From 3a9473ad6c57b8abb6d1344a02fbe2aaec20f03b Mon Sep 17 00:00:00 2001
From: Paul Schaub <vanitasvitae@fsfe.org>
Date: Wed, 27 Oct 2021 17:38:25 +0200
Subject: [PATCH] V5 Key-readyness: Replace usages of OpenPgpV4Fingerprint with
 abstract super class

---
 .../OpenPgpMetadata.java                      |  6 ++--
 .../encryption_signing/EncryptionOptions.java |  4 +--
 .../encryption_signing/SigningOptions.java    |  4 +--
 .../pgpainless/key/OpenPgpFingerprint.java    |  7 ++---
 .../pgpainless/key/OpenPgpV4Fingerprint.java  | 10 +++----
 .../org/pgpainless/key/SubkeyIdentifier.java  | 28 +++++++++----------
 .../org/pgpainless/key/info/KeyRingInfo.java  | 18 ++++++------
 .../secretkeyring/SecretKeyRingEditor.java    | 14 +++++-----
 .../SecretKeyRingEditorInterface.java         | 12 ++++----
 .../CachingSecretKeyRingProtector.java        |  4 +--
 .../signature/DetachedSignatureCheck.java     |  6 ++--
 .../signature/OnePassSignatureCheck.java      |  3 +-
 .../pgpainless/signature/SignatureUtils.java  | 10 +++++--
 .../signature/SignatureValidator.java         |  6 ++--
 .../subpackets/SignatureSubpacketsUtil.java   | 12 ++++----
 .../java/org/pgpainless/util/ArmorUtils.java  |  4 +--
 .../signature/SignatureStructureTest.java     |  2 +-
 17 files changed, 78 insertions(+), 72 deletions(-)

diff --git a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMetadata.java b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMetadata.java
index 48afd5af..9dfc8076 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMetadata.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMetadata.java
@@ -23,7 +23,7 @@ import org.pgpainless.algorithm.CompressionAlgorithm;
 import org.pgpainless.algorithm.StreamEncoding;
 import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import org.pgpainless.exception.SignatureValidationException;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.SubkeyIdentifier;
 
 public class OpenPgpMetadata {
@@ -201,7 +201,7 @@ public class OpenPgpMetadata {
      */
     public boolean containsVerifiedSignatureFrom(PGPPublicKeyRing certificate) {
         for (PGPPublicKey key : certificate) {
-            OpenPgpV4Fingerprint fingerprint = new OpenPgpV4Fingerprint(key);
+            OpenPgpFingerprint fingerprint = OpenPgpFingerprint.of(key);
             if (containsVerifiedSignatureFrom(fingerprint)) {
                 return true;
             }
@@ -218,7 +218,7 @@ public class OpenPgpMetadata {
      * @param fingerprint fingerprint of primary key or signing subkey
      * @return true if validly signed, false otherwise
      */
-    public boolean containsVerifiedSignatureFrom(OpenPgpV4Fingerprint fingerprint) {
+    public boolean containsVerifiedSignatureFrom(OpenPgpFingerprint fingerprint) {
         for (SubkeyIdentifier verifiedSigningKey : getVerifiedSignatures().keySet()) {
             if (verifiedSigningKey.getPrimaryKeyFingerprint().equals(fingerprint) ||
                     verifiedSigningKey.getSubkeyFingerprint().equals(fingerprint)) {
diff --git a/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/EncryptionOptions.java b/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/EncryptionOptions.java
index b75e0081..65948168 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/EncryptionOptions.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/EncryptionOptions.java
@@ -23,7 +23,7 @@ import org.bouncycastle.openpgp.operator.PGPKeyEncryptionMethodGenerator;
 import org.pgpainless.algorithm.EncryptionPurpose;
 import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import org.pgpainless.implementation.ImplementationFactory;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.SubkeyIdentifier;
 import org.pgpainless.key.info.KeyAccessor;
 import org.pgpainless.key.info.KeyRingInfo;
@@ -187,7 +187,7 @@ public class EncryptionOptions {
         KeyRingInfo info = new KeyRingInfo(key, new Date());
         Date primaryKeyExpiration = info.getPrimaryKeyExpirationDate();
         if (primaryKeyExpiration != null && primaryKeyExpiration.before(new Date())) {
-            throw new IllegalArgumentException("Provided key " + new OpenPgpV4Fingerprint(key) + " is expired: " + primaryKeyExpiration.toString());
+            throw new IllegalArgumentException("Provided key " + OpenPgpFingerprint.of(key) + " is expired: " + primaryKeyExpiration);
         }
         List<PGPPublicKey> encryptionSubkeys = encryptionKeySelectionStrategy
                 .selectEncryptionSubkeys(info.getEncryptionSubkeys(purpose));
diff --git a/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/SigningOptions.java b/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/SigningOptions.java
index 651e96ea..c1714c89 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/SigningOptions.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/encryption_signing/SigningOptions.java
@@ -27,7 +27,7 @@ import org.pgpainless.algorithm.negotiation.HashAlgorithmNegotiator;
 import org.pgpainless.exception.KeyCannotSignException;
 import org.pgpainless.exception.KeyValidationError;
 import org.pgpainless.implementation.ImplementationFactory;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.SubkeyIdentifier;
 import org.pgpainless.key.info.KeyRingInfo;
 import org.pgpainless.key.protection.SecretKeyRingProtector;
@@ -159,7 +159,7 @@ public final class SigningOptions {
 
