9 files changed, 166 insertions, 131 deletions

diff --git a/usr.bin/ssh/ssh-dss.c b/usr.bin/ssh/ssh-dss.c
index 6b2c48750c8..2dba1ed1d2c 100644
--- a/usr.bin/ssh/ssh-dss.c
+++ b/usr.bin/ssh/ssh-dss.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-dss.c,v 1.43 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: ssh-dss.c,v 1.44 2022/10/28 00:41:17 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -136,6 +136,43 @@ ssh_dss_generate(struct sshkey *k, int bits)
 	return 0;
 }
 
+static int
+ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
+	BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
+	BIGNUM *dsa_pub_key_dup = NULL;
+	int r = SSH_ERR_INTERNAL_ERROR;
+
+	DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g);
+	DSA_get0_key(from->dsa, &dsa_pub_key, NULL);
+	if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
+	    (dsa_q_dup = BN_dup(dsa_q)) == NULL ||
+	    (dsa_g_dup = BN_dup(dsa_g)) == NULL ||
+	    (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
+		r = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
+	if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) {
+		r = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	dsa_pub_key_dup = NULL; /* transferred */
+	/* success */
+	r = 0;
+ out:
+	BN_clear_free(dsa_p_dup);
+	BN_clear_free(dsa_q_dup);
+	BN_clear_free(dsa_g_dup);
+	BN_clear_free(dsa_pub_key_dup);
+	return r;
+}
+
 int
 ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat)
@@ -300,6 +337,7 @@ static const struct sshkey_impl_funcs sshkey_dss_funcs = {
 	/* .equal = */		ssh_dss_equal,
 	/* .ssh_serialize_public = */ ssh_dss_serialize_public,
 	/* .generate = */	ssh_dss_generate,
+	/* .copy_public = */	ssh_dss_copy_public,
 };
 
 const struct sshkey_impl sshkey_dss_impl = {
diff --git a/usr.bin/ssh/ssh-ecdsa-sk.c b/usr.bin/ssh/ssh-ecdsa-sk.c
index 5c844d8baac..f3692b0b7fb 100644
--- a/usr.bin/ssh/ssh-ecdsa-sk.c
+++ b/usr.bin/ssh/ssh-ecdsa-sk.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-ecdsa-sk.c,v 1.12 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: ssh-ecdsa-sk.c,v 1.13 2022/10/28 00:41:17 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -78,6 +78,18 @@ ssh_ecdsa_sk_serialize_public(const struct sshkey *key, struct sshbuf *b,
 	return 0;
 }
 
+static int
+ssh_ecdsa_sk_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	int r;
+
+	if ((r = sshkey_ecdsa_funcs.copy_public(from, to)) != 0)
+		return r;
+	if ((r = sshkey_copy_public_sk(from, to)) != 0)
+		return r;
+	return 0;
+}
+
 /*
  * Check FIDO/W3C webauthn signatures clientData field against the expected
  * format and prepare a hash of it for use in signature verification.
@@ -345,6 +357,7 @@ static const struct sshkey_impl_funcs sshkey_ecdsa_sk_funcs = {
 	/* .equal = */		ssh_ecdsa_sk_equal,
 	/* .ssh_serialize_public = */ ssh_ecdsa_sk_serialize_public,
 	/* .generate = */	NULL,
+	/* .copy_public = */	ssh_ecdsa_sk_copy_public,
 };
 
 const struct sshkey_impl sshkey_ecdsa_sk_impl = {
diff --git a/usr.bin/ssh/ssh-ecdsa.c b/usr.bin/ssh/ssh-ecdsa.c
index 9e576648354..b2b03205d13 100644
--- a/usr.bin/ssh/ssh-ecdsa.c
+++ b/usr.bin/ssh/ssh-ecdsa.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-ecdsa.c,v 1.20 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: ssh-ecdsa.c,v 1.21 2022/10/28 00:41:17 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -118,6 +118,18 @@ ssh_ecdsa_generate(struct sshkey *k, int bits)
 	return 0;
 }
 
