openpgp: Replace TPK::select_keys with an iterator.

  - TPK::select_keys mixes iterating and filtering.

  - Make KeyIter an implicit builder, which supports convenient
    filtering.

  - Provide a convenience function to key an iterator with a
    reasonable filter default.

2 files changed, 8 insertions, 3 deletions

diff --git a/tool/src/commands/mod.rs b/tool/src/commands/mod.rs
index db713caa..076bafbc 100644
--- a/tool/src/commands/mod.rs
+++ b/tool/src/commands/mod.rs
@@ -44,7 +44,10 @@ fn tm2str(t: &time::Tm) -> String {
 fn get_signing_keys(tpks: &[openpgp::TPK]) -> Result<Vec<crypto::KeyPair>> {
     let mut keys = Vec::new();
     'next_tpk: for tsk in tpks {
-        for key in tsk.select_signing_keys(None) {
+        for key in tsk.keys_valid()
+            .signing_capable()
+            .map(|k| k.2)
+        {
             if let Some(mut secret) = key.secret() {
                 let secret_mpis = match secret {
                     SecretKey::Encrypted { .. } => {
@@ -191,7 +194,9 @@ impl<'a> VerificationHelper for VHelper<'a> {
         let mut tpks = self.tpks.take().unwrap();
         let seen: HashSet<_> = tpks.iter()
             .flat_map(|tpk| {
-                tpk.keys().map(|(_, _, key)| key.fingerprint().to_keyid())
+                // Even if a key is revoked or expired, we can still
+                // use it to verify a message.
+                tpk.keys_all().map(|(_, _, key)| key.fingerprint().to_keyid())
             }).collect();
 
         // Explicitly provided keys are trusted.
diff --git a/tool/tests/sq-sign.rs b/tool/tests/sq-sign.rs
index 90da8d8a..8a891f65 100644
--- a/tool/tests/sq-sign.rs
+++ b/tool/tests/sq-sign.rs
@@ -208,7 +208,7 @@ fn sq_sign_append_on_compress_then_sign() {
     // message by foot.
     let tsk = TPK::from_file(&p("keys/dennis-simon-anton-private.pgp"))
         .unwrap();
-    let key = tsk.select_signing_keys(None)[0];
+    let key = tsk.keys_all().signing_capable().nth(0).unwrap().2;
     let sec = match key.secret() {
         Some(SecretKey::Unencrypted { ref mpis }) => mpis,
         _ => unreachable!(),