Merge commit 'dkg/master'

12 files changed, 387 insertions, 26 deletions

diff --git a/changelog b/changelog
index b9a9e21..4264fa4 120000
--- a/changelog
+++ b/changelog
@@ -1 +1 @@
-website/changelog
\ No newline at end of file
+packaging/debian/changelog
\ No newline at end of file
diff --git a/packaging/debian/changelog b/packaging/debian/changelog
index 62f021e..39e4b33 100644
--- a/packaging/debian/changelog
+++ b/packaging/debian/changelog
@@ -1,3 +1,21 @@
+monkeysphere (0.22~pre-1) UNRELEASED; urgency=low
+
+  * New upstream release:
+  [ Jameson Rollins ]
+
+    - added info log output when a new key is added to known_hosts file.
+    - added some useful output to the ssh-proxycommand for "marginal"
+      cases where keys are found for host but do not have full validity.
+    - force ssh-keygen to read from stdin to get ssh key fingerprint.
+
+  [ Daniel Kahn Gillmor ]
+
+    - automatically output two copies of the host's public key: one
+    standard ssh public key file, and the other a minimal OpenPGP key with
+    just the latest valid self-sig.
+
+ -- Jameson Graef Rollins <jrollins@finestructure.net>  Mon, 17 Nov 2008 18:15:43 -0500
+
 monkeysphere (0.21-2) unstable; urgency=low
 
   * actually rmdir /var/lib/monkeysphere-* during prerm if possible.
diff --git a/src/common b/src/common
index 297e7f3..51b0470 100644
--- a/src/common
+++ b/src/common
@@ -639,7 +639,7 @@ process_user_id() {
 		;;
 	    'uid') # user ids
 		if [ "$lastKey" != pub ] ; then
-		    log verbose " - got a user ID after a sub key?!  user IDs should only follow primary keys!"
+		    log verbose " ! got a user ID after a sub key?!  user IDs should only follow primary keys!"
 		    continue
 		fi
 		# if an acceptable user ID was already found, skip
@@ -652,6 +652,8 @@ process_user_id() {
 		    if [ "$validity" = 'u' -o "$validity" = 'f' ] ; then
 			# mark user ID acceptable
 			uidOK=true
+		    else
+			log debug "  - unacceptable user ID validity ($validity)."
 		    fi
 		else
 		    continue
@@ -693,10 +695,12 @@ process_user_id() {
 		
 		# if sub key validity is not ok, skip
 		if [ "$validity" != 'u' -a "$validity" != 'f' ] ; then
+		    log debug "  - unacceptable sub key validity ($validity)."
 		    continue
 		fi
 		# if sub key capability is not ok, skip
 		if ! check_capability "$usage" $requiredCapability ; then
+		    log debug "  - unacceptable sub key capability ($usage)."
 		    continue
 		fi
 
@@ -742,6 +746,7 @@ process_user_id() {
 process_host_known_hosts() {
     local host
     local userID
+    local noKey=
     local nKeys
     local nKeysOK
     local ok
@@ -768,8 +773,9 @@ process_host_known_hosts() {
             continue
         fi
 
-	# remove the old host key line, and note if removed
-	remove_line "$KNOWN_HOSTS" "$sshKey"
+	# remove any old host key line, and note if removed nothing is
+	# removed
+	remove_line "$KNOWN_HOSTS" "$sshKey" || noKey=true
 
 	# if key OK, add new host line
 	if [ "$ok" -eq '0' ] ; then
@@ -788,6 +794,11 @@ process_host_known_hosts() {
 	    else
 		ssh2known_hosts "$host" "$sshKey" >> "$KNOWN_HOSTS"
 	    fi
+
+	    # log if this is a new key to the known_hosts file
+	    if [ "$noKey" ] ; then
+		log info "* new key for $host added to known_hosts file."
+	    fi
 	fi
     done
 
diff --git a/src/monkeysphere-server b/src/monkeysphere-server
index 5edaa4f..a1844ee 100755
--- a/src/monkeysphere-server
+++ b/src/monkeysphere-server
@@ -132,13 +132,13 @@ show_server_key() {
     fingerprint=$(fingerprint_server_key)
     gpg_authentication "--fingerprint --list-key --list-options show-unusable-uids $fingerprint"
 