+static int
+ssh_ecdsa_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	to->ecdsa_nid = from->ecdsa_nid;
+	if ((to->ecdsa = EC_KEY_new_by_curve_name(from->ecdsa_nid)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if (EC_KEY_set_public_key(to->ecdsa,
+	    EC_KEY_get0_public_key(from->ecdsa)) != 1)
+		return SSH_ERR_LIBCRYPTO_ERROR; /* caller will free k->ecdsa */
+	return 0;
+}
+
 /* ARGSUSED */
 int
 ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
@@ -278,6 +290,7 @@ const struct sshkey_impl_funcs sshkey_ecdsa_funcs = {
 	/* .equal = */		ssh_ecdsa_equal,
 	/* .ssh_serialize_public = */ ssh_ecdsa_serialize_public,
 	/* .generate = */	ssh_ecdsa_generate,
+	/* .copy_public = */	ssh_ecdsa_copy_public,
 };
 
 const struct sshkey_impl sshkey_ecdsa_nistp256_impl = {
diff --git a/usr.bin/ssh/ssh-ed25519-sk.c b/usr.bin/ssh/ssh-ed25519-sk.c
index 7131363f4a2..99676d96a84 100644
--- a/usr.bin/ssh/ssh-ed25519-sk.c
+++ b/usr.bin/ssh/ssh-ed25519-sk.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-ed25519-sk.c,v 1.10 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: ssh-ed25519-sk.c,v 1.11 2022/10/28 00:41:17 djm Exp $ */
 /*
  * Copyright (c) 2019 Markus Friedl.  All rights reserved.
  *
@@ -68,6 +68,18 @@ ssh_ed25519_sk_serialize_public(const struct sshkey *key, struct sshbuf *b,
 	return 0;
 }
 
+static int
+ssh_ed25519_sk_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	int r;
+
+	if ((r = sshkey_ed25519_funcs.copy_public(from, to)) != 0)
+		return r;
+	if ((r = sshkey_copy_public_sk(from, to)) != 0)
+		return r;
+	return 0;
+}
+
 int
 ssh_ed25519_sk_verify(const struct sshkey *key,
     const u_char *signature, size_t signaturelen,
@@ -202,6 +214,7 @@ static const struct sshkey_impl_funcs sshkey_ed25519_sk_funcs = {
 	/* .equal = */		ssh_ed25519_sk_equal,
 	/* .ssh_serialize_public = */ ssh_ed25519_sk_serialize_public,
 	/* .generate = */	NULL,
+	/* .copy_public = */	ssh_ed25519_sk_copy_public,
 };
 
 const struct sshkey_impl sshkey_ed25519_sk_impl = {
diff --git a/usr.bin/ssh/ssh-ed25519.c b/usr.bin/ssh/ssh-ed25519.c
index bbf164c8c42..db1dc96f379 100644
--- a/usr.bin/ssh/ssh-ed25519.c
+++ b/usr.bin/ssh/ssh-ed25519.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-ed25519.c,v 1.14 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: ssh-ed25519.c,v 1.15 2022/10/28 00:41:17 djm Exp $ */
 /*
  * Copyright (c) 2013 Markus Friedl <markus@openbsd.org>
  *
@@ -73,6 +73,17 @@ ssh_ed25519_generate(struct sshkey *k, int bits)
 	return 0;
 }
 
+static int
+ssh_ed25519_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	if (from->ed25519_pk == NULL)
+		return 0; /* XXX SSH_ERR_INTERNAL_ERROR ? */
+	if ((to->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	memcpy(to->ed25519_pk, from->ed25519_pk, ED25519_PK_SZ);
+	return 0;
+}
+
 int
 ssh_ed25519_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat)
@@ -208,6 +219,7 @@ const struct sshkey_impl_funcs sshkey_ed25519_funcs = {
 	/* .equal = */		ssh_ed25519_equal,
 	/* .ssh_serialize_public = */ ssh_ed25519_serialize_public,
 	/* .generate = */	ssh_ed25519_generate,
+	/* .copy_public = */	ssh_ed25519_copy_public,
 };
 
 const struct sshkey_impl sshkey_ed25519_impl = {
diff --git a/usr.bin/ssh/ssh-rsa.c b/usr.bin/ssh/ssh-rsa.c
index f6aa4bfef63..f13a082555b 100644
--- a/usr.bin/ssh/ssh-rsa.c
+++ b/usr.bin/ssh/ssh-rsa.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-rsa.c,v 1.72 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: ssh-rsa.c,v 1.73 2022/10/28 00:41:17 djm Exp $ */
 /*
  * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
  *
@@ -125,6 +125,32 @@ ssh_rsa_generate(struct sshkey *k, int bits)
 	return ret;
 }
 
