rust-elements

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It appears that the bincode value fix resulted in a different serialization format compared to before the regression (v0.16).

With current master (fe3e9469618a479de02f8ececf92f9d456fc4c38), the following code:

let commitment = PedersenCommitment::from_slice(&Vec::from_hex("09b88680778d3d5530785ff12bb62e6ac98c7be5a8b9b0ea392e166bf61ea77ee4").unwrap()).unwrap();
let value = Value::Confidential(commitment);

println!("BE bytes: {}", bincode::serialize(&value).unwrap().to_hex());
println!("LE bytes: {}", bincode::DefaultOptions::default().with_little_endian()
    .serialize(&value).unwrap().to_hex());

Results in the following serialization:

BE bytes: 020000000000000002210000000000000009b88680778d3d5530785ff12bb62e6ac98c7be5a8b9b0ea392e166bf61ea77ee4
LE bytes: 02022109b88680778d3d5530785ff12bb62e6ac98c7be5a8b9b0ea392e166bf61ea77ee4

While with v0.16, the following code:

let value = Value::from_commitment(&Vec::from_hex("09b88680778d3d5530785ff12bb62e6ac98c7be5a8b9b0ea392e166bf61ea77ee4").unwrap()).unwrap();

println!("BE bytes: {}", bincode::serialize(&value).unwrap().to_hex());
println!("LE bytes: {}", bincode::DefaultOptions::default().with_little_endian()
    .serialize(&value).unwrap().to_hex());

Results in the following serialization:

BE bytes: 020000000000000009b88680778d3d5530785ff12bb62e6ac98c7be5a8b9b0ea392e166bf61ea77ee4
LE bytes: 0209b88680778d3d5530785ff12bb62e6ac98c7be5a8b9b0ea392e166bf61ea77ee4

(The links in the first line don't work.)

Seems like https://github.com/ElementsProject/rust-elements/pull/77 introduced this. We definitely could use more tests where all serializations are tested for regressions.

(The links in the first line don't work.)

Oops, sorry, fixed them now.

To give some more context, this incompatibility resulted in electrs being unable to read db entries that were created with rust-elements v0.16 using the current master. Working around this issue required deleting the old database and running a re-index.

It's the danger of having all our releases be breaking. 0.15-0.16 is breaking, so both rust-elements, electrs and espora should have had regression tests for data formats..