openpgp: Add a policy object.

  - Change all functions that need to evaluate the validity of a
    signature (either directly or indirectly to take a policy object.

  - Use the policy object to allow the user to place additional
    constraints on a signature's validity.

  - This addresses the first half of #274 (it introduces the policy
    object, but does not yet implement any policy).

1 files changed, 4 insertions, 1 deletions

diff --git a/ipc/examples/gpg-agent-sign.rs b/ipc/examples/gpg-agent-sign.rs
index a80f3935..424f2a74 100644
--- a/ipc/examples/gpg-agent-sign.rs
+++ b/ipc/examples/gpg-agent-sign.rs
@@ -9,9 +9,12 @@ extern crate sequoia_ipc as ipc;
 use crate::openpgp::armor;
 use crate::openpgp::parse::Parse;
 use crate::openpgp::serialize::stream::{Message, LiteralWriter, Signer};
+use crate::openpgp::policy::StandardPolicy as P;
 use crate::ipc::gnupg::{Context, KeyPair};
 
 fn main() {
+    let p = &P::new();
+
     let matches = clap::App::new("gpg-agent-sign")
         .version(env!("CARGO_PKG_VERSION"))
         .about("Connects to gpg-agent and creates a dummy signature.")
@@ -39,7 +42,7 @@ fn main() {
 
     // Construct a KeyPair for every signing-capable (sub)key.
     let mut signers = certs.iter().flat_map(|cert| {
-        cert.keys().policy(None).alive().revoked(false).for_signing()
+        cert.keys().set_policy(p, None).alive().revoked(false).for_signing()
             .filter_map(|ka| {
                 KeyPair::new(&ctx, ka.key()).ok()
             })