Index: readconf.c
===================================================================
RCS file: /home/cjwatson/cvs/openssh/openssh/readconf.c,v
retrieving revision 1.20
diff -p -u -r1.20 readconf.c
--- readconf.c	24 Dec 2007 10:29:57 -0000	1.20
+++ readconf.c	2 Jun 2008 12:43:01 -0000
@@ -125,6 +125,7 @@ typedef enum {
 	oGlobalKnownHostsFile2, oUserKnownHostsFile2, oPubkeyAuthentication,
 	oKbdInteractiveAuthentication, oKbdInteractiveDevices, oHostKeyAlias,
 	oDynamicForward, oPreferredAuthentications, oHostbasedAuthentication,
+	oUseBlacklistedKeys,
 	oHostKeyAlgorithms, oBindAddress, oSmartcardDevice,
 	oClearAllForwardings, oNoHostAuthenticationForLocalhost,
 	oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout,
@@ -155,6 +156,7 @@ static struct {
 	{ "passwordauthentication", oPasswordAuthentication },
 	{ "kbdinteractiveauthentication", oKbdInteractiveAuthentication },
 	{ "kbdinteractivedevices", oKbdInteractiveDevices },
+	{ "useblacklistedkeys", oUseBlacklistedKeys },
 	{ "rsaauthentication", oRSAAuthentication },
 	{ "pubkeyauthentication", oPubkeyAuthentication },
 	{ "dsaauthentication", oPubkeyAuthentication },		    /* alias */
@@ -448,6 +450,10 @@ parse_flag:
 		intptr = &options->challenge_response_authentication;
 		goto parse_flag;
 
+	case oUseBlacklistedKeys:
+		intptr = &options->use_blacklisted_keys;
+		goto parse_flag;
+
 	case oGssAuthentication:
 		intptr = &options->gss_authentication;
 		goto parse_flag;
@@ -1061,6 +1067,7 @@ initialize_options(Options * options)
 	options->kbd_interactive_devices = NULL;
 	options->rhosts_rsa_authentication = -1;
 	options->hostbased_authentication = -1;
+	options->use_blacklisted_keys = -1;
 	options->batch_mode = -1;
 	options->check_host_ip = -1;
 	options->strict_host_key_checking = -1;
@@ -1159,6 +1166,8 @@ fill_default_options(Options * options)
 		options->rhosts_rsa_authentication = 0;
 	if (options->hostbased_authentication == -1)
 		options->hostbased_authentication = 0;
+	if (options->use_blacklisted_keys == -1)
+		options->use_blacklisted_keys = 0;
 	if (options->batch_mode == -1)
 		options->batch_mode = 0;
 	if (options->check_host_ip == -1)
Index: readconf.h
===================================================================
RCS file: /home/cjwatson/cvs/openssh/openssh/readconf.h,v
retrieving revision 1.13
diff -p -u -r1.13 readconf.h
--- readconf.h	12 Jun 2007 16:16:34 -0000	1.13
+++ readconf.h	2 Jun 2008 12:43:01 -0000
@@ -51,6 +51,7 @@ typedef struct {
 						 * authentication. */
 	int     kbd_interactive_authentication; /* Try keyboard-interactive auth. */
 	char	*kbd_interactive_devices; /* Keyboard-interactive auth devices. */
+	int	use_blacklisted_keys;	/* If true, send */
 	int     batch_mode;	/* Batch mode: do not ask for passwords. */
 	int     check_host_ip;	/* Also keep track of keys for IP address */
 	int     strict_host_key_checking;	/* Strict host key checking. */
Index: ssh-add.c
===================================================================
RCS file: /home/cjwatson/cvs/openssh/openssh/ssh-add.c,v
retrieving revision 1.1.1.10
diff -p -u -r1.1.1.10 ssh-add.c
--- ssh-add.c	12 Jun 2007 11:03:21 -0000	1.1.1.10
+++ ssh-add.c	2 Jun 2008 12:43:01 -0000
@@ -138,7 +138,7 @@ static int
 add_file(AuthenticationConnection *ac, const char *filename)
 {
 	Key *private;
-	char *comment = NULL;
+	char *comment = NULL, *fp;
 	char msg[1024];
 	int fd, perms_ok, ret = -1;
 