+static int
+ssh_rsa_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	const BIGNUM *rsa_n, *rsa_e;
+	BIGNUM *rsa_n_dup = NULL, *rsa_e_dup = NULL;
+	int r = SSH_ERR_INTERNAL_ERROR;
+
+	RSA_get0_key(from->rsa, &rsa_n, &rsa_e, NULL);
+	if ((rsa_n_dup = BN_dup(rsa_n)) == NULL ||
+	    (rsa_e_dup = BN_dup(rsa_e)) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if (!RSA_set0_key(to->rsa, rsa_n_dup, rsa_e_dup, NULL)) {
+		r = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	rsa_n_dup = rsa_e_dup = NULL; /* transferred */
+	/* success */
+	r = 0;
+ out:
+	BN_clear_free(rsa_n_dup);
+	BN_clear_free(rsa_e_dup);
+	return r;
+}
+
 static const char *
 rsa_hash_alg_ident(int hash_alg)
 {
@@ -540,6 +566,7 @@ static const struct sshkey_impl_funcs sshkey_rsa_funcs = {
 	/* .equal = */		ssh_rsa_equal,
 	/* .ssh_serialize_public = */ ssh_rsa_serialize_public,
 	/* .generate = */	ssh_rsa_generate,
+	/* .copy_public = */	ssh_rsa_copy_public,
 };
 
 const struct sshkey_impl sshkey_rsa_impl = {
diff --git a/usr.bin/ssh/ssh-xmss.c b/usr.bin/ssh/ssh-xmss.c
index 30cd89c7f1b..7a3bec7c7f0 100644
--- a/usr.bin/ssh/ssh-xmss.c
+++ b/usr.bin/ssh/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.
@@ -79,6 +79,31 @@ 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)
@@ -234,6 +259,7 @@ 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 = {
diff --git a/usr.bin/ssh/sshkey.c b/usr.bin/ssh/sshkey.c
index 74ee6b4409a..7a6daeb8a6d 100644
--- a/usr.bin/ssh/sshkey.c
+++ b/usr.bin/ssh/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.127 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: sshkey.c,v 1.128 2022/10/28 00:41:17 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -1406,130 +1406,30 @@ sshkey_cert_copy(const struct sshkey *from_key, struct sshkey *to_key)
 }
 
 int
+sshkey_copy_public_sk(const struct sshkey *from, struct sshkey *to)
+{
+	/* Append security-key application string */
+	if ((to->sk_application = strdup(from->sk_application)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	return 0;
+}
+
+int
 sshkey_from_private(const struct sshkey *k, struct sshkey **pkp)
 {
 	struct sshkey *n = NULL;
 	int r = SSH_ERR_INTERNAL_ERROR;
-#ifdef WITH_OPENSSL
-	const BIGNUM *rsa_n, *rsa_e;
-	BIGNUM *rsa_n_dup = NULL, *rsa_e_dup = NULL;
-	const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
-	BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
-	BIGNUM *dsa_pub_key_dup = NULL;
-#endif /* WITH_OPENSSL */
+	const struct sshkey_impl *impl;
 