-    # dumping to a file named ' ' so that the ssh-keygen output
-    # doesn't claim any potentially bogus hostname(s):
-    tmpkey=$(mktemp ${TMPDIR:-/tmp}/tmp.XXXXXXXXXX) || failure "Could not create temporary directory!"
-    gpg_authentication "--export $fingerprint" | openpgp2ssh "$fingerprint" 2>/dev/null > "$tmpkey"
+    # do some crazy "Here Strings" redirection to get the key to
+    # ssh-keygen, since it doesn't read from stdin cleanly
     echo -n "ssh fingerprint: "
-    ssh-keygen -l -f $tmpkey | awk '{ print $1, $2, $4 }'
-    rm -rf "$tmpkey"
+    ssh-keygen -l -f /dev/stdin \
+	<<<$(gpg_authentication "--export $fingerprint" | \
+	openpgp2ssh "$fingerprint" 2>/dev/null) | \
+	awk '{ print $1, $2, $4 }'
     echo -n "OpenPGP fingerprint: "
     echo "$fingerprint"
 }
@@ -399,7 +399,11 @@ EOF
     (umask 077 && \
 	gpg_host --export-secret-key "$fingerprint" | \
 	openpgp2ssh "$fingerprint" > "${SYSDATADIR}/ssh_host_rsa_key")
-    log info "private SSH host key output to file: ${SYSDATADIR}/ssh_host_rsa_key"
+    log info "SSH host private key output to file: ${SYSDATADIR}/ssh_host_rsa_key"
+    ssh-keygen -y -f "${SYSDATADIR}/ssh_host_rsa_key" > "${SYSDATADIR}/ssh_host_rsa_key.pub"
+    log info "SSH host public key output to file: ${SYSDATADIR}/ssh_host_rsa_key.pub"
+    gpg_authentication "--export-options export-minimal --armor --export 0x${fingerprint}\!" > "${SYSDATADIR}/ssh_host_rsa_key.pub.gpg"
+    log info "SSH host public key in OpenPGP form: ${SYSDATADIR}/ssh_host_rsa_key.pub.gpg"
 }
 
 # extend the lifetime of a host key:
diff --git a/src/monkeysphere-ssh-proxycommand b/src/monkeysphere-ssh-proxycommand
index 6276092..a609199 100755
--- a/src/monkeysphere-ssh-proxycommand
+++ b/src/monkeysphere-ssh-proxycommand
@@ -14,13 +14,129 @@
 #  ProxyCommand monkeysphere-ssh-proxycommand %h %p
 
 ########################################################################
+PGRM=$(basename $0)
+
+SYSSHAREDIR=${MONKEYSPHERE_SYSSHAREDIR:-"/usr/share/monkeysphere"}
+export SYSSHAREDIR
+. "${SYSSHAREDIR}/common" || exit 1
+
+########################################################################
+# FUNCTIONS
+########################################################################
 
 usage() {
-cat <<EOF >&2
+    cat <<EOF >&2
 usage: ssh -o ProxyCommand="$(basename $0) %h %p" ...
 EOF
 }
 
