upstream: Initial infrastructure for U2F/FIDO support

Key library support: including allocation, marshalling public/private
keys and certificates, signature validation.

feedback & ok markus@

OpenBSD-Commit-ID: a17615ba15e0f7932ac4360cb18fc9a9544e68c7

5 files changed, 381 insertions, 29 deletions

diff --git a/Makefile.in b/Makefile.in
index adb1977e..f22c8367 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -91,7 +91,8 @@ LIBSSH_OBJS=${LIBOPENSSH_OBJS} \
 	log.o match.o moduli.o nchan.o packet.o \
 	readpass.o ttymodes.o xmalloc.o addrmatch.o \
 	atomicio.o dispatch.o mac.o misc.o utf8.o \
-	monitor_fdpass.o rijndael.o ssh-dss.o ssh-ecdsa.o ssh-rsa.o dh.o \
+	monitor_fdpass.o rijndael.o ssh-dss.o ssh-ecdsa.o ssh-ecdsa-sk.o \
+	ssh-rsa.o dh.o \
 	msg.o progressmeter.o dns.o entropy.o gss-genr.o umac.o umac128.o \
 	ssh-pkcs11.o smult_curve25519_ref.o \
 	poly1305.o chacha.o cipher-chachapoly.o \
diff --git a/pathnames.h b/pathnames.h
index cb44caa4..2e0c7b15 100644
--- a/pathnames.h
+++ b/pathnames.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: pathnames.h,v 1.28 2018/02/23 15:58:37 markus Exp $ */
+/* $OpenBSD: pathnames.h,v 1.29 2019/10/31 21:15:14 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -77,6 +77,7 @@
 #define _PATH_SSH_CLIENT_ID_RSA		_PATH_SSH_USER_DIR "/id_rsa"
 #define _PATH_SSH_CLIENT_ID_ED25519	_PATH_SSH_USER_DIR "/id_ed25519"
 #define _PATH_SSH_CLIENT_ID_XMSS	_PATH_SSH_USER_DIR "/id_xmss"
+#define _PATH_SSH_CLIENT_ID_ECDSA_SK	_PATH_SSH_USER_DIR "/id_ecdsa_sk"
 
 /*
  * Configuration file in user's home directory.  This file need not be
diff --git a/ssh-ecdsa-sk.c b/ssh-ecdsa-sk.c
new file mode 100644
index 00000000..6441cd7f
--- /dev/null
+++ b/ssh-ecdsa-sk.c
@@ -0,0 +1,180 @@
+/* $OpenBSD: ssh-ecdsa-sk.c,v 1.1 2019/10/31 21:15:14 djm Exp $ */
+/*
+ * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2010 Damien Miller.  All rights reserved.
+ * Copyright (c) 2019 Google Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* #define DEBUG_SK 1 */
+
+#include "includes.h"
+
+#include <sys/types.h>
+
+#include <openssl/bn.h>
+#include <openssl/ec.h>
+#include <openssl/ecdsa.h>
+#include <openssl/evp.h>
+
+#include <string.h>
+#include <stdio.h> /* needed for DEBUG_SK only */
+
+#include "sshbuf.h"
+#include "ssherr.h"
+#include "digest.h"
+#define SSHKEY_INTERNAL
+#include "sshkey.h"
+
+/* ARGSUSED */
+int
+ssh_ecdsa_sk_verify(const struct sshkey *key,
+    const u_char *signature, size_t signaturelen,
+    const u_char *data, size_t datalen, u_int compat)
+{
+	ECDSA_SIG *sig = NULL;
+	BIGNUM *sig_r = NULL, *sig_s = NULL;
+	u_char sig_flags;
+	u_char msghash[32], apphash[32], sighash[32];
+	u_int sig_counter;
+	int ret = SSH_ERR_INTERNAL_ERROR;
