cannot multiply &&EdwardsBasepointTable by &Scalar

[Kofituo]

Hi there, I'm facing this issue when compiling my Substrate program:

error[E0369]: cannot multiply `&&EdwardsBasepointTable` by `&Scalar`
   --> /Users/kofiotuo/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/snow-0.9.0/src/resolvers/default.rs:132:47
    |
132 |         let point = (&ED25519_BASEPOINT_TABLE * &self.privkey).to_montgomery();
    |                      ------------------------ ^ ------------- &Scalar
    |                      |
    |                      &&EdwardsBasepointTable
    |
help: `*` can be used on `&EdwardsBasepointTable` if you dereference the left-hand side
    |
132 |         let point = (*&ED25519_BASEPOINT_TABLE * &self.privkey).to_montgomery();
    |                      +

For more information about this error, try `rustc --explain E0369`.
error: could not compile `snow` due to previous error

[evilrobot-01]

Also just encountered this, seems the latest version of curve25519-dalek v4.0.0-rc.0 released 18 hours ago is causing the issue.

Manually downgrading to the previous version resolved it for me:

cargo update -p [email protected] --precise 4.0.0-pre.5

[tarcieri]

In the rc.0 release, you'll probably want to switch to the new mul_base method:

let point = EdwardsPoint::mul_base(&self.privkey).to_montgomery();

This abstracts over various fixed-base scalar multiplication implementations based on what optimizations are available, including using the basepoint tables.

[tarcieri]

Here's a PR which adds a first-class API for this: dalek-cryptography/curve25519-dalek#503

[thomaseizinger]

Likely, the culprit here is that snow depends on curve25519-dalek with the implicit caret (^) operator which allows cargo to look for semver-compatible versions:

snow/Cargo.toml

Line 48 in dd50e62

curve25519-dalek = { version = "4.0.0-pre.2", optional = true }

Pre-releases are compared lexically, an rc happens to have a higher precedence than pre.

Would it possible to get a hotfix release for snow that pins the curve25519-dalek version like this?

curve25519-dalek = { version = "=4.0.0-pre.2", optional = true }

[thomaseizinger]

Submitted a PR here: #147

[mcginty]

Published a patch fix (v0.9.1) on to a new 0.9 branch https://github.com/mcginty/snow/tree/0.9, as the main branch has API-breaking changes. Should be live on crates now!