hostkey: implement ECDSA/RSA certificate hostkey verification

Implement server hostkey verification for the six ECDSA/RSA OpenSSH
certificate hostkey variants:

- `ecdsa-sha2-nistp256-cert-v01@openssh.com`
- `ecdsa-sha2-nistp384-cert-v01@openssh.com`
- `ecdsa-sha2-nistp521-cert-v01@openssh.com`
- `ssh-rsa-cert-v01@openssh.com`
- `rsa-sha2-256-cert-v01@openssh.com`
- `rsa-sha2-512-cert-v01@openssh.com`

This fixes #2434, where these algorithms were advertised and accepted as
preferences but had `NULL` hostkey `init`/`sig_verify` callbacks. A
certificate-only hostkey offer therefore caused
`LIBSSH2_ERROR_KEX_FAILURE (-5)`.

## Implementation

- ECDSA certificate parsing uses one shared init path for all three
  curves. It validates the certificate type, nonce, inner curve name, and
  EC point before constructing the verification context.
- RSA certificate parsing uses one shared init path for all three RSA
  signature variants.
- Per-algorithm RSA `sig_verify` callbacks remain distinct.
- Per `PROTOCOL.certkeys`, the RSA/SHA-2 certificate blob itself carries
  the type string `ssh-rsa-cert-v01@openssh.com`; the negotiated SHA-2
  algorithm is represented by KEXINIT and the exchange signature.
- Certificate CA trust validation remains out of scope, consistent with
  existing plain-hostkey handling.

## Tests

- Host CA fixtures (`keys/ca_host_ecdsa`, `keys/ca_host_rsa`) and
  CA-signed host certificates for the ECDSA P-256 and RSA host keys in the
  Docker OpenSSH fixture.
- The certificate algorithms are exercised through `test_read_algos.txt`
  and `FIXTURE_TEST_HOSTKEY`: `ecdsa-sha2-nistp256-cert-v01@openssh.com`,
  `rsa-sha2-256-cert-v01@openssh.com`,
  `rsa-sha2-512-cert-v01@openssh.com`, `ssh-rsa-cert-v01@openssh.com`,
  plus the pre-existing `ssh-ed25519-cert-v01@openssh.com`.
- The ECDSA P-384/P-521 certificate variants share the same codepath and
  are covered by it; only P-256 is tested directly to keep the fixture
  matrix lean (per maintainer review feedback).
- Disabled-backend skip entries in `tests/session_fixture.c` for the new
  certificate algorithms.
- Preserved the existing ed25519 certificate test path.