+log() {
+    echo "$@" >&2
+}
+
+output_no_valid_key() {
+    local sshKeyOffered
+    local userID
+    local type
+    local validity
+    local keyid
+    local uidfpr
+    local usage
+    local sshKeyGPG
+    local tmpkey
+    local sshFingerprint
+    local gpgSigOut
+
+    userID="ssh://${HOSTP}"
+
+    log "-------------------- Monkeysphere warning -------------------"
+    log "Monkeysphere found OpenPGP keys for this hostname, but none had full validity."
+
+    # retrieve the actual ssh key
+    sshKeyOffered=$(ssh-keyscan -t rsa -p "$PORT" "$HOST" 2>/dev/null | awk '{ print $2, $3 }')
+    # FIXME: should we do any checks for failed keyscans, eg. host not
+    # found?
+
+    # get the gpg info for userid
+    gpgOut=$(gpg --list-key --fixed-list-mode --with-colon \
+	--with-fingerprint --with-fingerprint \
+	="$userID" 2>/dev/null)
+
+    # find all 'pub' and 'sub' lines in the gpg output, which each
+    # represent a retrieved key for the user ID
+    echo "$gpgOut" | cut -d: -f1,2,5,10,12 | \
+    while IFS=: read -r type validity keyid uidfpr usage ; do
+	case $type in
+	    'pub'|'sub')
+		# get the ssh key of the gpg key
+		sshKeyGPG=$(gpg2ssh "$keyid")
+
+		# if one of keys found matches the one offered by the
+		# host, then output info
+		if [ "$sshKeyGPG" = "$sshKeyOffered" ] ; then
+		    log "An OpenPGP key matching the ssh key offered by the host was found:"
+		    log
+
+		    # do some crazy "Here Strings" redirection to get the key to
+		    # ssh-keygen, since it doesn't read from stdin cleanly
+		    sshFingerprint=$(ssh-keygen -l -f /dev/stdin \
+			<<<$(echo "$sshKeyGPG") | \
+			awk '{ print $2 }')
+
+		    # get the sigs for the matching key
+		    gpgSigOut=$(gpg --check-sigs \
+			--list-options show-uid-validity \
+			"$keyid")
+
+		    # output the sigs, but only those on the user ID
+		    # we are looking for
+		    echo "$gpgSigOut" | awk '
+{
+if (match($0,"^pub")) {	print; }
+if (match($0,"^uid")) { ok=0; }
+if (match($0,"^uid.*'$userID'$")) { ok=1; print; }
+if (ok) { if (match($0,"^sig")) { print; } }
+}
+' >&2
+		    log
+
+		    # output the other user IDs for reference
+		    if (echo "$gpgSigOut" | grep "^uid" | grep -v -q "$userID") ; then
+			log "Other user IDs on this key:"
+			echo "$gpgSigOut" | grep "^uid" | grep -v "$userID" >&2
+			log
+		    fi
+
+		    # output ssh fingerprint
+		    log "RSA key fingerprint is ${sshFingerprint}."
+
+		    # this whole process is in a "while read"
+		    # subshell.  the only way to get information out
+		    # of the subshell is to change the return code.
+		    # therefore we return 1 here to indicate that a
+		    # matching gpg key was found for the ssh key
+		    # offered by the host
+		    return 1
+		fi
+		;;
+	esac
+    done
+
+    # if no key match was made (and the "while read" subshell returned
+    # 1) output how many keys were found
+    if (($? != 1)) ; then
+	log "None of the found keys matched the key offered by the host."
+	log "Run the following command for more info about the found keys:"
+	log "gpg --check-sigs --list-options show-uid-validity =${userID}"
+	# FIXME: should we do anything extra here if the retrieved
+	# host key is actually in the known_hosts file and the ssh
+	# connection will succeed?  Should the user be warned?
+	# prompted?
+    fi
+
+    log "-------------------- ssh continues below --------------------"
+}
+
 ########################################################################
 
 # export the monkeysphere log level
@@ -35,7 +151,7 @@ HOST="$1"
 PORT="$2"
 
 if [ -z "$HOST" ] ; then
-    echo "Host not specified." >&2
+    log "Host not specified."
     usage
     exit 255
 fi
@@ -88,6 +204,39 @@ export MONKEYSPHERE_CHECK_KEYSERVER
 # update the known_hosts file for the host
 monkeysphere update-known_hosts "$HOSTP"
 
+# output on depending on the return of the update-known_hosts
+# subcommand, which is (ultimately) the return code of the
+# update_known_hosts function in common
+case $? in
+    0)
+	# acceptable host key found so continue to ssh
+	true
+	;;
+    1)
+	# no hosts at all found so also continue (drop through to
+	# regular ssh host verification)
+	true
+	;;
+    2)
+	# at least one *bad* host key (and no good host keys) was
+	# found, so output some usefull information
+	output_no_valid_key
+	;;
+    *)
+	# anything else drop through
+	true
+	;;
+esac
+
+# FIXME: what about the case where monkeysphere successfully finds a
+# valid key for the host and adds it to the known_hosts file, but a
+# different non-monkeysphere key for the host already exists in the
+# known_hosts, and it is this non-ms key that is offered by the host?
+# monkeysphere will succeed, and the ssh connection will succeed, and
+# the user will be left with the impression that they are dealing with
+# a OpenPGP/PKI host key when in fact they are not.  should we use
+# ssh-keyscan to compare the keys first?
+
 # exec a netcat passthrough to host for the ssh connection
 if [ -z "$NO_CONNECT" ] ; then
     if (which nc 2>/dev/null >/dev/null); then
diff --git a/utils/build-releasenote b/utils/build-releasenote
index 522917c..b25a87c 100755
--- a/utils/build-releasenote
+++ b/utils/build-releasenote
@@ -4,7 +4,7 @@ VERSION=`head -n1 packaging/debian/changelog | sed 's/.*(\([^)]*\)).*/\1/'`
 
