[PATCH 4/7] pack-protocol.txt: Elaborate on pusher identity

[Dave Borowitz <dborowitz@google.com>]

This is sort of like a standard identity, except that RFC 4880 section
4.11 allows any UTF-8 text in the User ID packet. It is trivial to get
gpg to pass arbitrary text when generating a push cert by setting
user.signingKey to that arbitrary value (assuming it is an actual user
ID associated with that key).

Signed-off-by: Dave Borowitz <dborowitz@google.com>
---
 Documentation/technical/pack-protocol.txt | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/Documentation/technical/pack-protocol.txt b/Documentation/technical/pack-protocol.txt
index 2d8b1a1..de3c72c 100644
--- a/Documentation/technical/pack-protocol.txt
+++ b/Documentation/technical/pack-protocol.txt
@@ -494,7 +494,7 @@ references.
 
   push-cert         = PKT-LINE("push-cert" NUL capability-list LF)
 		      PKT-LINE("certificate version 0.1" LF)
-		      PKT-LINE("pusher" SP ident LF)
+		      PKT-LINE("pusher" SP push-cert-ident LF)
 		      PKT-LINE("pushee" SP url LF)
 		      PKT-LINE("nonce" SP nonce LF)
 		      PKT-LINE(LF)
@@ -502,6 +502,8 @@ references.
 		      *PKT-LINE(gpg-signature-lines LF)
 		      PKT-LINE("push-cert-end" LF)
 
+  push-cert-ident   = 1*(UTF8) SP ["-"] 1*(DIGIT) SP ["-"|"+"] 1*(DIGIT)
+
   packfile          = "PACK" 28*(OCTET)
 ----
 
@@ -540,8 +542,14 @@ Note that (unlike other portions of the protocol), all LFs in the
 Currently, the following header fields are defined:
 
 `pusher` ident::
-	Identify the GPG key in "Human Readable Name <email@address>"
-	format.
+	Identity of the GPG key. This is similar to the identify found
+	elsewhere, such as the author/committer field in commit headers,
+	in that it consists of a name portion, a timestamp, and a
+	timezone offset. However, unlike normal git identities, the name
+	field may be any valid OpenPGP User ID, which is any valid UTF-8
+	string. (By convention this matches the form:
+	"Human Readable Name (optional comment) <email@address>"
+	but this is only a convention.)
 
 `pushee` url::
 	The repository URL (anonymized, if the URL contains
-- 
2.4.3.573.g4eafbef