Fixes #2434
Follow-up to 6036e57720 #2513
Follow-up to 65a276e8fe #2064

Closes #2539

src/hostkey.c

@@ -354,13 +354,81 @@ static const struct hostkey_method hostkey_method_ssh_rsa_sha2_512 = {
     hostkey_method_ssh_rsa_dtor,
 };
 #endif /* LIBSSH2_RSA_SHA2 */
+
+#if LIBSSH2_RSA_SHA1 || LIBSSH2_RSA_SHA2
+/*
+ * Initialize the server hostkey cert.
+ *
+ * OpenSSH certificate format (PROTOCOL.certkeys):
+ *   string    "ssh-rsa-cert-v01@openssh.com"
+ *   string    nonce
+ *   mpint     e
+ *   mpint     n
+ *   <trailing cert metadata we do not read>
+ *
+ * The rsa-sha2-{256,512}-cert-v01 types appear only in KEXINIT and the
+ * signature, so all three cert variants share this blob layout and init.
+ * The existing per-variant sig_verify operates on the abstract (the inner
+ * RSA key ctx) and is reused verbatim.
+ */
+static int hostkey_method_ssh_rsa_init_cert(LIBSSH2_SESSION *session,
+                                            const unsigned char *hostkey_data,
+                                            size_t hostkey_data_len,
+                                            void **abstract)
+{
+    ssh2_rsa_ctx *rsa;
+    unsigned char *e, *n, *nonce;
+    size_t e_len, n_len, nonce_len;
+    struct string_buf buf;
+
+    if(*abstract) {
+        hostkey_method_ssh_rsa_dtor(session, abstract);
+        *abstract = NULL;
+    }
+
+    /* 4 + 28 + 4 + 16 + 4 + 4 */
+    if(hostkey_data_len < 60) {
+        ssh2_deb((session, LIBSSH2_TRACE_ERROR, "host key length too short"));
+        return -1;
+    }
+
+    buf.data = SSH2_UNCONST(hostkey_data);
+    buf.dataptr = buf.data;
+    buf.len = hostkey_data_len;
+
+    if(ssh2_match_string(&buf, "ssh-rsa-cert-v01@openssh.com"))
+        return -1;
+
+    /* nonce - must be min of 16 bytes */
+    if(ssh2_get_string(&buf, &nonce, &nonce_len) || nonce_len < 16)
+        return -1;
+
+    if(ssh2_get_string(&buf, &e, &e_len) ||
+       ssh2_get_string(&buf, &n, &n_len))
+        return -1;
+
+    /*
+     * we cannot check for eob here because certs
+     * have more meta data we do not read
+     */
+
+    if(ssh2_rsa_new(&rsa, session, e, e_len, n, n_len,
+                    NULL, 0, NULL, 0, NULL, 0, NULL, 0, NULL, 0, NULL, 0))
+        return -1;
+
+    *abstract = rsa;
+
+    return 0;
+}
+#endif /* LIBSSH2_RSA_SHA1 || LIBSSH2_RSA_SHA2 */
+
 #if LIBSSH2_RSA_SHA1
 static const struct hostkey_method hostkey_method_ssh_rsa_cert = {
     "ssh-rsa-cert-v01@openssh.com",
     SSH2_SHA1_DIG_LEN,
-    NULL,
+    hostkey_method_ssh_rsa_init_cert,
     hostkey_method_ssh_rsa_initPEM,
-    NULL,
+    hostkey_method_ssh_rsa_sig_verify,
     hostkey_method_ssh_rsa_signv,
     NULL, /* encrypt */
     hostkey_method_ssh_rsa_dtor,
@@ -370,9 +438,9 @@ static const struct hostkey_method hostkey_method_ssh_rsa_cert = {
 static const struct hostkey_method hostkey_method_ssh_rsa_sha2_256_cert = {
     "rsa-sha2-256-cert-v01@openssh.com",
     SSH2_SHA256_DIG_LEN,
-    NULL,
+    hostkey_method_ssh_rsa_init_cert,
     hostkey_method_ssh_rsa_initPEM,
-    NULL,
+    hostkey_method_ssh_rsa_sha2_256_sig_verify,
     hostkey_method_ssh_rsa_sha2_256_signv,
     NULL, /* encrypt */
     hostkey_method_ssh_rsa_dtor,
@@ -381,9 +449,9 @@ static const struct hostkey_method hostkey_method_ssh_rsa_sha2_256_cert = {
 static const struct hostkey_method hostkey_method_ssh_rsa_sha2_512_cert = {
     "rsa-sha2-512-cert-v01@openssh.com",
     SSH2_SHA512_DIG_LEN,
-    NULL,
+    hostkey_method_ssh_rsa_init_cert,
     hostkey_method_ssh_rsa_initPEM,
-    NULL,
+    hostkey_method_ssh_rsa_sha2_512_sig_verify,
     hostkey_method_ssh_rsa_sha2_512_signv,
     NULL, /* encrypt */
     hostkey_method_ssh_rsa_dtor,
@@ -805,12 +873,110 @@ static const struct hostkey_method hostkey_method_ecdsa_ssh_nistp521 = {
     hostkey_method_ssh_ecdsa_dtor,
 };
 
