Ed448 keys are indicated as having a 456-bit "security level"
It's not clear why a curve448 key might claim to have 456 bits of "security":
0 dkg@alice:~$ certtool --generate-privkey --key-type ed448 Generating a 256 bit EdDSA (Ed448) private key ... Public Key Info: Public Key Algorithm: EdDSA (Ed448) Key Security Level: Ultra (456 bits) curve: Ed448 …
I think this should be 448 bits. (i know that "security levels" in the Ultra range are basically indistinguishable in their overwhelming strength, but this is still a bit of an odd mismatch)