+	struct sshbuf *b = NULL, *sigbuf = NULL, *original_signed = NULL;
+	char *ktype = NULL;
+#ifdef DEBUG_SK
+	char *tmp = NULL;
+#endif
+
+	if (key == NULL || key->ecdsa == NULL ||
+	    sshkey_type_plain(key->type) != KEY_ECDSA_SK ||
+	    signature == NULL || signaturelen == 0)
+		return SSH_ERR_INVALID_ARGUMENT;
+
+	if (key->ecdsa_nid != NID_X9_62_prime256v1)
+		return SSH_ERR_INTERNAL_ERROR;
+
+	/* fetch signature */
+	if ((b = sshbuf_from(signature, signaturelen)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
+	    sshbuf_froms(b, &sigbuf) != 0) {
+		ret = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
+		ret = SSH_ERR_KEY_TYPE_MISMATCH;
+		goto out;
+	}
+	if (sshbuf_len(b) != 0) {
+		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
+		goto out;
+	}
+
+	/* parse signature */
+	if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
+	    sshbuf_get_bignum2(sigbuf, &sig_s) != 0 ||
+	    sshbuf_get_u8(sigbuf, &sig_flags) != 0 ||
+	    sshbuf_get_u32(sigbuf, &sig_counter) != 0) {
+		ret = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	if ((sig = ECDSA_SIG_new()) == NULL) {
+		ret = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if (!ECDSA_SIG_set0(sig, sig_r, sig_s)) {
+		ret = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+#ifdef DEBUG_SK
+	fprintf(stderr, "%s: sig_r: %s\n", __func__, (tmp = BN_bn2hex(sig_r)));
+	free(tmp);
+	fprintf(stderr, "%s: sig_s: %s\n", __func__, (tmp = BN_bn2hex(sig_s)));
+	free(tmp);
+	fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
+	    __func__, sig_flags, sig_counter);
+#endif
+	sig_r = sig_s = NULL; /* transferred */
+
+	if (sshbuf_len(sigbuf) != 0) {
+		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
+		goto out;
+	}
+
+	/* Reconstruct data that was supposedly signed */
+	if ((original_signed = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((ret = ssh_digest_memory(SSH_DIGEST_SHA256, data, datalen,
+	    msghash, sizeof(msghash))) != 0)
+		goto out;
+	/* Application value is hashed before signature */
+	if ((ret = ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
+	    strlen(key->sk_application), apphash, sizeof(apphash))) != 0)
+		goto out;
+#ifdef DEBUG_SK
+	fprintf(stderr, "%s: hashed message:\n", __func__);
+	sshbuf_dump_data(msghash, sizeof(msghash), stderr);
+#endif
+	if ((ret = sshbuf_put(original_signed,
+	    apphash, sizeof(apphash))) != 0 ||
+	    (ret = sshbuf_put_u8(original_signed, sig_flags)) != 0 ||
+	    (ret = sshbuf_put_u32(original_signed, sig_counter)) != 0 ||
+	    (ret = sshbuf_put(original_signed, msghash, sizeof(msghash))) != 0)
+		goto out;
+	/* Signature is over H(original_signed) */
+	if ((ret = ssh_digest_buffer(SSH_DIGEST_SHA256, original_signed,
+	    sighash, sizeof(sighash))) != 0)