 { 
     sed "s/__VERSION__/$VERSION/g" < utils/releasenote.header
-    head -n$(( $(grep -n '^ --' debian/changelog  | head -n1 | cut -f1 -d:) - 2 )) debian/changelog | tail -n+3
+    head -n$(( $(grep -n '^ --' packaging/debian/changelog  | head -n1 | cut -f1 -d:) - 2 )) packaging/debian/changelog | tail -n+3
     sed "s/__VERSION__/$VERSION/g" < utils/releasenote.footer
 } > "website/news/release-$VERSION.mdwn"
 
diff --git a/website/bugs/useful-information.mdwn b/website/bugs/useful-information.mdwn
deleted file mode 100644
index 0750354..0000000
--- a/website/bugs/useful-information.mdwn
+++ /dev/null
@@ -1,10 +0,0 @@
-I would like to know, at INFO (default) log level, when the 
-monkeyspehere makes a "real" modification to my known_hosts file; that 
-is, when it adds or deletes a key.
-
-Apparently this is hard because monkeysphere is currently configured to 
-delete all keys and then add good keys, so a key added for the first 
-time seems to the monkeysphere very similar to a key re-added ten 
-seconds after last login.
-
-Still, from a UI perspective, I want to know what monkeysphere is doing.
diff --git a/website/bugs/useful_information.mdwn b/website/bugs/useful_information.mdwn
new file mode 100644
index 0000000..025d678
--- /dev/null
+++ b/website/bugs/useful_information.mdwn
@@ -0,0 +1,50 @@
+I would like to know, at INFO (default) log level, when the 
+monkeyspehere makes a "real" modification to my known\_hosts file; that 
+is, when it adds or deletes a key.
+
+Apparently this is hard because monkeysphere is currently configured to 
+delete all keys and then add good keys, so a key added for the first 
+time seems to the monkeysphere very similar to a key re-added ten 
+seconds after last login.
+
+Still, from a UI perspective, I want to know what monkeysphere is doing.
+
+------
+
+It looks like jrollins committed a change for reporting at INFO level
+when a host key gets added by the monkeysphere:
+2459fa3ea277d7b9289945748619eab1e3441e5c
+
+When i connect to a host whose key is not already present in my
+known_hosts file, i get the following to stderr:
+
+    ms: * new key for squeak.fifthhorseman.net added to known_hosts file.
+
+This doesn't fully close this bug, because we aren't notifying on key
+deletion, afaict.
+
+------
+
+So current log level DEBUG will output a message if the known host
+file has been modified.  If the issue is that you want to know at the
+default log level everytime the known\_hots file is modified, then we
+should just move this message to INFO instead of debug, and then maybe
+remove the message that I added above.  I was under the impression
+that the issue was more about notification that a *new* key was added
+to the known\_hosts file, and therefore the new INFO message above
+fixed that problem.  Should we do this instead?
+
+In general, more verbose log levels *do* tell the user what the
+monkeysphere is doing.  Moving to DEBUG log level will tell you pretty
+much everything that happens.  I do *not* think that this should be
+the default log level, though.
+
+------
+
+I wouldn't want to see an extremely verbose default log level.  But i
+do think that saying something like "key blah blah blah was stripped
+from your known\_hosts file because it was expired" (for example)
+would be useful.  I think this case would occur infrequently enough
+that it is worth reporting in the UI at the regular log level.
+
+  --dkg
diff --git a/website/doc.mdwn b/website/doc.mdwn
index b60cf28..02b4184 100644
--- a/website/doc.mdwn
+++ b/website/doc.mdwn
@@ -8,6 +8,10 @@
  * Getting started as a [user](/getting-started-user)
  * Getting started as a [server admin](/getting-started-admin)
 
+## Going further ##
+
+ * [Signing server keys](/signing-server-keys)
+
 ## Under the hood ##
 
