EVP_get_digestbynid() and ENGINE_get_digest()

[cellecial]

Hi,

We had a product which generate RSA/MD5 certificate.
Now I'm working on a custom openssl engine.
The goal is to generate X509 certificate with some new signature/digest
algorithms.
With engine, we do not need to re-code too much.

Now we can generate and sign certificate, but X509_verify() failed.
The error is :

X509_verify() fail
33436:error:0D0C50A1:asn1 encoding routines:ASN1_item_verify:unknown
message digest
algorithm:d:\work\newalg\openssl-1.0.1c\crypto\asn1\a_verify.c:174:

a_verify.c:
----------------------------------------------------------
const EVP_MD *type;
  type=EVP_get_digestbynid(mdnid);
  if (type == NULL)
   {
   ASN1err(ASN1_F_ASN1_ITEM_VERIFY,ASN1_R_UNKNOWN_MESSAGE_DIGEST_ALGORITHM);
   goto err;
   }
-------------------------------------------------------------



I wrote a small test :

===================================
EVP_MD *md1,*md2;

OpenSSL_add_all_algorithms();
ENGINE_load_openssl();
 ENGINE_load_newalg();
 e = ENGINE_by_id("newalg");
 if(!ENGINE_set_default(e, ENGINE_METHOD_ALL))
 {
  printf("can't use that engine\n");
  ENGINE_free(e);
  return ;
 }

md1 = ENGINE_get_digest(e, NID_MyDigestAlgor);

md2 = EVP_get_digestbynid(NID_MyDigestAlgor);

===================================

The result is : md1 is not NULL  , and md2 is NULL.

I think X509_verify()  is calling EVP_get_digestbynid() to get digest
algorithm, but if it doesn't find digest algorithm in engine algorithm
list, how can I use X509_verify() ?

Thank you for your hint.

(Sorry to post a question without subject one minute ago.)