Advisories for Cargo/Libsecp256k1 package

An issue was discovered in the libsecp256k1 crate before 0.5.0 for Rust. It can verify an invalid signature because it allows the R or S parameter to be larger than the curve order, aka an overflow.

Versions of libsecp256k1 prior to 0.3.1 did not execute Scalar::check_overflow in constant time. This allows an attacker to potentially leak information via a timing attack. The flaw was corrected by modifying Scalar::check_overflow to execute in constant time.