Add deprecated utility methods for deleting user-ids from keys/certif…

…icates

pgpainless-core/src/main/java/org/pgpainless/key/util/KeyRingUtils.java

@@ -154,4 +154,50 @@ public static boolean keyRingContainsKeyWithId(@Nonnull PGPPublicKeyRing ring,
                                                    long keyId) {
         return ring.getPublicKey(keyId) != null;
     }
+
+    /**
+     * Delete the given user-id and its certification signatures from the given key.
+     *
+     * @deprecated Deleting user-ids is highly discouraged, since it might lead to all sorts of problems
+     * (e.g. lost key properties).
+     * Instead, user-ids should only be revoked.
+     *
+     * @param secretKeys secret keys
+     * @param userId user-id
+     * @return modified secret keys
+     */
+    @Deprecated
+    public PGPSecretKeyRing deleteUserIdFromSecretKeyRing(PGPSecretKeyRing secretKeys, String userId) {
+        PGPSecretKey secretKey = secretKeys.getSecretKey(); // user-ids are located on primary key only
+        PGPPublicKey publicKey = secretKey.getPublicKey(); // user-ids are placed on the public key part
+        publicKey = PGPPublicKey.removeCertification(publicKey, userId);
+        if (publicKey == null) {
+            throw new NoSuchElementException("User-ID " + userId + " not found on the key.");
+        }
+        secretKey = PGPSecretKey.replacePublicKey(secretKey, publicKey);
+        secretKeys = PGPSecretKeyRing.insertSecretKey(secretKeys, secretKey);
+        return secretKeys;
+    }
+
+    /**
+     * Delete the given user-id and its certification signatures from the given certificate.
+     *
+     * @deprecated Deleting user-ids is highly discouraged, since it might lead to all sorts of problems
+     * (e.g. lost key properties).
+     * Instead, user-ids should only be revoked.
+     *
+     * @param publicKeys certificate
+     * @param userId user-id
+     * @return modified secret keys
+     */
+    @Deprecated
+    public PGPPublicKeyRing deleteUserIdFromPublicKeyRing(PGPPublicKeyRing publicKeys, String userId) {
+        PGPPublicKey publicKey = publicKeys.getPublicKey(); // user-ids are located on primary key only
+        publicKey = PGPPublicKey.removeCertification(publicKey, userId);
+        if (publicKey == null) {
+            throw new NoSuchElementException("User-ID " + userId + " not found on the key.");
+        }
+        publicKeys = PGPPublicKeyRing.insertPublicKey(publicKeys, publicKey);
+        return publicKeys;
+    }
 }