[cm/prv/] with Ed25519-BLAKE2b.
32-byte Ed25519 private key is used, as described in EdDSA RFC.
In many libraries it is called "seed".
=> https://datatracker.ietf.org/doc/html/rfc8032 EdDSA
"ed25519-blake2b" algorithm identifier is used, however actually no
hash is involved in private key storage.