  * [Developing the monkeysphere](/community)
@@ -15,7 +19,7 @@
 
 ## References ##
 
- * [Initial specifications at CMRG](http://cmrg.fifthhorseman.net/wiki/OpenPGPandSSH)
+ * [Initial Monkeysphere specifications at CMRG](http://cmrg.fifthhorseman.net/wiki/OpenPGPandSSH)
  * [OpenPGP (RFC 4880)](http://tools.ietf.org/html/rfc4880)
  * [Secure Shell Authentication Protocol (RFC 4252)](http://tools.ietf.org/html/rfc4252)
    * [URI scheme for SSH, RFC draft](http://tools.ietf.org/wg/secsh/draft-ietf-secsh-scp-sftp-ssh-uri/)
diff --git a/website/getting-started-admin.mdwn b/website/getting-started-admin.mdwn
index 6c8ad53..1c373ac 100644
--- a/website/getting-started-admin.mdwn
+++ b/website/getting-started-admin.mdwn
@@ -7,6 +7,7 @@ so that your users can have it automatically verified, and you can set
 up your machine to automatically identify connecting users by their
 presence in the OpenPGP web of trust.
 
+
 Server host key publication
 ---------------------------
 To generate and publish a server host key:
@@ -48,6 +49,7 @@ effect.  As with any change to `sshd_config`, be sure to retain an
 existing session to the machine while you test your changes so you
 don't get locked out.
 
+
 Monkeysphere authorized_keys maintenance
 ----------------------------------------
 
diff --git a/website/getting-started-user.mdwn b/website/getting-started-user.mdwn
index 5dcb0d6..9b04edc 100644
--- a/website/getting-started-user.mdwn
+++ b/website/getting-started-user.mdwn
@@ -20,6 +20,7 @@ done with a simple cronjob.  An example of crontab line to do this is:
 
 This would refresh your keychain every day at noon.
 
+
 Install the monkeysphere software on your system
 ------------------------------------------------
 
@@ -31,8 +32,9 @@ installed on your system. If you can't (or don't want to) upgrade to
 GnuTLS 2.6 or later, there are patches for GnuTLS 2.4 available in
 [the Monkeysphere git repo](/community).
 
+
 Keeping your `known_hosts` file in sync with your keyring
------------------------------------------------------------
+---------------------------------------------------------
 
 With your keyring updated, you want to make sure that OpenSSH can
 still see the most recent trusted information about who the various
@@ -47,6 +49,7 @@ key for that host to the `known_hosts` file if one is found.  This
 command could be added to a crontab as well, if desired.
 
 
+
 Using `monkeysphere-ssh-proxycommand`(1)
 ----------------------------------------
 
@@ -91,6 +94,7 @@ If you have more than one secret key, you'll need to specify the key
 you want to add the subkey to on the command line.
 
 
+
 Using your OpenPGP authentication key for SSH
 ---------------------------------------------
 
@@ -105,6 +109,7 @@ you can feed your authentication subkey to your ssh agent by running:
 
 FIXME: using the key with a single ssh connection?
 
