacted email>"
}

the top-level public_key property is redundant. It predates public_keys (added in #10, as modified by #13), and has never been specced. It should be removed.

[anoadragon453]

@richvdh This issue talks about /_matrix/identity/v2/store-invite, whereas https://github.com/matrix-org/matrix-spec/issues/495 is talking about /_matrix/identity/api/v1/store-invite (v1 vs. v2). From the description of #495, it sounds like the public_key field should not have existed in either API?

public_key is redundant. ... It should be removed.

This is currently referenced by the following projects:

/_matrix/identity/v2/store-invite

• turt2live/matrix-bot-sdk: https://github.com/turt2live/matrix-bot-sdk/blob/d4612dbb848c8a6af92fae207178e9cf15e9c92e/src/models/IdentityServerModels.ts#L16
• matrix-org/sytest: https://github.com/matrix-org/sytest/blob/3c26f28b44922f6c1248bc37924604f2a077afd7/lib/SyTest/Identity/Server.pm#L485
• matrix-org/synapse (as a fallback, if it exists): https://github.com/matrix-org/synapse/blob/4de271a7fcde6b46611ba2aa9d45cdc6cc7275ab/synapse/handlers/identity.py#L767

/_matrix/identity/api/v1/store-invite

• matrix-org/sytest: https://github.com/matrix-org/sytest/blob/3c26f28b44922f6c1248bc37924604f2a077afd7/lib/SyTest/Identity/Server.pm#L485
• matrix-org/dendrite: https://github.com/matrix-org/dendrite/blob/9b98e5a10282dbf594f46a41baa21191b2d2b8f6/clientapi/threepid/invites.go#L60 (also, the docstring of idServerStoreInviteResponse is a copy/paste error)

Hits in for public_key field did not appear in the following projects, but were checked explicitly: matrix-rust-sdk, matrix-ios-sdk, matrix-android-sdk2, Ruma, famedlysdk (Matrix Dart SDK), ma1sd, Construct and Complement.

[richvdh]

@richvdh This issue talks about /_matrix/identity/v2/store-invite, whereas matrix-org/matrix-spec#495 is talking about /_matrix/identity/api/v1/store-invite (v1 vs. v2).

I don't think matrix-org/matrix-spec#495 is specific to v1 or v2: it predates the existence of v2 (which was added in https://github.com/matrix-org/matrix-spec-proposals/pull/2255), but the same error was carried over to the v2 spec.

Note also that matrix-org/matrix-spec#495 is talking about the format of public_keys rather than the top-level public_key.

From the description of #495, it sounds like the public_key field should not have existed in either API?

I agree that public_key should not have existed in either API. When I opened this issue, I only mentioned v2 because v1 shouldn't exist at all (https://github.com/matrix-org/sydent/issues/338).

---

public_key is redundant. ... It should be removed.

This is currently referenced by the following projects:

/_matrix/identity/v2/store-invite

• turt2live/matrix-bot-sdk: https://github.com/turt2live/matrix-bot-sdk/blob/d4612dbb848c8a6af92fae207178e9cf15e9c92e/src/models/IdentityServerModels.ts#L16

It's referenced in the model, but that doesn't necessarily mean the project is actually using it.

I'm also a bit surprised that a bot SDK needs to reference this. Per the ASCII art at https://spec.matrix.org/v1.6/client-server-api/#server-behaviour-7, it should be up to the homeserver to make this request.

• matrix-org/sytest: https://github.com/matrix-org/sytest/blob/3c26f28b44922f6c1248bc37924604f2a077afd7/lib/SyTest/Identity/Server.pm#L485

Yup, looks like that line needs removing too, to make sytest return spec-compliant responses.

• matrix-org/synapse (as a fallback, if it exists): https://github.com/matrix-org/synapse/blob/4de271a7fcde6b46611ba2aa9d45cdc6cc7275ab/synapse/handlers/identity.py#L767

See https://github.com/matrix-org/synapse/issues/6036. We should remove it.

/_matrix/identity/api/v1/store-invite

• matrix-org/sytest: https://github.com/matrix-org/sytest/blob/3c26f28b44922f6c1248bc37924604f2a077afd7/lib/SyTest/Identity/Server.pm#L485

As above, needs a fix.

• matrix-org/dendrite: https://github.com/matrix-org/dendrite/blob/9b98e5a10282dbf594f46a41baa21191b2d2b8f6/clientapi/threepid/invites.go#L60 (also, the docstring of idServerStoreInviteResponse is a copy/paste error)

Again, hard to tell if this means it's actually used. I'd hope that fixing sytest would confirm one way or the other.

Thanks for doing all this research!