+		goto out;
+#ifdef DEBUG_SK
+	fprintf(stderr, "%s: signed buf:\n", __func__);
+	sshbuf_dump(original_signed, stderr);
+	fprintf(stderr, "%s: signed hash:\n", __func__);
+	sshbuf_dump_data(sighash, sizeof(sighash), stderr);
+#endif
+
+	/* Verify it */
+	switch (ECDSA_do_verify(sighash, sizeof(sighash), sig, key->ecdsa)) {
+	case 1:
+		ret = 0;
+		break;
+	case 0:
+		ret = SSH_ERR_SIGNATURE_INVALID;
+		goto out;
+	default:
+		ret = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+
+ out:
+	explicit_bzero(&sig_flags, sizeof(sig_flags));
+	explicit_bzero(&sig_counter, sizeof(sig_counter));
+	explicit_bzero(msghash, sizeof(msghash));
+	explicit_bzero(sighash, sizeof(msghash));
+	explicit_bzero(apphash, sizeof(apphash));
+	sshbuf_free(original_signed);
+	sshbuf_free(sigbuf);
+	sshbuf_free(b);
+	ECDSA_SIG_free(sig);
+	BN_clear_free(sig_r);
+	BN_clear_free(sig_s);
+	free(ktype);
+	return ret;
+}
diff --git a/sshkey.c b/sshkey.c
index ef90563b..d87fee8e 100644
--- a/sshkey.c
+++ b/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.84 2019/10/09 00:04:42 djm Exp $ */
+/* $OpenBSD: sshkey.c,v 1.85 2019/10/31 21:15:14 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -125,6 +125,8 @@ static const struct keytype keytypes[] = {
 	{ "ecdsa-sha2-nistp521", "ECDSA", NULL,
 	    KEY_ECDSA, NID_secp521r1, 0, 0 },
 #  endif /* OPENSSL_HAS_NISTP521 */
+	{ "sk-ecdsa-sha2-nistp256@openssh.com", "ECDSA-SK", NULL,
+	    KEY_ECDSA_SK, NID_X9_62_prime256v1, 0, 0 },
 # endif /* OPENSSL_HAS_ECC */
 	{ "ssh-rsa-cert-v01@openssh.com", "RSA-CERT", NULL,
 	    KEY_RSA_CERT, 0, 1, 0 },
@@ -143,6 +145,8 @@ static const struct keytype keytypes[] = {
 	{ "ecdsa-sha2-nistp521-cert-v01@openssh.com", "ECDSA-CERT", NULL,
 	   KEY_ECDSA_CERT, NID_secp521r1, 1, 0 },
 #  endif /* OPENSSL_HAS_NISTP521 */
+	{ "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com", "ECDSA-SK-CERT", NULL,
+	    KEY_ECDSA_SK_CERT, NID_X9_62_prime256v1, 1, 0 },
 # endif /* OPENSSL_HAS_ECC */
 #endif /* WITH_OPENSSL */
 	{ NULL, NULL, NULL, -1, -1, 0, 0 }
@@ -211,13 +215,26 @@ sshkey_type_from_name(const char *name)
 	return KEY_UNSPEC;
 }
 
+static int
+key_type_is_ecdsa_variant(int type)
+{
+	switch (type) {
+	case KEY_ECDSA:
+	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK:
+	case KEY_ECDSA_SK_CERT:
+		return 1;
+	}
+	return 0;
+}
+
 int
 sshkey_ecdsa_nid_from_name(const char *name)
 {
 	const struct keytype *kt;
 
 	for (kt = keytypes; kt->type != -1; kt++) {
-		if (kt->type != KEY_ECDSA && kt->type != KEY_ECDSA_CERT)
+		if (!key_type_is_ecdsa_variant(kt->type))
 			continue;
 		if (kt->name != NULL && strcmp(name, kt->name) == 0)
 			return kt->nid;
@@ -313,6 +330,8 @@ sshkey_size(const struct sshkey *k)