+
 Establish trust
 ---------------
 
diff --git a/website/signing-host-keys.mdwn b/website/signing-host-keys.mdwn
new file mode 100644
index 0000000..e0d26a7
--- /dev/null
+++ b/website/signing-host-keys.mdwn
@@ -0,0 +1,128 @@
+# Signing a server OpenPGP key #
+
+This page is meant to address the issue of signing server OpenPGP
+keys.  Servers are not people, so the circumstances under which one
+should sign a server key are different from those under which one
+should sign another person's key.
+
+# Why are signatures on the server key important? #
+
+In order for users to connect to a server in a monkeysphere-enabled
+network, the server key must have *full* calculated validity from the
+perspective of the connecting user.  If the user has not themselves
+signed the server's key, then the server's key can only be valid if
+other people that the user trusts have signed the key.
+
+If only one person has signed the server's key, then the user must
+fully trust the single person who has signed the server key.  Full
+trust should be granted sparingly and with consideration, though, so
+unless the user knows the server admin very well, they will in general
+not have full trust of this person.
+
+However, full trust of the server key can also be achieved if the
+server key has been signed by three or more people that the user has
+ *marginal* trust of.  In other words, three or more *marginally*
+trusted signatures equals one *fully* trusted signature.  It is much
+more common for users to have marginal trust of other users in the Web
+of Trust.  For this reason, it is advisable to have as many people
+sign the server key as possible.
+
+## What information should you have before signing a server key? ##
+
+Before signing the key of a person, you want to do two things:
+
+1. verify the identity of the person.
+2. verify that the person is actually in control of the key that you
+are signing.
+
+For a server, you want to do basically the same thing:
+
+1. verify the identity of the server.
+2. verify that the server is actually in control of the key that you
+are signing.
+
+However, with a server, verifying these things is a little trickier.
+
+Verifying that the server is in control of the key is, in principle,
+straightforward.  If you are logged on to the machine in question,
+then you can check directly that the key exists on the system.
+
+What is not so straightforward is what exactly it means to "verify the
+identity" of a remote server on the internet?  The identity in this
+case is the fully qualified domain name (FQDN) of the host.  Verifying
+this identity amounts to being sure that the host in question really
+is located at that FQDN.
+
+
+## Signing the server key ##
+
+If you are the person (or persons) that actually setup the server and
+configured Monkeysphere and ssh on the server, then clearly you should
+definitely sign the server key right away.  When the server is first
+setup, the persons who set it up are the only ones who can actually
+vouch for the server key, so their signatures are necessary to get
+things going.  Their signatures are also necessary so that they can
+verify the host key themselves and log into the server via
+monkeysphere-enabled ssh in the future.
+
+If you did not set up the server initially, you do not have an
+accumulated full trust of the person(s) who did, and you do not
+necessarily have console access to the server directly, it's hard to
+confidently verify the server identity and key ownership.  You would
+like to be able to walk up to the server, log in at the console, and
+get the fingerprint of the ssh host key directly.  But this is usually
+untenable.
+
+However, it is still possible to verify the server identity *and*
+server ownership of the key, even in this case.
+
+
+## Remotely verifying server identify and key possession ##
+
+It is in fact possible to verify the identity and key ownership of a
+server in one fell swoop with monkeysphere-enabled ssh.  Here is the
+procedure:
+
+> **Attempt to make a monkeysphere-enabled ssh connection to the host in
+question.  Monkeysphere will check that the ssh host key offered by the
+host matches the OpenPGP key with the correct host FQDN user ID.  If
+the ssh host key and the OpenPGP key with the correct user ID match,
+then you will have effectively:**
+
+>**1. verified the host identity, because you actually connected to the
+host in question, which you know because you:**
+
+>**2. verified the host is in control of the key, because the ssh host
+key offered by the host matches the OpenPGP key with correct host FQDN
+user ID.**
+
+Here is an example:
+
+	servo:~ 0$ ssh zimmermann.mayfirst.org
+	-------------------- Monkeysphere warning -------------------
+	Monkeysphere found OpenPGP keys for this hostname, but none had full validity.
+	An OpenPGP key matching the ssh key offered by the host was found:
+	
+	pub   2048R/860E8F9C 2008-10-29 [expires: 2009-02-26]
+	uid       [marginal] ssh://zimmermann.mayfirst.org
+	sig!         76CC057D 2008-11-15  Jamie McClelland <jamie@mayfirst.org>
+	sig!3        860E8F9C 2008-10-29  ssh://zimmermann.mayfirst.org
+	sig!         D21739E9 2008-10-29  Daniel Kahn Gillmor <dkg@fifthhorseman.net>
+	sig!         1CF2D62A 2008-11-16  Micah Anderson <micah@riseup.net>
+	
+	RSA key fingerprint is 81:96:13:3e:24:c9:3c:5b:3c:6d:55:ba:58:85:e9:9e.
+	-------------------- ssh continues below --------------------
+	The authenticity of host 'zimmermann.mayfirst.org (<no hostip for proxy command>)' can't be established.
+	RSA key fingerprint is 81:96:13:3e:24:c9:3c:5b:3c:6d:55:ba:58:85:e9:9e.
+	No matching host key fingerprint found in DNS.
+	Are you sure you want to continue connecting (yes/no)? no
+	Host key verification failed.
+	servo:~ 255$ 
+
+I have attempted to connect to the host zimmermann.mayfirst.org.
+zimmermann's host key has only *marginal* validity for the FQDN user
+ID in question, so I am not able to connect.  However, the
+monkeysphere has checked that the ssh host key actually does match the
+OpenPGP key with the correct user ID `ssh://zimmermann.mayfirst.org`.
+I have therefore verified the identity of zimmermann, and verified
+that zimmermann is in possession of the key in question.