view libtomcrypt/testprof/dsa_test.c @ 1788:1fc0012b9c38

Fix handling of replies to global requests (#112) The current code assumes that all global requests want / need a reply. This isn't always true and the request itself indicates if it wants a reply or not. It causes a specific problem with [email protected] messages. These are sent by OpenSSH after authentication to inform the client of potential other host keys for the host. This can be used to add a new type of host key or to rotate host keys. The initial information message from the server is sent as a global request, but with want_reply set to false. This means that the server doesn't expect an answer to this message. Instead the client needs to send a prove request as a reply if it wants to receive proof of ownership for the host keys. The bug doesn't cause any current problems with due to how OpenSSH treats receiving the failure message. It instead treats it as a keepalive message and further ignores it. Arguably this is a protocol violation though of Dropbear and it is only accidental that it doesn't cause a problem with OpenSSH. The bug was found when adding host keys support to libssh, which is more strict protocol wise and treats the unexpected failure message an error, also see https://gitlab.com/libssh/libssh-mirror/-/merge_requests/145 for more information. The fix here is to honor the want_reply flag in the global request and to only send a reply if the other side expects a reply.
author Dirkjan Bussink <d.bussink@gmail.com>
date Thu, 10 Dec 2020 16:13:13 +0100
parents f849a5ca2efc
children
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line source

#include <tomcrypt_test.h>

#ifdef LTC_MDSA

int dsa_test(void)
{
   unsigned char msg[16], out[1024], out2[1024];
   unsigned long x, y;
   int stat1, stat2;
   dsa_key key, key2;

   /* make a random key */
   DO(dsa_make_key(&yarrow_prng, find_prng("yarrow"), 20, 128, &key));

   /* verify it */
   DO(dsa_verify_key(&key, &stat1));
   if (stat1 == 0) { fprintf(stderr, "dsa_verify_key "); return 1; }
   
   /* encrypt a message */
   for (x = 0; x < 16; x++) { msg[x] = x; }
   x = sizeof(out);
   DO(dsa_encrypt_key(msg, 16, out, &x, &yarrow_prng, find_prng("yarrow"), find_hash("sha1"), &key));
   
   /* decrypt */
   y = sizeof(out2);
   DO(dsa_decrypt_key(out, x, out2, &y, &key));
   
   if (y != 16 || memcmp(out2, msg, 16)) {
      fprintf(stderr, "dsa_decrypt failed, y == %lu\n", y);
      return 1;
   }

   /* sign the message */
   x = sizeof(out);
   DO(dsa_sign_hash(msg, sizeof(msg), out, &x, &yarrow_prng, find_prng("yarrow"), &key));

   /* verify it once */
   DO(dsa_verify_hash(out, x, msg, sizeof(msg), &stat1, &key));

   /* Modify and verify again */
   msg[0] ^= 1;
   DO(dsa_verify_hash(out, x, msg, sizeof(msg), &stat2, &key));
   msg[0] ^= 1;
   if (!(stat1 == 1 && stat2 == 0)) { fprintf(stderr, "dsa_verify %d %d", stat1, stat2); return 1; }

   /* test exporting it */
   x = sizeof(out2);
   DO(dsa_export(out2, &x, PK_PRIVATE, &key));
   DO(dsa_import(out2, x, &key2));

   /* verify a signature with it */
   DO(dsa_verify_hash(out, x, msg, sizeof(msg), &stat1, &key2));
   if (stat1 == 0) { fprintf(stderr, "dsa_verify (import private) %d ", stat1); return 1; }
   dsa_free(&key2);

   /* export as public now */
   x = sizeof(out2);
   DO(dsa_export(out2, &x, PK_PUBLIC, &key));

   DO(dsa_import(out2, x, &key2));
   /* verify a signature with it */
   DO(dsa_verify_hash(out, x, msg, sizeof(msg), &stat1, &key2));
   if (stat1 == 0) { fprintf(stderr, "dsa_verify (import public) %d ", stat1); return 1; }
   dsa_free(&key2);
   dsa_free(&key);

   return 0;
}

#else

int dsa_test(void)
{
  fprintf(stderr, "NOP");
  return 0;
}

#endif

/* $Source$ */
/* $Revision$ */
/* $Date$ */