From bc5dc50b788ec4826dde1ab32cb4fbc72df5eba3 Mon Sep 17 00:00:00 2001
From: Paul Schaub <vanitasvitae@fsfe.org>
Date: Tue, 9 Aug 2022 15:08:59 +0200
Subject: [PATCH] Add KeyRingInfo.isSigningCapable()

Fixes #307
---
 .../org/pgpainless/key/info/KeyRingInfo.java  | 28 ++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java b/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java
index 85cc8f28..cb328300 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java
@@ -1051,10 +1051,36 @@ public class KeyRingInfo {
         return isKeyValidlyBound(getKeyId()) && !getEncryptionSubkeys(purpose).isEmpty();
     }
 
-    public boolean isUsableForSigning() {
+    /**
+     * Returns true, if the key ring is capable of signing.
+     * Contrary to {@link #isUsableForSigning()}, this method also returns true, if this {@link KeyRingInfo} is based
+     * on a key ring which has at least one valid public key marked for signing.
+     * The secret key is not required for the key ring to qualify as signing capable.
+     *
+     * @return true if key corresponding to the cert is capable of signing
+     */
+    public boolean isSigningCapable() {
+        // check if primary-key is revoked / expired
         if (!isKeyValidlyBound(getKeyId())) {
             return false;
         }
+        // check if it has signing-capable key
+        return !getSigningSubkeys().isEmpty();
+    }
+
+    /**
+     * Returns true, if this {@link KeyRingInfo} is based on a {@link PGPSecretKeyRing}, which has a valid signing key
+     * which is ready to be used (i.e. secret key is present and is not on a smart-card).
+     *
+     * If you just want to check, whether a key / certificate has signing capable subkeys,
+     * use {@link #isSigningCapable()} instead.
+     *
+     * @return true if key is ready to be used for signing
+     */
+    public boolean isUsableForSigning() {
+        if (!isSigningCapable()) {
+            return false;
+        }
 
         List<PGPPublicKey> signingKeys = getSigningSubkeys();
         for (PGPPublicKey pk : signingKeys) {