#include "includes.h"

#if DROPBEAR_SK_ECDSA

#include "dbutil.h"

#include "ecc.h"

#include "ecdsa.h"

#include "sk-ecdsa.h"

#include "ssh.h"

int buf_sk_ecdsa_verify(buffer *buf, const ecc_key *key, const buffer *data_buf,

      const char* app, unsigned int applen,

      unsigned char sk_flags_mask) {

  hash_state hs;

  unsigned char subhash[SHA256_HASH_SIZE];

  buffer *sk_buffer = NULL, *sig_buffer = NULL;

  unsigned char flags;

  unsigned int counter;

  int ret;

  TRACE(("buf_sk_ecdsa_verify"))

  /* from https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.u2f */

  /* ecdsa signature to verify (r, s) */

  sig_buffer = buf_getbuf(buf);

  flags = buf_getbyte (buf);

  counter = buf_getint (buf);

  /* create the message to be signed */

  sk_buffer = buf_new (2*SHA256_HASH_SIZE+5);

  sha256_init (&hs);

  sha256_process (&hs, app, applen);

  sha256_done (&hs, subhash);

  buf_putbytes (sk_buffer, subhash, sizeof (subhash));

  buf_putbyte (sk_buffer, flags);

  buf_putint (sk_buffer, counter);

  sha256_init (&hs);

  sha256_process (&hs, data_buf->data, data_buf->len);

  sha256_done (&hs, subhash);

  buf_putbytes (sk_buffer, subhash, sizeof (subhash));

  ret = buf_ecdsa_verify(sig_buffer, key, sk_buffer);

  buf_free(sk_buffer);

  buf_free(sig_buffer);

  if (~flags & sk_flags_mask & SSH_SK_USER_PRESENCE_REQD) {

    if (ret == DROPBEAR_SUCCESS) {

      dropbear_log(LOG_WARNING, "Rejecting, user-presence not set");

    }

    ret = DROPBEAR_FAILURE;

  }

  if (~flags & sk_flags_mask & SSH_SK_USER_VERIFICATION_REQD) {

    if (ret == DROPBEAR_SUCCESS) {

      dropbear_log(LOG_WARNING, "Rejecting, user-verification not set");

    }

    ret = DROPBEAR_FAILURE;

  }

  TRACE(("leave buf_sk_ecdsa_verify, ret=%d", ret))

  return ret;

}

#endif /* DROPBEAR_SK_ECDSA */