Implement server-side support for sk-ecdsa U2F-backed keys (#142) * Implement server-side support for sk-ecdsa U2F-backed keys * Fix out-of-bounds read on normal ecdsa-sha2-[identifier] keys * Fix one more potential out-of-bounds read * Check if nistp256 curve is used in sk-ecdsa-sha2- key It's the only allowed curve per PROTOCOL.u2f specification * Implement server-side support for sk-ed25519 FIDO2-backed keys * Keys with type sk-* make no sense as host keys, so they should be disabled * fix typo * Make sk-ecdsa call buf_ecdsa_verify This reduces code duplication, the SK code just handles the different message format. * Reduce sk specific code The application id can be stored in signkey, then we don't need to call sk-specific functions from svr-authpubkey * Remove debugging output, which causes compilation errors with DEBUG_TRACE disabled * Proper cleanup of sk_app Co-authored-by: Matt Johnston <[email protected]>

--- a/svr-runopts.c	Sat Jan 22 12:46:08 2022 +0800
+++ b/svr-runopts.c	Sat Jan 22 16:53:04 2022 +0300
@@ -668,6 +668,12 @@
 		any_keys = 1;
 	}
 #endif
+#if DROPBEAR_SK_ECDSA
+	disablekey(DROPBEAR_SIGNKEY_SK_ECDSA_NISTP256);
+#endif 
+#if DROPBEAR_SK_ED25519
+	disablekey(DROPBEAR_SIGNKEY_SK_ED25519);
+#endif
 
 	if (!any_keys) {
 		dropbear_exit("No hostkeys available. 'dropbear -R' may be useful or run dropbearkey.");