Struct RCompute 

pub(crate) struct RCompute<CtxDigest> {
    key: VerifyingKey,
    signature: InternalSignature,
    h: CtxDigest,
}

Helper for verification. Computes the expected R component of the signature. The caller compares this to the real R component. This computes H(R || A || M) where H is the 512-bit hash function given by CtxDigest (this is SHA-512 in spec-compliant Ed25519).

For pre-hashed variants a h with the context already included can be provided. Note that this returns the compressed form of R and the caller does a byte comparison. This means that all our verification functions do not accept non-canonically encoded R values. See the validation criteria blog post for more details: https://hdevalence.ca/blog/2020-10-04-its-25519am

Fields

key: VerifyingKey

signature: InternalSignature

h: CtxDigest

Implementations

impl<CtxDigest> RCompute<CtxDigest>

where CtxDigest: Digest<OutputSize = U64>,

pub(crate) fn compute( key: &VerifyingKey, signature: InternalSignature, prehash_ctx: Option<&[u8]>, message: &[&[u8]], ) -> CompressedEdwardsY

If prehash_ctx.is_some(), this does the prehashed variant of the computation using its contents.

pub(crate) fn new( key: &VerifyingKey, signature: InternalSignature, prehash_ctx: Option<&[u8]>, ) -> Self

pub(crate) fn update(&mut self, m: &[u8])

pub(crate) fn finish(self) -> CompressedEdwardsY