pki: Support RSA SHA2 signatures of sessionid for server

This involves mostly creation of host keys proofs but needs
to follow the same procedure as the client authentication
signatures.

At the same time, the SHA2 extension is enabled in the pkd
so we are able to atomicaly provide correct signatures and
pass tests.

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

1 files changed, 13 insertions, 3 deletions

diff --git a/src/pki_mbedcrypto.c b/src/pki_mbedcrypto.c
index 68a80b42..fceacd80 100644
--- a/src/pki_mbedcrypto.c
+++ b/src/pki_mbedcrypto.c
@@ -1127,22 +1127,32 @@ ssh_signature pki_do_sign_hash(const ssh_key privkey,
 }
 
 #ifdef WITH_SERVER
-ssh_signature pki_do_sign_sessionid(const ssh_key key, const unsigned char
-        *hash, size_t hlen)
+ssh_signature pki_do_sign_sessionid_hash(const ssh_key key,
+                                         const unsigned char *hash,
+                                         size_t hlen,
+                                         enum ssh_digest_e hash_type)
 {
     ssh_signature sig = NULL;
     int rc;
 
+    /* Only RSA supports different signature algorithm types now */
+    if (key->type != SSH_KEYTYPE_RSA && hash_type != SSH_DIGEST_AUTO) {
+        SSH_LOG(SSH_LOG_WARN, "Incompatible signature algorithm passed");
+        return NULL;
+    }
+
     sig = ssh_signature_new();
     if (sig == NULL) {
         return NULL;
     }
+
     sig->type = key->type;
     sig->type_c = key->type_c;
 
     switch (key->type) {
         case SSH_KEYTYPE_RSA:
-            sig->rsa_sig = rsa_do_sign_hash(hash, hlen, key->rsa, SSH_DIGEST_AUTO);
+            sig->type_c = ssh_key_signature_to_char(key->type, hash_type);
+            sig->rsa_sig = rsa_do_sign_hash(hash, hlen, key->rsa, hash_type);
             if (sig->rsa_sig == NULL) {
                 ssh_signature_free(sig);
                 return NULL;