+/*
+ * Initialize the server hostkey cert.
+ *
+ * OpenSSH certificate format (PROTOCOL.certkeys):
+ *   string    "ecdsa-sha2-nistpXXX-cert-v01@openssh.com"
+ *   string    nonce
+ *   string    curve        (same as the plain key)
+ *   string    public_key   (EC point, same as the plain key)
+ *   <trailing cert metadata we do not read>
+ *
+ * The cert type string is the same as the negotiated method by definition,
+ * so we skip it and the nonce, then reuse the plain curve-name + EC point
+ * parsing. The existing sig_verify operates on the abstract (the inner
+ * key ctx) and is reused verbatim.
+ */
+static int hostkey_method_ssh_ecdsa_init_cert(
+    LIBSSH2_SESSION *session,
+    const unsigned char *hostkey_data,
+    size_t hostkey_data_len,
+    void **abstract)
+{
+    ssh2_ecdsa_ctx *ec_ctx = NULL;
+    char *domain, *type_str;
+    unsigned char *public_key, *nonce;
+    size_t key_len, domain_len, type_len, nonce_len;
+    ssh2_curve_type curve;
+    struct string_buf buf;
+
+    if(abstract && *abstract) {
+        hostkey_method_ssh_ecdsa_dtor(session, abstract);
+        *abstract = NULL;
+    }
+
+    /* Minimum size for a nistp256 certificate with a 16-byte nonce. */
+    if(hostkey_data_len < 145) {
+        ssh2_deb((session, LIBSSH2_TRACE_ERROR, "host key length too short"));
+        return -1;
+    }
+
+    buf.data = SSH2_UNCONST(hostkey_data);
+    buf.dataptr = buf.data;
+    buf.len = hostkey_data_len;
+
+    if(ssh2_get_chars(&buf, &type_str, &type_len))
+        return -1;
+
+    /* cert type string must match the negotiated hostkey method */
+    if(type_len != strlen(session->hostkey->name) ||
+       strncmp(type_str, session->hostkey->name, type_len))
+        return -1;
+
+    if(SSH2_IS_LITERAL(type_str, type_len,
+                       "ecdsa-sha2-nistp256-cert-v01@openssh.com"))
+        curve = SSH2_EC_CURVE_NISTP256;
+    else if(SSH2_IS_LITERAL(type_str, type_len,
+                            "ecdsa-sha2-nistp384-cert-v01@openssh.com"))
+        curve = SSH2_EC_CURVE_NISTP384;
+    else if(SSH2_IS_LITERAL(type_str, type_len,
+                            "ecdsa-sha2-nistp521-cert-v01@openssh.com"))
+        curve = SSH2_EC_CURVE_NISTP521;
+    else
+        return -1;
+
+    /* nonce - must be min of 16 bytes */
+    if(ssh2_get_string(&buf, &nonce, &nonce_len) || nonce_len < 16)
+        return -1;
+
+    /* inner public key: curve name */
+    if(ssh2_get_chars(&buf, &domain, &domain_len))
+        return -1;
+
+    if((curve == SSH2_EC_CURVE_NISTP256 &&
+        !SSH2_IS_LITERAL(domain, domain_len, "nistp256")) ||
+       (curve == SSH2_EC_CURVE_NISTP384 &&
+        !SSH2_IS_LITERAL(domain, domain_len, "nistp384")) ||
+       (curve == SSH2_EC_CURVE_NISTP521 &&
+        !SSH2_IS_LITERAL(domain, domain_len, "nistp521")))
+        return -1;
+
+    /* inner public key: EC point */
+    if(ssh2_get_string(&buf, &public_key, &key_len))
+        return -1;
+
+    /*
+     * we cannot check for eob here because certs
+     * have more meta data we do not read
+     */
+
+    if(ssh2_ecdsa_curve_name_with_octal_new(&ec_ctx, session, public_key,
+                                            key_len, curve))
+        return -1;
+
+    if(abstract)
+        *abstract = ec_ctx;
+
+    return 0;
+}
+
 static const struct hostkey_method hostkey_method_ecdsa_ssh_nistp256_cert = {
     "ecdsa-sha2-nistp256-cert-v01@openssh.com",
     SSH2_SHA256_DIG_LEN,
-    NULL,
+    hostkey_method_ssh_ecdsa_init_cert,
     hostkey_method_ssh_ecdsa_initPEM,
-    NULL,
+    hostkey_method_ssh_ecdsa_sig_verify,
     hostkey_method_ssh_ecdsa_signv,
     NULL, /* encrypt */
     hostkey_method_ssh_ecdsa_dtor,
@@ -819,9 +985,9 @@ static const struct hostkey_method hostkey_method_ecdsa_ssh_nistp256_cert = {
 static const struct hostkey_method hostkey_method_ecdsa_ssh_nistp384_cert = {
     "ecdsa-sha2-nistp384-cert-v01@openssh.com",
     SSH2_SHA384_DIG_LEN,
-    NULL,
+    hostkey_method_ssh_ecdsa_init_cert,
     hostkey_method_ssh_ecdsa_initPEM,
-    NULL,
+    hostkey_method_ssh_ecdsa_sig_verify,
     hostkey_method_ssh_ecdsa_signv,
     NULL, /* encrypt */
     hostkey_method_ssh_ecdsa_dtor,
@@ -830,9 +996,9 @@ static const struct hostkey_method hostkey_method_ecdsa_ssh_nistp384_cert = {
 static const struct hostkey_method hostkey_method_ecdsa_ssh_nistp521_cert = {
     "ecdsa-sha2-nistp521-cert-v01@openssh.com",
     SSH2_SHA512_DIG_LEN,
-    NULL,
+    hostkey_method_ssh_ecdsa_init_cert,
     hostkey_method_ssh_ecdsa_initPEM,
-    NULL,
+    hostkey_method_ssh_ecdsa_sig_verify,
     hostkey_method_ssh_ecdsa_signv,
     NULL, /* encrypt */
     hostkey_method_ssh_ecdsa_dtor,

