ed25519, rsa ref done

_ref/KEY_GUIDE.adoc

@@ -13,6 +13,7 @@ Last updated {localdatetime}
 :idprefix:
 :toclevels: 7
 :source-highlighter: rouge
+:docinfo: shared
 
 == Purpose
 This document attempts to present a much more detailed, thorough, and easily-understood form of the key formats used by OpenSSH. The extent of those formats' canonical documentation is https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key[the OpenSSH source tree's `PROTOCOL.key`^], which is a little lacking.
@@ -35,14 +36,29 @@ A:: The key type (e.g. `ssh-rsa`, `ssh-ed25519`, etc.)
 B:: The public key itself, Base64footnote:[https://datatracker.ietf.org/doc/html/rfc4648]-encoded
 C:: The key's comment
 
-The structures specified in the breakdowns later in this document describe the _decoded_ version of *B* *_only_*.
+The structures specified in the breakdowns later in this document describe the _decoded_ version of *B* *_only_*. They are specific to each keytype and format version starting with item `2.0`.
 
 
 === New "v1" Format
 ==== Private Keys
+
+Private key structures have been retooled in the "v1" format. In recent OpenSSH versions, all new keys use the v1 format. They no longer are in straight PEM-compatible format.
+
+Refer to https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key[`PROTOCOL.key`^] for a (very) general description, or each key's specific breakdown for more detailed information.
+
+The v1 format offers several benefits over the legacy format, including:
+
+* customizable key derivation and encryption ciphers for encrypted private keys
+* embedded comments
+* embedded public key (no need to derive from the private key)
+* "checksumming" to confirm proper decryption for encrypted keys
+
 ==== Public Keys
 
+All public keys in v1 continue to use the same packed binary format as <<public_keys, the legacy format>>.
+
 == Keytype-Specific Breakdowns
+
 include::rsa/main.adoc[]
 
-=== ED25519
+include::ed25519/main.adoc[]