         List<PGPPublicKey> signingPubKeys = keyRingInfo.getSigningSubkeys();
         if (signingPubKeys.isEmpty()) {
-            throw new KeyCannotSignException("Key " + new OpenPgpV4Fingerprint(secretKey) + " has no valid signing key.");
+            throw new KeyCannotSignException("Key " + OpenPgpFingerprint.of(secretKey) + " has no valid signing key.");
         }
 
         for (PGPPublicKey signingPubKey : signingPubKeys) {
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpFingerprint.java b/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpFingerprint.java
index e9db3f5e..318f7a05 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpFingerprint.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpFingerprint.java
@@ -16,9 +16,8 @@ import org.bouncycastle.util.encoders.Hex;
 /**
  * Abstract super class of different version OpenPGP fingerprints.
  *
- * @param <C> subclass type
  */
-public abstract class OpenPgpFingerprint<C extends OpenPgpV4Fingerprint> implements CharSequence, Comparable<C> {
+public abstract class OpenPgpFingerprint implements CharSequence, Comparable<OpenPgpFingerprint> {
     protected static final Charset utf8 = Charset.forName("UTF-8");
     protected final String fingerprint;
 
@@ -29,7 +28,7 @@ public abstract class OpenPgpFingerprint<C extends OpenPgpV4Fingerprint> impleme
      * @param key key
      * @return fingerprint
      */
-    public static OpenPgpFingerprint<?> of(PGPPublicKey key) {
+    public static OpenPgpFingerprint of(PGPPublicKey key) {
         if (key.getVersion() == 4) {
             return new OpenPgpV4Fingerprint(key);
         }
@@ -43,7 +42,7 @@ public abstract class OpenPgpFingerprint<C extends OpenPgpV4Fingerprint> impleme
      * @param ring key ring
      * @return fingerprint
      */
-    public static OpenPgpFingerprint<?> of(PGPKeyRing ring) {
+    public static OpenPgpFingerprint of(PGPKeyRing ring) {
         return of(ring.getPublicKey());
     }
 
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpV4Fingerprint.java b/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpV4Fingerprint.java
index a1e6eb7f..b5b3d4a7 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpV4Fingerprint.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/OpenPgpV4Fingerprint.java
@@ -18,9 +18,9 @@ import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.bouncycastle.util.encoders.Hex;
 
 /**
- * This class represents an hex encoded, uppercase OpenPGP v4 fingerprint.
+ * This class represents a hex encoded, uppercase OpenPGP v4 fingerprint.
  */
-public class OpenPgpV4Fingerprint extends OpenPgpFingerprint<OpenPgpV4Fingerprint> {
+public class OpenPgpV4Fingerprint extends OpenPgpFingerprint {
 
     public static final String SCHEME = "openpgp4fpr";
 
@@ -129,7 +129,7 @@ public class OpenPgpV4Fingerprint extends OpenPgpFingerprint<OpenPgpV4Fingerprin
     }
 
