Fix EC curve detection.

  - Some systems have smaller set of supported curves and even though the
    curve identifiers are compiled in the usage of the curve fails.

  - Try to construct an `EcGroup` using retrieved `Nid` as this is a cheap
    check that will fail if the curve is truly unsupported.

  - Fixes #976.

1 files changed, 5 insertions, 1 deletions

diff --git a/openpgp/src/crypto/backend/openssl.rs b/openpgp/src/crypto/backend/openssl.rs
index 4e610bfe..aa5c9db7 100644
--- a/openpgp/src/crypto/backend/openssl.rs
+++ b/openpgp/src/crypto/backend/openssl.rs
@@ -43,7 +43,11 @@ impl Curve {
         } else {
             // the rest of EC algorithms are supported via the same
             // codepath
-            openssl::nid::Nid::try_from(self).is_ok()
+            if let Ok(nid) = openssl::nid::Nid::try_from(self) {
+                openssl::ec::EcGroup::from_curve_name(nid).is_ok()
+            } else {
+                false
+            }
         }
     }
 }