 		return BN_num_bits(dsa_p);
 	case KEY_ECDSA:
 	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK:
+	case KEY_ECDSA_SK_CERT:
 		return sshkey_curve_nid_to_bits(k->ecdsa_nid);
 #endif /* WITH_OPENSSL */
 	case KEY_ED25519:
@@ -331,6 +350,7 @@ sshkey_type_is_valid_ca(int type)
 	case KEY_RSA:
 	case KEY_DSA:
 	case KEY_ECDSA:
+	case KEY_ECDSA_SK:
 	case KEY_ED25519:
 	case KEY_XMSS:
 		return 1;
@@ -358,6 +378,8 @@ sshkey_type_plain(int type)
 		return KEY_DSA;
 	case KEY_ECDSA_CERT:
 		return KEY_ECDSA;
+	case KEY_ECDSA_SK_CERT:
+		return KEY_ECDSA_SK;
 	case KEY_ED25519_CERT:
 		return KEY_ED25519;
 	case KEY_XMSS_CERT:
@@ -533,6 +555,8 @@ sshkey_new(int type)
 		break;
 	case KEY_ECDSA:
 	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK:
+	case KEY_ECDSA_SK_CERT:
 		/* Cannot do anything until we know the group */
 		break;
 #endif /* WITH_OPENSSL */
@@ -577,6 +601,12 @@ sshkey_free(struct sshkey *k)
 		k->dsa = NULL;
 		break;
 # ifdef OPENSSL_HAS_ECC
+	case KEY_ECDSA_SK:
+	case KEY_ECDSA_SK_CERT:
+		free(k->sk_application);
+		sshbuf_free(k->sk_key_handle);
+		sshbuf_free(k->sk_reserved);
+		/* FALLTHROUGH */
 	case KEY_ECDSA:
 	case KEY_ECDSA_CERT:
 		EC_KEY_free(k->ecdsa);
@@ -676,6 +706,13 @@ sshkey_equal_public(const struct sshkey *a, const struct sshkey *b)
 		    BN_cmp(dsa_g_a, dsa_g_b) == 0 &&
 		    BN_cmp(dsa_pub_key_a, dsa_pub_key_b) == 0;
 # ifdef OPENSSL_HAS_ECC
+	case KEY_ECDSA_SK:
+	case KEY_ECDSA_SK_CERT:
+		if (a->sk_application == NULL || b->sk_application == NULL)
+			return 0;
+		if (strcmp(a->sk_application, b->sk_application) != 0)
+			return 0;
+		/* FALLTHROUGH */
 	case KEY_ECDSA_CERT:
 	case KEY_ECDSA:
 		if (a->ecdsa == NULL || b->ecdsa == NULL ||
@@ -751,6 +788,7 @@ to_blob_buf(const struct sshkey *key, struct sshbuf *b, int force_plain,
 #ifdef WITH_OPENSSL
 	case KEY_DSA_CERT:
 	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK_CERT:
 	case KEY_RSA_CERT:
 #endif /* WITH_OPENSSL */
 	case KEY_ED25519_CERT:
@@ -777,6 +815,7 @@ to_blob_buf(const struct sshkey *key, struct sshbuf *b, int force_plain,
 		break;
 # ifdef OPENSSL_HAS_ECC
 	case KEY_ECDSA:
+	case KEY_ECDSA_SK:
 		if (key->ecdsa == NULL)
 			return SSH_ERR_INVALID_ARGUMENT;
 		if ((ret = sshbuf_put_cstring(b, typename)) != 0 ||
@@ -784,6 +823,11 @@ to_blob_buf(const struct sshkey *key, struct sshbuf *b, int force_plain,
 		    sshkey_curve_nid_to_name(key->ecdsa_nid))) != 0 ||
 		    (ret = sshbuf_put_eckey(b, key->ecdsa)) != 0)
 			return ret;
+		if (type == KEY_ECDSA_SK) {
+			if ((ret = sshbuf_put_cstring(b,
+			    key->sk_application)) != 0)
+				return ret;
+		}
 		break;
 # endif
 	case KEY_RSA:
@@ -1217,7 +1261,7 @@ peek_type_nid(const char *s, size_t l, int *nid)