     /**
-     * Convert a openpgp4fpr URI to an {@link OpenPgpV4Fingerprint}.
+     * Convert an openpgp4fpr URI to an {@link OpenPgpV4Fingerprint}.
      *
      * @param uri {@link URI} with scheme 'openpgp4fpr'
      * @return fingerprint parsed from the uri
@@ -143,7 +143,7 @@ public class OpenPgpV4Fingerprint extends OpenPgpFingerprint<OpenPgpV4Fingerprin
     }
 
     @Override
-    public int compareTo(@Nonnull OpenPgpV4Fingerprint openPgpV4Fingerprint) {
-        return toString().compareTo(openPgpV4Fingerprint.toString());
+    public int compareTo(@Nonnull OpenPgpFingerprint openPgpFingerprint) {
+        return toString().compareTo(openPgpFingerprint.toString());
     }
 }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/SubkeyIdentifier.java b/pgpainless-core/src/main/java/org/pgpainless/key/SubkeyIdentifier.java
index afd093af..8bfd7f7c 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/SubkeyIdentifier.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/SubkeyIdentifier.java
@@ -16,8 +16,8 @@ import org.bouncycastle.openpgp.PGPPublicKey;
  */
 public class SubkeyIdentifier {
 
-    private final OpenPgpV4Fingerprint primaryKeyFingerprint;
-    private final OpenPgpV4Fingerprint subkeyFingerprint;
+    private final OpenPgpFingerprint primaryKeyFingerprint;
+    private final OpenPgpFingerprint subkeyFingerprint;
 
     /**
      * Create a {@link SubkeyIdentifier} from a {@link PGPKeyRing}.
@@ -31,7 +31,7 @@ public class SubkeyIdentifier {
 
     /**
      * Create a {@link SubkeyIdentifier} from a {@link PGPKeyRing} and the subkeys key id.
-     * {@link #getPrimaryKeyFingerprint()} will return the {@link OpenPgpV4Fingerprint} of the keyrings primary key,
+     * {@link #getPrimaryKeyFingerprint()} will return the {@link OpenPgpFingerprint} of the keyrings primary key,
      * while {@link #getSubkeyFingerprint()} will return the subkeys fingerprint.
      *
      * @param keyRing keyring the subkey belongs to
@@ -42,12 +42,12 @@ public class SubkeyIdentifier {
         if (subkey == null) {
             throw new NoSuchElementException("Key ring does not contain subkey with id " + Long.toHexString(keyId));
         }
-        this.primaryKeyFingerprint = new OpenPgpV4Fingerprint(keyRing);
-        this.subkeyFingerprint = new OpenPgpV4Fingerprint(subkey);
+        this.primaryKeyFingerprint = OpenPgpFingerprint.of(keyRing);
+        this.subkeyFingerprint = OpenPgpFingerprint.of(subkey);
     }
 
-    public SubkeyIdentifier(@Nonnull PGPKeyRing keyRing, @Nonnull OpenPgpV4Fingerprint subkeyFingerprint) {
-        this(new OpenPgpV4Fingerprint(keyRing), subkeyFingerprint);
+    public SubkeyIdentifier(@Nonnull PGPKeyRing keyRing, @Nonnull OpenPgpFingerprint subkeyFingerprint) {
+        this(OpenPgpFingerprint.of(keyRing), subkeyFingerprint);
     }
 
     /**
@@ -56,7 +56,7 @@ public class SubkeyIdentifier {
      *
      * @param primaryKeyFingerprint fingerprint of the identified key
      */
-    public SubkeyIdentifier(@Nonnull OpenPgpV4Fingerprint primaryKeyFingerprint) {
+    public SubkeyIdentifier(@Nonnull OpenPgpFingerprint primaryKeyFingerprint) {
         this(primaryKeyFingerprint, primaryKeyFingerprint);
     }
 
@@ -67,12 +67,12 @@ public class SubkeyIdentifier {
      * @param primaryKeyFingerprint fingerprint of the primary key
      * @param subkeyFingerprint fingerprint of the subkey
      */
-    public SubkeyIdentifier(@Nonnull OpenPgpV4Fingerprint primaryKeyFingerprint, @Nonnull OpenPgpV4Fingerprint subkeyFingerprint) {
+    public SubkeyIdentifier(@Nonnull OpenPgpFingerprint primaryKeyFingerprint, @Nonnull OpenPgpFingerprint subkeyFingerprint) {
         this.primaryKeyFingerprint = primaryKeyFingerprint;
         this.subkeyFingerprint = subkeyFingerprint;
     }
 
