crypto: Move device_keys to DecryptedOlmV1Event as per MSC4147

[andybalaam]

Part of #3542

Fixes a mistake I made in #3556 - I included device_keys in the content and it should be outside as per MSC4147

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.26%. Comparing base (9aa2774) to head (25ed92f).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3633      +/-   ##
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- Coverage   84.26%   84.26%   -0.01%     
==========================================
  Files         259      259              
  Lines       26596    26595       -1     
==========================================
- Hits        22411    22410       -1     
  Misses       4185     4185              

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[poljar]

Looks good, but now that #3517 has been merged we can add a test confirming that we put things in the right place.

[andybalaam]

Looks good, but now that #3517 has been merged we can add a test confirming that we put things in the right place.

Can I have a hint on how to write a test? I've spent the day trying to call matrix_sdk_crypto::olm::session::Session::encrypt or matrix_sdk_crypto::identities::device::ReadOnlyDevice::maybe_encrypt_room_key or similar and then feed the result into matrix_sdk_crypto::olm::account::Account::decrypt_to_device_eventto check that the device keys come through, but I haven't managed to find the right incantation and I can't find any tests that directly call these things.

Is there an example I can follow? Thanks

[poljar]

Looks good, but now that #3517 has been merged we can add a test confirming that we put things in the right place.

Can I have a hint on how to write a test? I've spent the day trying to call matrix_sdk_crypto::olm::session::Session::encrypt or matrix_sdk_crypto::identities::device::ReadOnlyDevice::maybe_encrypt_room_key or similar and then feed the result into matrix_sdk_crypto::olm::account::Account::decrypt_to_device_eventto check that the device keys come through, but I haven't managed to find the right incantation and I can't find any tests that directly call these things.

Is there an example I can follow? Thanks

#3517 added a test which uses the weaker serde_json::Value type to check this:

matrix-rust-sdk/crates/matrix-sdk-crypto/src/olm/session.rs

Lines 351 to 353 in 2507a45

	// Also ensure that the encrypted payload has the device keys.
	let plaintext: Value = serde_json::from_str(&bob_session_result.plaintext).unwrap();
	assert_eq!(plaintext["device_keys"]["user_id"].as_str(), Some("@alice:localhost"));

You could modify this test to also check using our stronger type you modified.

[andybalaam]

You could modify this test to also check using our stronger type you modified.

Thank you, done in 46b4d00

[andybalaam]

Out of interest, do you know why Session::encrypt uses json! instead of constructing and serializing a DecryptedOlmV1Event?

[poljar]

Out of interest, do you know why Session::encrypt uses json! instead of constructing and serializing a DecryptedOlmV1Event?

Nowadays probably just for historic reasons, we didn't use to have the DecryptedOlmV1Event type. But I'm not completely sure that we can just exchange the types, the C in DecryptedOlmV1Event has more trait bounds, if it's possible it certainly isn't easy.