tests/Makefile.inc

@@ -73,8 +73,12 @@ EXTRA_DIST = \
   .checksrc \
   CMakeLists.txt \
   keys-generate.sh \
+  keys/ca_host_ecdsa \
+  keys/ca_host_ecdsa.pub \
   keys/ca_host_ed25519 \
   keys/ca_host_ed25519.pub \
+  keys/ca_host_rsa \
+  keys/ca_host_rsa.pub \
   keys/ca_user_ecdsa \
   keys/ca_user_ecdsa.pub \
   keys/ca_user_ed25519 \
@@ -133,11 +137,13 @@ EXTRA_DIST = \
   openssh_server/authorized_keys \
   openssh_server/ca_user_keys.pub \
   openssh_server/ssh_host_ecdsa_key \
+  openssh_server/ssh_host_ecdsa_key-cert.pub \
   openssh_server/ssh_host_ecdsa_key.pub \
   openssh_server/ssh_host_ed25519_key \
   openssh_server/ssh_host_ed25519_key-cert.pub \
   openssh_server/ssh_host_ed25519_key.pub \
   openssh_server/ssh_host_rsa_key \
+  openssh_server/ssh_host_rsa_key-cert.pub \
   openssh_server/ssh_host_rsa_key.pub \
   openssh_server/sshd_config \
   test_read_algos.test \

tests/keys-generate.sh

@@ -24,6 +24,8 @@ rm -f keys/ca_*
 rm -f keys/id_*
 
 # host CAs
+ssh-keygen -t rsa     -b 2048 -N ''          -m RFC4716 -C 'ca_host_rsa'                  -f 'keys/ca_host_rsa'
+ssh-keygen -t ecdsa   -b  256 -N ''          -m RFC4716 -C 'ca_host_ecdsa'                -f 'keys/ca_host_ecdsa'
 ssh-keygen -t ed25519         -N ''          -m RFC4716 -C 'ca_host_ed25519'              -f 'keys/ca_host_ed25519'
 