 			continue;
 		if (memcmp(s, kt->name, l) == 0) {
 			*nid = -1;
-			if (kt->type == KEY_ECDSA || kt->type == KEY_ECDSA_CERT)
+			if (key_type_is_ecdsa_variant(kt->type))
 				*nid = kt->nid;
 			return kt->type;
 		}
@@ -1243,9 +1287,11 @@ sshkey_read(struct sshkey *ret, char **cpp)
 	case KEY_RSA:
 	case KEY_DSA:
 	case KEY_ECDSA:
+	case KEY_ECDSA_SK:
 	case KEY_ED25519:
 	case KEY_DSA_CERT:
 	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK_CERT:
 	case KEY_RSA_CERT:
 	case KEY_ED25519_CERT:
 #ifdef WITH_XMSS
@@ -1302,7 +1348,7 @@ sshkey_read(struct sshkey *ret, char **cpp)
 		sshkey_free(k);
 		return SSH_ERR_KEY_TYPE_MISMATCH;
 	}
-	if (sshkey_type_plain(type) == KEY_ECDSA && curve_nid != k->ecdsa_nid) {
+	if (key_type_is_ecdsa_variant(type) && curve_nid != k->ecdsa_nid) {
 		sshkey_free(k);
 		return SSH_ERR_EC_CURVE_MISMATCH;
 	}
@@ -1348,6 +1394,19 @@ sshkey_read(struct sshkey *ret, char **cpp)
 		sshkey_dump_ec_key(ret->ecdsa);
 #endif
 		break;
+	case KEY_ECDSA_SK:
+		EC_KEY_free(ret->ecdsa);
+		ret->ecdsa = k->ecdsa;
+		ret->ecdsa_nid = k->ecdsa_nid;
+		ret->sk_application = k->sk_application;
+		k->ecdsa = NULL;
+		k->ecdsa_nid = -1;
+		k->sk_application = NULL;
+#ifdef DEBUG_PK
+		sshkey_dump_ec_key(ret->ecdsa);
+		fprintf(stderr, "App: %s\n", ret->sk_application);
+#endif
+		break;
 # endif /* OPENSSL_HAS_ECC */
 #endif /* WITH_OPENSSL */
 	case KEY_ED25519:
@@ -1747,15 +1806,14 @@ sshkey_from_private(const struct sshkey *k, struct sshkey **pkp)
 #endif /* WITH_OPENSSL */
 
 	*pkp = NULL;
+	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:
-		if ((n = sshkey_new(k->type)) == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
-
 		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 ||
@@ -1780,10 +1838,8 @@ sshkey_from_private(const struct sshkey *k, struct sshkey **pkp)
 # ifdef OPENSSL_HAS_ECC
 	case KEY_ECDSA:
 	case KEY_ECDSA_CERT:
-		if ((n = sshkey_new(k->type)) == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
+	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) {
@@ -1795,14 +1851,15 @@ sshkey_from_private(const struct sshkey *k, struct sshkey **pkp)
 			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;
 # endif /* OPENSSL_HAS_ECC */
 	case KEY_RSA:
 	case KEY_RSA_CERT:
-		if ((n = sshkey_new(k->type)) == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
 		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) {
@@ -1818,10 +1875,6 @@ sshkey_from_private(const struct sshkey *k, struct sshkey **pkp)
 #endif /* WITH_OPENSSL */
 	case KEY_ED25519:
 	case KEY_ED25519_CERT:
-		if ((n = sshkey_new(k->type)) == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
 		if (k->ed25519_pk != NULL) {
 			if ((n->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) {