 	*pkp = NULL;
+	if ((impl = sshkey_impl_from_key(k)) == NULL)
+		return SSH_ERR_KEY_TYPE_UNKNOWN;
 	if ((n = sshkey_new(k->type)) == NULL) {
 		r = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}
-	switch (k->type) {
-#ifdef WITH_OPENSSL
-	case KEY_DSA:
-	case KEY_DSA_CERT:
-		DSA_get0_pqg(k->dsa, &dsa_p, &dsa_q, &dsa_g);
-		DSA_get0_key(k->dsa, &dsa_pub_key, NULL);
-		if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
-		    (dsa_q_dup = BN_dup(dsa_q)) == NULL ||
-		    (dsa_g_dup = BN_dup(dsa_g)) == NULL ||
-		    (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
-		if (!DSA_set0_pqg(n->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
-			r = SSH_ERR_LIBCRYPTO_ERROR;
-			goto out;
-		}
-		dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
-		if (!DSA_set0_key(n->dsa, dsa_pub_key_dup, NULL)) {
-			r = SSH_ERR_LIBCRYPTO_ERROR;
-			goto out;
-		}
-		dsa_pub_key_dup = NULL; /* transferred */
-
-		break;
-	case KEY_ECDSA:
-	case KEY_ECDSA_CERT:
-	case KEY_ECDSA_SK:
-	case KEY_ECDSA_SK_CERT:
-		n->ecdsa_nid = k->ecdsa_nid;
-		n->ecdsa = EC_KEY_new_by_curve_name(k->ecdsa_nid);
-		if (n->ecdsa == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
-		if (EC_KEY_set_public_key(n->ecdsa,
-		    EC_KEY_get0_public_key(k->ecdsa)) != 1) {
-			r = SSH_ERR_LIBCRYPTO_ERROR;
-			goto out;
-		}
-		if (k->type != KEY_ECDSA_SK && k->type != KEY_ECDSA_SK_CERT)
-			break;
-		/* Append security-key application string */
-		if ((n->sk_application = strdup(k->sk_application)) == NULL)
-			goto out;
-		break;
-	case KEY_RSA:
-	case KEY_RSA_CERT:
-		RSA_get0_key(k->rsa, &rsa_n, &rsa_e, NULL);
-		if ((rsa_n_dup = BN_dup(rsa_n)) == NULL ||
-		    (rsa_e_dup = BN_dup(rsa_e)) == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
-		if (!RSA_set0_key(n->rsa, rsa_n_dup, rsa_e_dup, NULL)) {
-			r = SSH_ERR_LIBCRYPTO_ERROR;
-			goto out;
-		}
-		rsa_n_dup = rsa_e_dup = NULL; /* transferred */
-		break;
-#endif /* WITH_OPENSSL */
-	case KEY_ED25519:
-	case KEY_ED25519_CERT:
-	case KEY_ED25519_SK:
-	case KEY_ED25519_SK_CERT:
-		if (k->ed25519_pk != NULL) {
-			if ((n->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) {
-				r = SSH_ERR_ALLOC_FAIL;
-				goto out;
-			}
-			memcpy(n->ed25519_pk, k->ed25519_pk, ED25519_PK_SZ);
-		}
-		if (k->type != KEY_ED25519_SK &&
-		    k->type != KEY_ED25519_SK_CERT)
-			break;
-		/* Append security-key application string */
-		if ((n->sk_application = strdup(k->sk_application)) == NULL)
-			goto out;
-		break;
-#ifdef WITH_XMSS
-	case KEY_XMSS:
-	case KEY_XMSS_CERT:
-		if ((r = sshkey_xmss_init(n, k->xmss_name)) != 0)
-			goto out;
-		if (k->xmss_pk != NULL) {
-			u_int32_t left;
-			size_t pklen = sshkey_xmss_pklen(k);
-			if (pklen == 0 || sshkey_xmss_pklen(n) != pklen) {
-				r = SSH_ERR_INTERNAL_ERROR;
-				goto out;
-			}
-			if ((n->xmss_pk = malloc(pklen)) == NULL) {
-				r = SSH_ERR_ALLOC_FAIL;
-				goto out;
-			}
-			memcpy(n->xmss_pk, k->xmss_pk, pklen);
-			/* simulate number of signatures left on pubkey */
-			left = sshkey_xmss_signatures_left(k);
-			if (left)
-				sshkey_xmss_enable_maxsign(n, left);
-		}
-		break;
-#endif /* WITH_XMSS */
-	default:
-		r = SSH_ERR_KEY_TYPE_UNKNOWN;
+	if ((r = impl->funcs->copy_public(k, n)) != 0)
 		goto out;
-	}
 	if (sshkey_is_cert(k) && (r = sshkey_cert_copy(k, n)) != 0)
 		goto out;
 	/* success */
@@ -1538,15 +1438,6 @@ sshkey_from_private(const struct sshkey *k, struct sshkey **pkp)
 	r = 0;
  out:
 	sshkey_free(n);
-#ifdef WITH_OPENSSL
-	BN_clear_free(rsa_n_dup);
-	BN_clear_free(rsa_e_dup);
-	BN_clear_free(dsa_p_dup);
-	BN_clear_free(dsa_q_dup);
-	BN_clear_free(dsa_g_dup);
-	BN_clear_free(dsa_pub_key_dup);
-#endif /* WITH_OPENSSL */
-
 	return r;
 }
 
diff --git a/usr.bin/ssh/sshkey.h b/usr.bin/ssh/sshkey.h
index c90724ac575..899614dbe30 100644
--- a/usr.bin/ssh/sshkey.h
+++ b/usr.bin/ssh/sshkey.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.h,v 1.56 2022/10/28 00:39:29 djm Exp $ */
+/* $OpenBSD: sshkey.h,v 1.57 2022/10/28 00:41:17 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -166,6 +166,7 @@ struct sshkey_impl_funcs {
 	int (*serialize_public)(const struct sshkey *, struct sshbuf *,
 	    const char *, enum sshkey_serialize_rep);
 	int (*generate)(struct sshkey *, int);	/* optional */
+	int (*copy_public)(const struct sshkey *, struct sshkey *);
 };
 
 struct sshkey_impl {
@@ -307,6 +308,7 @@ void	 sshkey_sig_details_free(struct sshkey_sig_details *);
 int	sshkey_sk_fields_equal(const struct sshkey *a, const struct sshkey *b);
 void	sshkey_sk_cleanup(struct sshkey *k);
 int	sshkey_serialize_sk(const struct sshkey *key, struct sshbuf *b);
+int	sshkey_copy_public_sk(const struct sshkey *from, struct sshkey *to);
 
 int ssh_rsa_sign(const struct sshkey *key,
     u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,