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]>

#include "tommath_private.h"
#ifdef BN_MP_CLEAR_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* clear one (frees)  */
void mp_clear(mp_int *a)
{
   /* only do anything if a hasn't been freed previously */
   if (a->dp != NULL) {
      /* free ram */
      MP_FREE_DIGITS(a->dp, a->alloc);

      /* reset members to make debugging easier */
      a->dp    = NULL;
      a->alloc = a->used = 0;
      a->sign  = MP_ZPOS;
   }
}
#endif