 				r = SSH_ERR_ALLOC_FAIL;
@@ -1833,10 +1886,6 @@ sshkey_from_private(const struct sshkey *k, struct sshkey **pkp)
 #ifdef WITH_XMSS
 	case KEY_XMSS:
 	case KEY_XMSS_CERT:
-		if ((n = sshkey_new(k->type)) == NULL) {
-			r = SSH_ERR_ALLOC_FAIL;
-			goto out;
-		}
 		if ((r = sshkey_xmss_init(n, k->xmss_name)) != 0)
 			goto out;
 		if (k->xmss_pk != NULL) {
@@ -2329,6 +2378,7 @@ sshkey_from_blob_internal(struct sshbuf *b, struct sshkey **keyp,
 #endif
 		break;
 	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK_CERT:
 		/* Skip nonce */
 		if (sshbuf_get_string_direct(b, NULL, NULL) != 0) {
 			ret = SSH_ERR_INVALID_FORMAT;
@@ -2337,6 +2387,7 @@ sshkey_from_blob_internal(struct sshbuf *b, struct sshkey **keyp,
 		/* FALLTHROUGH */
 # ifdef OPENSSL_HAS_ECC
 	case KEY_ECDSA:
+	case KEY_ECDSA_SK:
 		if ((key = sshkey_new(type)) == NULL) {
 			ret = SSH_ERR_ALLOC_FAIL;
 			goto out;
@@ -2377,6 +2428,17 @@ sshkey_from_blob_internal(struct sshbuf *b, struct sshkey **keyp,
 #ifdef DEBUG_PK
 		sshkey_dump_ec_point(EC_KEY_get0_group(key->ecdsa), q);
 #endif
+		if (type == KEY_ECDSA_SK || type == KEY_ECDSA_SK_CERT) {
+			/* Parse additional security-key application string */
+			if (sshbuf_get_cstring(b, &key->sk_application,
+			    NULL) != 0) {
+				ret = SSH_ERR_INVALID_FORMAT;
+				goto out;
+			}
+#ifdef DEBUG_PK
+			fprintf(stderr, "App: %s\n", key->sk_application);
+#endif
+		}
 		break;
 # endif /* OPENSSL_HAS_ECC */
 #endif /* WITH_OPENSSL */
@@ -2665,6 +2727,10 @@ sshkey_verify(const struct sshkey *key,
 	case KEY_ECDSA_CERT:
 	case KEY_ECDSA:
 		return ssh_ecdsa_verify(key, sig, siglen, data, dlen, compat);
+	case KEY_ECDSA_SK_CERT:
+	case KEY_ECDSA_SK:
+		return ssh_ecdsa_sk_verify(key, sig, siglen, data, dlen,
+		    compat);
 # endif /* OPENSSL_HAS_ECC */
 	case KEY_RSA_CERT:
 	case KEY_RSA:
@@ -2700,6 +2766,9 @@ sshkey_to_certified(struct sshkey *k)
 	case KEY_ECDSA:
 		newtype = KEY_ECDSA_CERT;
 		break;
+	case KEY_ECDSA_SK:
+		newtype = KEY_ECDSA_SK_CERT;
+		break;
 #endif /* WITH_OPENSSL */
 	case KEY_ED25519:
 		newtype = KEY_ED25519_CERT;
@@ -2797,12 +2866,18 @@ sshkey_certify_custom(struct sshkey *k, struct sshkey *ca, const char *alg,
 		break;
 # ifdef OPENSSL_HAS_ECC
 	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK_CERT:
 		if ((ret = sshbuf_put_cstring(cert,
 		    sshkey_curve_nid_to_name(k->ecdsa_nid))) != 0 ||
 		    (ret = sshbuf_put_ec(cert,
 		    EC_KEY_get0_public_key(k->ecdsa),
 		    EC_KEY_get0_group(k->ecdsa))) != 0)
 			goto out;
+		if (k->type == KEY_ECDSA_SK_CERT) {
+			if ((ret = sshbuf_put_cstring(cert,
+			    k->sk_application)) != 0)
+				goto out;
+		}
 		break;
 # endif /* OPENSSL_HAS_ECC */
 	case KEY_RSA_CERT:
