Stop marking default digest for EC keys as mandatory

ASN1_PKEY_CTRL_DEFAULT_MD_NID is documented to return 2 for a mandatory
digest algorithm, when the key can't support any others. That isn't true
here, so return 1 instead.

Partially fixes #7348

Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit eb7eb1378cd15c4652884b3701d4c0ef27b5b8a6)

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7609)

diff --git a/crypto/ec/ec_ameth.c b/crypto/ec/ec_ameth.c
index a3164b5b2ed9743854f7a2c209a869f30d3d0151..8b363e096beda464ab5352467bc435006cf5f54a 100644 (file)
--- a/crypto/ec/ec_ameth.c
+++ b/crypto/ec/ec_ameth.c
@@ -505,7 +505,7 @@ static int ec_pkey_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
 
     case ASN1_PKEY_CTRL_DEFAULT_MD_NID:
         *(int *)arg2 = NID_sha256;
-        return 2;
+        return 1;
 
     case ASN1_PKEY_CTRL_SET1_TLS_ENCPT:
         return EC_KEY_oct2key(EVP_PKEY_get0_EC_KEY(pkey), arg2, arg1, NULL);