 # user CAs
@@ -36,6 +38,8 @@ id='identity'
 pr="${1:-libssh2}"
 
 # host certificates
+ssh-keygen                 -h -I 'host_rsa'     -n "${pr}" -s 'keys/ca_host_rsa'             'openssh_server/ssh_host_rsa_key.pub'
+ssh-keygen                 -h -I 'host_ecdsa'   -n "${pr}" -s 'keys/ca_host_ecdsa'           'openssh_server/ssh_host_ecdsa_key.pub'
 ssh-keygen                 -h -I 'host_ed25519' -n "${pr}" -s 'keys/ca_host_ed25519'         'openssh_server/ssh_host_ed25519_key.pub'
 
 # inspect PKCS8 private keys with command:

tests/keys/ca_host_ecdsa

@@ -0,0 +1,9 @@
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAaAAAABNlY2RzYS
+1zaGEyLW5pc3RwMjU2AAAACG5pc3RwMjU2AAAAQQQlZVqXG/s2cxstuRu2VD1UY9jkl44i
+Cex0v1/uHAkZUKxVnrtkB+R9emZKOYRub8SD1dzucgg7+H134IacQsjpAAAAqF8h1hBfId
+YQAAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBCVlWpcb+zZzGy25
+G7ZUPVRj2OSXjiIJ7HS/X+4cCRlQrFWeu2QH5H16Zko5hG5vxIPV3O5yCDv4fXfghpxCyO
+kAAAAgGCFyUNcWR6/7aB+j/Yiq21Lb8NH5k/T/gjKx0LzfO1cAAAANY2FfaG9zdF9lY2Rz
+YQECAw==
+-----END OPENSSH PRIVATE KEY-----

tests/keys/ca_host_ecdsa.pub

@@ -0,0 +1 @@
+ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBCVlWpcb+zZzGy25G7ZUPVRj2OSXjiIJ7HS/X+4cCRlQrFWeu2QH5H16Zko5hG5vxIPV3O5yCDv4fXfghpxCyOk= ca_host_ecdsa

tests/keys/ca_host_rsa

@@ -0,0 +1,27 @@
+-----BEGIN OPENSSH PRIVATE KEY-----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+-----END OPENSSH PRIVATE KEY-----

tests/keys/ca_host_rsa.pub

@@ -0,0 +1 @@
+ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDQ+NILuxzrg1o5ocePyBghxMgApq+MKj714QBN6NuRPEIrtC4rJOuTxPj7BmxqodoYJyLlIH7hixUdt7QuYOSLMKHwp/W56uCj8wVdWfiFLvZyi2/14n/4SrLWIncFyJIgOq2JLkzEZ3x2D4vvz2NeatopPlQq82ONvNnwxT+bfgQaWqANXnXKUNAjv2L4BALdh/BP8puIAtrVqcOrOa7cD+pW2rHbKZu1rnXfUjExm02ALCnHrjkyIiz+eXgJFMSRX9LiynBMvHaeNZJ0RsDoys+rINUZHBk662q+ezu5ggOHN5Pho+z4Uk11HnOmpHqR47f/TDJN4MkV6HMm1YPp ca_host_rsa

tests/openssh_server/Dockerfile

@@ -27,6 +27,12 @@ COPY ssh_host_ed25519_key /tmp/etc/ssh/ssh_host_ed25519_key
 RUN install -m 0600 /tmp/etc/ssh/ssh_host_ed25519_key /etc/ssh/ssh_host_ed25519_key
 
