openpgp: Drop Cert::direct_key_signature.

  - Methods on Cert should not take a policy.  Instead, the
    corresponding method on ValidCert should be used.

  - See #484.

1 files changed, 1 insertions, 13 deletions

diff --git a/openpgp/src/cert/mod.rs b/openpgp/src/cert/mod.rs
index bcc0ee16..c228b03c 100644
--- a/openpgp/src/cert/mod.rs
+++ b/openpgp/src/cert/mod.rs
@@ -675,18 +675,6 @@ impl Cert {
         PrimaryKeyAmalgamation::new(&self)
     }
 
-    /// Returns the Certificate's direct key signature as of the
-    /// reference time, if any.
-    ///
-    /// Subpackets on direct key signatures apply to all components of
-    /// the certificate.
-    pub fn direct_key_signature<T>(&self, policy: &dyn Policy, t: T)
-        -> Result<&Signature>
-        where T: Into<Option<time::SystemTime>>
-    {
-        self.primary.binding_signature(policy, t)
-    }
-
     /// Returns the Cert's revocation status at time `t`.
     ///
     /// A Cert is revoked at time `t` if:
@@ -1655,7 +1643,7 @@ impl<'a> ValidCert<'a> {
     /// the certificate.
     pub fn direct_key_signature(&self) -> Result<&'a Signature>
     {
-        self.cert.direct_key_signature(self.policy(), self.time())
+        self.cert.primary.binding_signature(self.policy(), self.time())
     }
 
     /// Returns the Cert's revocation status.