[cm/signed/] with Ed25519-BLAKE2b.

EdDSA with Edwards25519 is used similarly as in RFC 8032.
But BLAKE2b is used instead of SHA2-512 hash.
=> https://datatracker.ietf.org/doc/html/rfc8032.html RFC 8032, EdDSA

Strict ZIP-0215 validation rules should be used while verifying the signature.
=> https://zips.z.cash/zip-0215 ZIP-0215

PureEdDSA *must* be used when no detached data exists and
"ed25519-blake2b" algorithm identifier is used in signature.

HashEdDSA *must* be used otherwise, using BLAKE2b-512 as a
hash, using "ed25519ph-blake2b" algorithm identifier for
signature.
