ArmorUtils now prints out the primary user-id and brief information about other user-ids

pgpainless-core/src/main/java/org/pgpainless/util/ArmorUtils.java

@@ -24,6 +24,7 @@ import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
 import org.bouncycastle.openpgp.PGPSecretKey;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
+import org.bouncycastle.openpgp.PGPSignature;
 import org.bouncycastle.openpgp.PGPUtil;
 import org.bouncycastle.openpgp.operator.KeyFingerPrintCalculator;
 import org.bouncycastle.util.io.Streams;
@@ -106,14 +107,38 @@ public final class ArmorUtils {
         return sb.toString();
     }
 
+    private static Tuple<String, Integer> getPrimaryUserIdAndUserIdCount(PGPPublicKey publicKey) {
+        Iterator<String> userIds = publicKey.getUserIDs();
+        int countIdentities = 0;
+        String primary = null;
+        while (userIds.hasNext()) {
+            countIdentities++;
+            String userId = userIds.next();
+            if (primary == null) {
+                Iterator<PGPSignature> signatures = publicKey.getSignaturesForID(userId);
+                while (signatures.hasNext()) {
+                    PGPSignature signature = signatures.next();
+                    if (signature.getHashedSubPackets().isPrimaryUserID()) {
+                        primary = userId;
+                        break;
+                    }
+                }
+            }
+        }
+        return new Tuple<>(primary, countIdentities);
+    }
+
     private static MultiMap<String, String> keyToHeader(PGPPublicKey publicKey) {
         MultiMap<String, String> header = new MultiMap<>();
         OpenPgpFingerprint fingerprint = OpenPgpFingerprint.of(publicKey);
-        Iterator<String> userIds = publicKey.getUserIDs();
 
         header.put(HEADER_COMMENT, fingerprint.prettyPrint());
-        if (userIds.hasNext()) {
+        Tuple<String, Integer> idCount = getPrimaryUserIdAndUserIdCount(publicKey);
-            header.put(HEADER_COMMENT, userIds.next());
+        if (idCount.getA() != null) {
+            header.put(HEADER_COMMENT, idCount.getA() + " (Primary)");
+        }
+        if (idCount.getB() != 1) {
+            header.put(HEADER_COMMENT, String.format("Public key contains %d identities", idCount.getB()));
         }
         return header;
     }

pgpainless-core/src/test/java/org/pgpainless/util/ArmorUtilsTest.java

@@ -21,16 +21,24 @@ import org.bouncycastle.openpgp.PGPCompressedData;
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPLiteralData;
 import org.bouncycastle.openpgp.PGPObjectFactory;
+import org.bouncycastle.openpgp.PGPPublicKey;
+import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.bouncycastle.openpgp.PGPUtil;
 import org.bouncycastle.util.io.Streams;
 import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestTemplate;
 import org.junit.jupiter.api.extension.ExtendWith;
+import org.pgpainless.PGPainless;
 import org.pgpainless.algorithm.HashAlgorithm;
+import org.pgpainless.algorithm.KeyFlag;
 import org.pgpainless.implementation.ImplementationFactory;
 import org.pgpainless.key.TestKeys;
+import org.pgpainless.key.generation.KeySpec;
+import org.pgpainless.key.generation.type.ecc.EllipticCurve;
+import org.pgpainless.key.generation.type.ecc.ecdsa.ECDSA;
 
 public class ArmorUtilsTest {
 
@@ -144,6 +152,53 @@ public class ArmorUtilsTest {
                 "-----END PGP MESSAGE-----\n", out.toString());
     }
 
+    @Test
+    public void testMultipleIdentitiesInHeader() throws Exception {
+        PGPSecretKeyRing secretKeyRing = PGPainless.buildKeyRing()
+                .setPrimaryKey(KeySpec.getBuilder(ECDSA.fromCurve(EllipticCurve._P256), KeyFlag.SIGN_DATA, KeyFlag.CERTIFY_OTHER))
+                .addUserId("Juliet <juliet@montague.lit>")
+                .addUserId("xmpp:juliet@capulet.lit")
+                .setPassphrase(Passphrase.fromPassword("test"))
+                .build();
+        PGPPublicKey publicKey = secretKeyRing.getPublicKey();
+        PGPPublicKeyRing publicKeyRing = PGPainless.readKeyRing().publicKeyRing(publicKey.getEncoded());
+        String armored = PGPainless.asciiArmor(publicKeyRing);
+        Assertions.assertTrue(armored.contains("Comment: Juliet <juliet@montague.lit> (Primary)"));
+        Assertions.assertTrue(armored.contains("Comment: Public key contains 2 identities"));
+    }
+
+    @Test
+    public void testSingleIdentityInHeader() throws Exception {
+        PGPSecretKeyRing secretKeyRing = PGPainless.buildKeyRing()
+                .setPrimaryKey(KeySpec.getBuilder(ECDSA.fromCurve(EllipticCurve._P256), KeyFlag.SIGN_DATA, KeyFlag.CERTIFY_OTHER))
+                .addUserId("Juliet <juliet@montague.lit>")
+                .setPassphrase(Passphrase.fromPassword("test"))
+                .build();
+        PGPPublicKey publicKey = secretKeyRing.getPublicKey();
+        PGPPublicKeyRing publicKeyRing = PGPainless.readKeyRing().publicKeyRing(publicKey.getEncoded());
+        String armored = PGPainless.asciiArmor(publicKeyRing);
+        Assertions.assertTrue(armored.contains("Comment: Juliet <juliet@montague.lit> (Primary)"));
+        Assertions.assertFalse(armored.contains("Comment: Public key contains 1 identities"));
+    }
+
+    @Test
+    public void testWithoutIdentityInHeader() throws Exception {
+        PGPPublicKeyRing publicKeys = PGPainless.readKeyRing().publicKeyRing("-----BEGIN PGP PUBLIC KEY BLOCK-----\n" +
+                "\n" +
+                "xsBNBGIgzE0BCACwxaYg6bpmp0POq1T6yalGE9XaL2IG9d9khDBweZ63s3Pu1pHB\n" +
+                "JtmjgN7Tx3ts6hLzQm3YKYA6zu1MXQ8k2vqtdtGUpZPp18Pbars7yUDqh8QIdFjO\n" +
+                "GeE+c8So0MQgTgoBuyZiSmslwp1WO78ozf/0rCayFdy73dPUntuLE6c2ZKO8nw/g\n" +
+                "uyk2ozsqLN/TBpgbuJUyMedJtXV10DdT9QxH/66LmdjFKXTkc74qI8YAm/pmJeOh\n" +
+                "36qZ5ehAgz9MthPQINnZKpnqidqkGFvjwVFlCMlVSmNCNJmpgGDH3gvkklZHzGsf\n" +
+                "dfzQswd/BQjPsFH9cK+QFYMG6q2zrvM0X9mdABEBAAE=\n" +
+                "=njg8\n" +
+                "-----END PGP PUBLIC KEY BLOCK-----\n");
+        PGPPublicKey publicKey = publicKeys.getPublicKey();
+        PGPPublicKeyRing publicKeyRing = PGPainless.readKeyRing().publicKeyRing(publicKey.getEncoded());
+        String armored = PGPainless.asciiArmor(publicKeyRing);
+        Assertions.assertTrue(armored.contains("Comment: Public key contains 0 identities"));
+    }
+
     @TestTemplate
     @ExtendWith(TestAllImplementations.class)
     public void decodeExampleTest() throws IOException, PGPException {