@@ -3082,6 +3157,28 @@ sshkey_private_serialize_opt(struct sshkey *key, struct sshbuf *buf,
 		    EC_KEY_get0_private_key(key->ecdsa))) != 0)
 			goto out;
 		break;
+	case KEY_ECDSA_SK:
+		if ((r = sshbuf_put_cstring(b,
+		    sshkey_curve_nid_to_name(key->ecdsa_nid))) != 0 ||
+		    (r = sshbuf_put_eckey(b, key->ecdsa)) != 0 ||
+		    (r = sshbuf_put_cstring(b, key->sk_application)) != 0 ||
+		    (r = sshbuf_put_u8(b, key->sk_flags)) != 0 ||
+		    (r = sshbuf_put_stringb(b, key->sk_key_handle)) != 0 ||
+		    (r = sshbuf_put_stringb(b, key->sk_reserved)) != 0)
+			goto out;
+		break;
+	case KEY_ECDSA_SK_CERT:
+		if (key->cert == NULL || sshbuf_len(key->cert->certblob) == 0) {
+			r = SSH_ERR_INVALID_ARGUMENT;
+			goto out;
+		}
+		if ((r = sshbuf_put_stringb(b, key->cert->certblob)) != 0 ||
+		    (r = sshbuf_put_cstring(b, key->sk_application)) != 0 ||
+		    (r = sshbuf_put_u8(b, key->sk_flags)) != 0 ||
+		    (r = sshbuf_put_stringb(b, key->sk_key_handle)) != 0 ||
+		    (r = sshbuf_put_stringb(b, key->sk_reserved)) != 0)
+			goto out;
+		break;
 # endif /* OPENSSL_HAS_ECC */
 #endif /* WITH_OPENSSL */
 	case KEY_ED25519:
@@ -3270,6 +3367,60 @@ sshkey_private_deserialize(struct sshbuf *buf, struct sshkey **kp)
 		    (r = sshkey_ec_validate_private(k->ecdsa)) != 0)
 			goto out;
 		break;
+	case KEY_ECDSA_SK:
+		if ((k = sshkey_new(type)) == NULL) {
+			r = SSH_ERR_ALLOC_FAIL;
+			goto out;
+		}
+		if ((k->ecdsa_nid = sshkey_ecdsa_nid_from_name(tname)) == -1) {
+			r = SSH_ERR_INVALID_ARGUMENT;
+			goto out;
+		}
+		if ((r = sshbuf_get_cstring(buf, &curve, NULL)) != 0)
+			goto out;
+		if (k->ecdsa_nid != sshkey_curve_name_to_nid(curve)) {
+			r = SSH_ERR_EC_CURVE_MISMATCH;
+			goto out;
+		}
+		if ((k->sk_key_handle = sshbuf_new()) == NULL ||
+		    (k->sk_reserved = sshbuf_new()) == NULL) {
+			r = SSH_ERR_ALLOC_FAIL;
+			goto out;
+		}
+		k->ecdsa = EC_KEY_new_by_curve_name(k->ecdsa_nid);
+		if (k->ecdsa  == NULL) {
+			r = SSH_ERR_LIBCRYPTO_ERROR;
+			goto out;
+		}
+		if ((r = sshbuf_get_eckey(buf, k->ecdsa)) != 0 ||
+		    (r = sshbuf_get_cstring(buf, &k->sk_application,
+		    NULL)) != 0 ||
+		    (r = sshbuf_get_u8(buf, &k->sk_flags)) != 0 ||
+		    (r = sshbuf_get_stringb(buf, k->sk_key_handle)) != 0 ||
+		    (r = sshbuf_get_stringb(buf, k->sk_reserved)) != 0)
+			goto out;
+		if ((r = sshkey_ec_validate_public(EC_KEY_get0_group(k->ecdsa),
+		    EC_KEY_get0_public_key(k->ecdsa))) != 0)
+			goto out;
+		break;
+	case KEY_ECDSA_SK_CERT:
+		if ((r = sshkey_froms(buf, &k)) != 0)
+			goto out;
+		if ((k->sk_key_handle = sshbuf_new()) == NULL ||
+		    (k->sk_reserved = sshbuf_new()) == NULL) {
+			r = SSH_ERR_ALLOC_FAIL;
+			goto out;
+		}