@@ -183,6 +183,14 @@ add_file(AuthenticationConnection *ac, c
 			    "Bad passphrase, try again for %.200s: ", comment);
 		}
 	}
+	if (blacklisted_key(private, &fp) == 1) {
+		fprintf(stderr, "Public key %s blacklisted (see "
+		    "ssh-vulnkey(1)); refusing to add it\n", fp);
+		xfree(fp);
+		key_free(private);
+		xfree(comment);
+		return -1;
+	}
 
 	if (ssh_add_identity_constrained(ac, private, comment, lifetime,
 	    confirm)) {
Index: ssh.c
===================================================================
RCS file: /home/cjwatson/cvs/openssh/openssh/ssh.c,v
retrieving revision 1.16
diff -p -u -r1.16 ssh.c
--- ssh.c	24 Dec 2007 10:29:57 -0000	1.16
+++ ssh.c	2 Jun 2008 12:43:01 -0000
@@ -1218,7 +1218,7 @@ ssh_session2(void)
 static void
 load_public_identity_files(void)
 {
-	char *filename, *cp, thishost[NI_MAXHOST];
+	char *filename, *cp, thishost[NI_MAXHOST], *fp;
 	int i = 0;
 	Key *public;
 	struct passwd *pw;
@@ -1260,6 +1260,22 @@ load_public_identity_files(void)
 		public = key_load_public(filename, NULL);
 		debug("identity file %s type %d", filename,
 		    public ? public->type : -1);
+		if (blacklisted_key(public, &fp) == 1) {
+			if (options.use_blacklisted_keys)
+				logit("Public key %s blacklisted (see "
+				    "ssh-vulnkey(1)); continuing anyway", fp);
+			else
+				logit("Public key %s blacklisted (see "
+				    "ssh-vulnkey(1)); refusing to send it",
+				    fp);
+			xfree(fp);
+			if (!options.use_blacklisted_keys) {
+				key_free(public);
+				xfree(filename);
+				filename = NULL;
+				public = NULL;
+			}
+		}
 		xfree(options.identity_files[i]);
 		options.identity_files[i] = filename;
 		options.identity_keys[i] = public;
Index: ssh_config.5
===================================================================
RCS file: /home/cjwatson/cvs/openssh/openssh/ssh_config.5,v
retrieving revision 1.25
diff -p -u -r1.25 ssh_config.5
--- ssh_config.5	24 Dec 2007 13:02:05 -0000	1.25
+++ ssh_config.5	2 Jun 2008 12:43:01 -0000
@@ -1056,6 +1056,23 @@ is not specified, it defaults to
 .Dq any .
 The default is
 .Dq any:any .
+.It Cm UseBlacklistedKeys
+Specifies whether
+.Xr ssh 1
+should use keys recorded in its blacklist of known-compromised keys (see
+.Xr ssh-vulnkey 1 )
+for authentication.
+If
+.Dq yes ,
+then attempts to use compromised keys for authentication will be logged but
+accepted.
+It is strongly recommended that this be used only to install new authorized
+keys on the remote system, and even then only with the utmost care.
+If
+.Dq no ,
+then attempts to use compromised keys for authentication will be prevented.
+The default is
+.Dq no .
 .It Cm UsePrivilegedPort
 Specifies whether to use a privileged port for outgoing connections.
 The argument must be
Index: sshconnect2.c
===================================================================
RCS file: /home/cjwatson/cvs/openssh/openssh/sshconnect2.c,v
retrieving revision 1.12
diff -p -u -r1.12 sshconnect2.c
--- sshconnect2.c	24 Dec 2007 11:59:18 -0000	1.12
+++ sshconnect2.c	2 Jun 2008 12:43:02 -0000
@@ -1156,6 +1156,8 @@ pubkey_prepare(Authctxt *authctxt)
 
 	/* list of keys stored in the filesystem */
 	for (i = 0; i < options.num_identity_files; i++) {
+		if (options.identity_files[i] == NULL)
+			continue;
 		key = options.identity_keys[i];
 		if (key && key->type == KEY_RSA1)
 			continue;
@@ -1246,7 +1248,7 @@ userauth_pubkey(Authctxt *authctxt)
 		if (id->key && id->key->type != KEY_RSA1) {
 			debug("Offering public key: %s", id->filename);
 			sent = send_pubkey_test(authctxt, id);
-		} else if (id->key == NULL) {
+		} else if (id->key == NULL && id->filename) {
 			debug("Trying private key: %s", id->filename);
 			id->key = load_identity_file(id->filename);
 			if (id->key != NULL) {