The ACME store holds the account key and every leaf private key the edge has
been issued. It was JSON at mode 0600 on a node, which protects it from another
UID on that node and from nothing else. It is now sealed under a key fetched
from KMS at startup and held only in memory, so the file on the node is inert.
pkg/kms speaks the same luxfi/kms contract the gateway's routes loader does, so
the estate has one KMS conversation rather than two.
zeekay
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