+		if ((r = sshbuf_get_cstring(buf, &k->sk_application,
+		    NULL)) != 0 ||
+		    (r = sshbuf_get_u8(buf, &k->sk_flags)) != 0 ||
+		    (r = sshbuf_get_stringb(buf, k->sk_key_handle)) != 0 ||
+		    (r = sshbuf_get_stringb(buf, k->sk_reserved)) != 0)
+			goto out;
+		if ((r = sshkey_ec_validate_public(EC_KEY_get0_group(k->ecdsa),
+		    EC_KEY_get0_public_key(k->ecdsa))) != 0)
+			goto out;
+		break;
 # endif /* OPENSSL_HAS_ECC */
 	case KEY_RSA:
 		if ((k = sshkey_new(type)) == NULL) {
@@ -4090,6 +4241,9 @@ sshkey_private_to_fileblob(struct sshkey *key, struct sshbuf *blob,
 #ifdef WITH_XMSS
 	case KEY_XMSS:
 #endif /* WITH_XMSS */
+#ifdef WITH_OPENSSL
+	case KEY_ECDSA_SK:
+#endif /* WITH_OPENSSL */
 		return sshkey_private_to_blob2(key, blob, passphrase,
 		    comment, openssh_format_cipher, openssh_format_rounds);
 	default:
@@ -4111,7 +4265,6 @@ sshkey_private_to_fileblob(struct sshkey *key, struct sshbuf *blob,
 #endif /* WITH_OPENSSL */
 }
 
-
 #ifdef WITH_OPENSSL
 static int
 translate_libcrypto_error(unsigned long pem_err)
diff --git a/sshkey.h b/sshkey.h
index 1119a7b0..2edcb13a 100644
--- a/sshkey.h
+++ b/sshkey.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.h,v 1.34 2019/09/03 08:31:20 djm Exp $ */
+/* $OpenBSD: sshkey.h,v 1.35 2019/10/31 21:15:14 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -65,6 +65,8 @@ enum sshkey_types {
 	KEY_ED25519_CERT,
 	KEY_XMSS,
 	KEY_XMSS_CERT,
+	KEY_ECDSA_SK,
+	KEY_ECDSA_SK_CERT,
 	KEY_UNSPEC
 };
 
@@ -118,18 +120,30 @@ struct sshkey_cert {
 struct sshkey {
 	int	 type;
 	int	 flags;
+	/* KEY_RSA */
 	RSA	*rsa;
+	/* KEY_DSA */
 	DSA	*dsa;
+	/* KEY_ECDSA and KEY_ECDSA_SK */
 	int	 ecdsa_nid;	/* NID of curve */
 	EC_KEY	*ecdsa;
+	/* KEY_ED25519 */
 	u_char	*ed25519_sk;
 	u_char	*ed25519_pk;
+	/* KEY_XMSS */
 	char	*xmss_name;
 	char	*xmss_filename;	/* for state file updates */
 	void	*xmss_state;	/* depends on xmss_name, opaque */
 	u_char	*xmss_sk;
 	u_char	*xmss_pk;
+	/* KEY_ECDSA_SK */
+	char	*sk_application;
+	uint8_t	sk_flags;
+	struct sshbuf *sk_key_handle;
+	struct sshbuf *sk_reserved;
+	/* Certificates */
 	struct sshkey_cert *cert;
+	/* Private key shielding */
 	u_char	*shielded_private;
 	size_t	shielded_len;
 	u_char	*shield_prekey;
@@ -268,6 +282,9 @@ int ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
 int ssh_ecdsa_verify(const struct sshkey *key,
     const u_char *signature, size_t signaturelen,
     const u_char *data, size_t datalen, u_int compat);
+int ssh_ecdsa_sk_verify(const struct sshkey *key,
+    const u_char *signature, size_t signaturelen,
+    const u_char *data, size_t datalen, u_int compat);
 int ssh_ed25519_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat);
 int ssh_ed25519_verify(const struct sshkey *key,