upstream: refactor sshkey_from_private()

feedback/ok markus@

OpenBSD-Commit-ID: e5dbe7a3545930c50f70ee75c867a1e08b382b53

1 files changed, 27 insertions, 1 deletions

diff --git a/ssh-xmss.c b/ssh-xmss.c
index da8b4cc30..ef0fed167 100644
--- a/ssh-xmss.c
+++ b/ssh-xmss.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-xmss.c,v 1.9 2022/10/28 00:39:29 djm Exp $*/
+/* $OpenBSD: ssh-xmss.c,v 1.10 2022/10/28 00:41:17 djm Exp $*/
 /*
  * Copyright (c) 2017 Stefan-Lukas Gazdag.
  * Copyright (c) 2017 Markus Friedl.
@@ -82,6 +82,31 @@ ssh_xmss_serialize_public(const struct sshkey *key, struct sshbuf *b,
 	return 0;
 }
 
+static int
+ssh_xmss_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	int r = SSH_ERR_INTERNAL_ERROR;
+	u_int32_t left;
+	size_t pklen;
+
+	if ((r = sshkey_xmss_init(to, from->xmss_name)) != 0)
+		return r;
+	if (from->xmss_pk == NULL)
+		return 0; /* XXX SSH_ERR_INTERNAL_ERROR ? */
+
+	if ((pklen = sshkey_xmss_pklen(from)) == 0 ||
+	    sshkey_xmss_pklen(to) != pklen)
+		return SSH_ERR_INTERNAL_ERROR;
+	if ((to->xmss_pk = malloc(pklen)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	memcpy(to->xmss_pk, from->xmss_pk, pklen);
+	/* simulate number of signatures left on pubkey */
+	left = sshkey_xmss_signatures_left(from);
+	if (left)
+		sshkey_xmss_enable_maxsign(to, left);
+	return 0;
+}
+
 int
 ssh_xmss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat)
@@ -237,6 +262,7 @@ static const struct sshkey_impl_funcs sshkey_xmss_funcs = {
 	/* .equal = */		ssh_xmss_equal,
 	/* .ssh_serialize_public = */ ssh_xmss_serialize_public,
 	/* .generate = */	sshkey_xmss_generate_private_key,
+	/* .copy_public = */	ssh_xmss_copy_public,
 };
 
 const struct sshkey_impl sshkey_xmss_impl = {