pki: Query private key for supported signature schemes

src/pki/commands/acert.c

@@ -228,6 +228,11 @@ static int acert()
 		goto end;
 	}
 	scheme = get_signature_scheme(private, digest, pss);
+	if (!scheme)
+	{
+		error = "no signature scheme found";
+		goto end;
+	}
 
 	ac = lib->creds->create(lib->creds,
 							CRED_CERTIFICATE, CERT_X509_AC,

src/pki/commands/issue.c

@@ -536,6 +536,11 @@ static int issue()
 										chunk_from_chars(ASN1_SEQUENCE, 0));
 	}
 	scheme = get_signature_scheme(private, digest, pss);
+	if (!scheme)
+	{
+		error = "no signature scheme found";
+		goto end;
+	}
 
 	cert = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509,
 					BUILD_SIGNING_KEY, private, BUILD_SIGNING_CERT, ca,

src/pki/commands/req.c

@@ -168,6 +168,11 @@ static int req()
 		goto end;
 	}
 	scheme = get_signature_scheme(private, digest, pss);
+	if (!scheme)
+	{
+		error = "no signature scheme found";
+		goto end;
+	}
 
 	cert = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_PKCS10_REQUEST,
 							  BUILD_SIGNING_KEY, private,

src/pki/commands/self.c

@@ -378,6 +378,11 @@ static int self()
 		rng->destroy(rng);
 	}
 	scheme = get_signature_scheme(private, digest, pss);
+	if (!scheme)
+	{
+		error = "no signature scheme found";
+		goto end;
+	}
 
 	cert = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509,
 						BUILD_SIGNING_KEY, private, BUILD_PUBLIC_KEY, public,

src/pki/commands/signcrl.c

@@ -399,6 +399,12 @@ static int sign_crl()
 	chunk_increment(crl_serial);
 
 	scheme = get_signature_scheme(private, digest, pss);
+	if (!scheme)
+	{
+		error = "no signature scheme found";
+		goto error;
+	}
+
 	enumerator = enumerator_create_filter(list->create_enumerator(list),
 										  filter, NULL, NULL);
 	crl = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509_CRL,