V2 certificate format (#1216)

Co-authored-by: Nate Brown <nbrown.us@gmail.com>
Co-authored-by: Jack Doan <jackdoan@rivian.com>
Co-authored-by: brad-defined <77982333+brad-defined@users.noreply.github.com>
Co-authored-by: Jack Doan <me@jackdoan.com>

cert/cert_v2.asn1

@@ -0,0 +1,37 @@
+Nebula DEFINITIONS AUTOMATIC TAGS ::= BEGIN
+
+Name ::= UTF8String (SIZE (1..253))
+Time ::= INTEGER (0..18446744073709551615) -- Seconds since unix epoch, uint64 maximum
+Network ::= OCTET STRING (SIZE (5,17)) -- IP addresses are 4 or 16 bytes + 1 byte for the prefix length
+Curve ::= ENUMERATED {
+    curve25519 (0),
+    p256 (1)
+}
+
+-- The maximum size of a certificate must not exceed 65536 bytes
+Certificate ::= SEQUENCE {
+    details OCTET STRING,
+    curve Curve DEFAULT curve25519,
+    publicKey OCTET STRING,
+    -- signature(details + curve + publicKey) using the appropriate method for curve
+    signature OCTET STRING
+}
+
+Details ::= SEQUENCE {
+    name Name,
+
+    -- At least 1 ipv4 or ipv6 address must be present if isCA is false
+    networks SEQUENCE OF Network OPTIONAL,
+    unsafeNetworks SEQUENCE OF Network OPTIONAL,
+    groups SEQUENCE OF Name OPTIONAL,
+    isCA BOOLEAN DEFAULT false,
+    notBefore Time,
+    notAfter Time,
+
+    -- issuer is only required if isCA is false, if isCA is true then it must not be present
+    issuer OCTET STRING OPTIONAL,
+    ...
+    -- New fields can be added below here
+}
+
+END