openpgp: Remove SignatureBuilder::set_key_expiration_time.

  - Internally, we work with relative times, not absolute times.

  - Working with absolute times is error prone: when setting the key
    expiration should it be relative to the current value of the
    Signature Creation subpacket or the one when the SignatureBuilder
    is finalized?

  - Just remove `SignatureBuilder::set_key_expiration_time.`

1 files changed, 0 insertions, 26 deletions

diff --git a/openpgp/src/packet/signature/subpacket.rs b/openpgp/src/packet/signature/subpacket.rs
index a67cf7d0..875a3a73 100644
--- a/openpgp/src/packet/signature/subpacket.rs
+++ b/openpgp/src/packet/signature/subpacket.rs
@@ -2529,32 +2529,6 @@ impl signature::SignatureBuilder {
         Ok(self)
     }
 
-    /// Sets the value of the Key Expiration Time subpacket.
-    ///
-    /// If `None` is given, any expiration subpacket is removed.
-    pub fn set_key_expiration_time<P, R>(
-        self,
-        key: &Key<P, R>,
-        expiration: Option<time::SystemTime>)
-        -> Result<Self>
-        where P: key::KeyParts,
-              R: key::KeyRole,
-    {
-        if let Some(e) = expiration.map(crate::types::normalize_systemtime) {
-            let ct = key.creation_time();
-            let vp = match e.duration_since(ct) {
-                Ok(v) => v,
-                Err(_) => return Err(Error::InvalidArgument(
-                    format!("Expiration time {:?} predates creation time \
-                             {:?}", e, ct)).into()),
-            };
-
-            self.set_key_validity_period(Some(vp))
-        } else {
-            self.set_key_validity_period(None)
-        }
-    }
-
     /// Sets the value of the Preferred Symmetric Algorithms
     /// subpacket, which contains the list of symmetric algorithms
     /// that the key holder prefers, ordered according by the key