PKCS#8 PEM, not this host's own base64. The mesh delivers a PEM certificate
beside it and every TLS server there is reads PEM: nginx's ssl_certificate_key,
Go's LoadX509KeyPair, openssl s_server. Stored the other way the file was
intact, present, correctly permissioned, and unusable — the machine failed at
the moment something connected, which the lab found by connecting.
A key in the old encoding is refused by name rather than called corrupt: it is
replaced by enrolling again, and that is a different remedy from a damaged
file.
A fourth key, reported at enrolment like the others. The reasoning is the
one this file's neighbours already give twice: a key used for two
purposes is one rotation away from breaking the other.
The private half never leaves the machine. The mesh is told the public
half and signs a certificate binding it to this node's name inside the
mesh — so there is nothing to seal, and a copy of what the mesh holds
certifies nothing it did not already certify.
It does not make one on demand, for the same reason the sealing key does
not: a key the mesh has never certified is a key nothing will trust, so a
node that quietly generated one would serve a certificate for a key it no
longer has and fail in a way that names neither.
jschoubben