[cm/signed/] with Ed25519-BLAKE2b.

EdDSA with Edwards25519 is used similarly as in RFC 8032.
But BLAKE2b is used instead of SHA2-512 hash.
Strict ZIP-0215 validation rules should be used while verifying the signature.

=> RFC 8032, EdDSA
=> ZIP-0215

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

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