 # Host certificates
+COPY ssh_host_rsa_key-cert.pub /tmp/etc/ssh/ssh_host_rsa_key-cert.pub
+RUN install -m 0644 /tmp/etc/ssh/ssh_host_rsa_key-cert.pub /etc/ssh/ssh_host_rsa_key-cert.pub
+
+COPY ssh_host_ecdsa_key-cert.pub /tmp/etc/ssh/ssh_host_ecdsa_key-cert.pub
+RUN install -m 0644 /tmp/etc/ssh/ssh_host_ecdsa_key-cert.pub /etc/ssh/ssh_host_ecdsa_key-cert.pub
+
 COPY ssh_host_ed25519_key-cert.pub /tmp/etc/ssh/ssh_host_ed25519_key-cert.pub
 RUN install -m 0644 /tmp/etc/ssh/ssh_host_ed25519_key-cert.pub /etc/ssh/ssh_host_ed25519_key-cert.pub
 
@@ -43,6 +49,8 @@ RUN sed -i 's/KbdInteractiveAuthentication no/KbdInteractiveAuthentication yes/'
 COPY sshd_config /tmp/etc/ssh/sshd_config
 RUN cat /tmp/etc/ssh/sshd_config >> /etc/ssh/sshd_config
 RUN echo 'TrustedUserCAKeys /etc/ssh/ca_user_keys.pub' >> /etc/ssh/sshd_config
+RUN echo 'HostCertificate /etc/ssh/ssh_host_rsa_key-cert.pub' >> /etc/ssh/sshd_config
+RUN echo 'HostCertificate /etc/ssh/ssh_host_ecdsa_key-cert.pub' >> /etc/ssh/sshd_config
 RUN echo 'HostCertificate /etc/ssh/ssh_host_ed25519_key-cert.pub' >> /etc/ssh/sshd_config
 
 # SSH login fix. Otherwise user is kicked off after login

tests/openssh_server/ssh_host_ecdsa_key-cert.pub

@@ -0,0 +1 @@
+ecdsa-sha2-nistp256-cert-v01@openssh.com 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 openssh_server/ssh_host_ecdsa_key.pub

tests/openssh_server/ssh_host_rsa_key-cert.pub

@@ -0,0 +1 @@
+ssh-rsa-cert-v01@openssh.com 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 openssh_server/ssh_host_rsa_key.pub

tests/openssh_server/sshd_config

@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
 CASignatureAlgorithms +ssh-rsa
-HostKeyAlgorithms +ssh-rsa
+HostKeyAlgorithms +ssh-rsa,ssh-rsa-cert-v01@openssh.com
 # modern name in OpenSSH 8.5+: PubkeyAcceptedAlgorithms
 PubkeyAcceptedKeyTypes +ssh-rsa,ssh-rsa-cert-v01@openssh.com
 MACs +hmac-sha1,hmac-sha1-96,hmac-sha2-256,hmac-sha2-512,hmac-md5,hmac-md5-96,umac-64@openssh.com,umac-128@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-md5-etm@openssh.com,hmac-md5-96-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com

tests/session_fixture.c

@@ -99,6 +99,16 @@ static char const *skip_mac[] = {
 
 /* List of HOSTKEY algorithms for which tests are skipped */
 static char const *skip_hostkey[] = {
+#if !LIBSSH2_ECDSA
+    "ecdsa-sha2-nistp256-cert-v01@openssh.com",
+#endif
+#if !LIBSSH2_RSA_SHA2
+    "rsa-sha2-256-cert-v01@openssh.com",
+    "rsa-sha2-512-cert-v01@openssh.com",
+#endif
+#if !LIBSSH2_RSA_SHA1
+    "ssh-rsa-cert-v01@openssh.com",
+#endif
 #if !LIBSSH2_ED25519
     "ssh-ed25519-cert-v01@openssh.com",
 #endif

tests/test_read_algos.txt

@@ -17,4 +17,8 @@ hmac-sha2-256
 hmac-sha2-256-etm@openssh.com
 hmac-sha2-512
 hmac-sha2-512-etm@openssh.com
+ecdsa-sha2-nistp256-cert-v01@openssh.com
+rsa-sha2-256-cert-v01@openssh.com
+rsa-sha2-512-cert-v01@openssh.com
 ssh-ed25519-cert-v01@openssh.com
+ssh-rsa-cert-v01@openssh.com