-    public @Nonnull OpenPgpV4Fingerprint getFingerprint() {
+    public @Nonnull OpenPgpFingerprint getFingerprint() {
         return getSubkeyFingerprint();
     }
 
@@ -81,12 +81,12 @@ public class SubkeyIdentifier {
     }
 
     /**
-     * Return the {@link OpenPgpV4Fingerprint} of the primary key of the identified key.
+     * Return the {@link OpenPgpFingerprint} of the primary key of the identified key.
      * This might be the same as {@link #getSubkeyFingerprint()} if the identified subkey is the primary key.
      *
      * @return primary key fingerprint
      */
-    public @Nonnull OpenPgpV4Fingerprint getPrimaryKeyFingerprint() {
+    public @Nonnull OpenPgpFingerprint getPrimaryKeyFingerprint() {
         return primaryKeyFingerprint;
     }
 
@@ -101,11 +101,11 @@ public class SubkeyIdentifier {
     }
 
     /**
-     * Return the {@link OpenPgpV4Fingerprint} of the identified subkey.
+     * Return the {@link OpenPgpFingerprint} of the identified subkey.
      *
      * @return subkey fingerprint
      */
-    public @Nonnull OpenPgpV4Fingerprint getSubkeyFingerprint() {
+    public @Nonnull OpenPgpFingerprint getSubkeyFingerprint() {
         return subkeyFingerprint;
     }
 
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 f5a23ca0..55b0fd8d 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
@@ -37,7 +37,7 @@ import org.pgpainless.algorithm.KeyFlag;
 import org.pgpainless.algorithm.PublicKeyAlgorithm;
 import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import org.pgpainless.exception.KeyValidationError;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.SubkeyIdentifier;
 import org.pgpainless.policy.Policy;
 import org.pgpainless.signature.SignaturePicker;
@@ -100,7 +100,7 @@ public class KeyRingInfo {
      * @param fingerprint fingerprint
      * @return public key or null
      */
-    public @Nullable PGPPublicKey getPublicKey(OpenPgpV4Fingerprint fingerprint) {
+    public @Nullable PGPPublicKey getPublicKey(OpenPgpFingerprint fingerprint) {
         return getPublicKey(fingerprint.getKeyId());
     }
 
@@ -201,7 +201,7 @@ public class KeyRingInfo {
      * @param fingerprint fingerprint
      * @return secret key or null
      */
-    public @Nullable PGPSecretKey getSecretKey(OpenPgpV4Fingerprint fingerprint) {
+    public @Nullable PGPSecretKey getSecretKey(OpenPgpFingerprint fingerprint) {
         return getSecretKey(fingerprint.getKeyId());
     }
 
@@ -244,12 +244,12 @@ public class KeyRingInfo {
     }
 
     /**
-     * Return the {@link OpenPgpV4Fingerprint} of this key ring.
+     * Return the {@link OpenPgpFingerprint} of this key ring.
      *
      * @return fingerprint
      */
-    public OpenPgpV4Fingerprint getFingerprint() {
-        return new OpenPgpV4Fingerprint(getPublicKey());
+    public OpenPgpFingerprint getFingerprint() {
+        return OpenPgpFingerprint.of(getPublicKey());
     }
 
     /**
@@ -603,7 +603,7 @@ public class KeyRingInfo {
      * @param fingerprint subkey fingerprint
      * @return expiration date or null
      */
-    public @Nullable Date getSubkeyExpirationDate(OpenPgpV4Fingerprint fingerprint) {
+    public @Nullable Date getSubkeyExpirationDate(OpenPgpFingerprint fingerprint) {
         if (getPublicKey().getKeyID() == fingerprint.getKeyId()) {
             return getPrimaryKeyExpirationDate();
         }
@@ -646,7 +646,7 @@ public class KeyRingInfo {
         }
 
         for (PGPPublicKey key : keysWithFlag) {
-            Date subkeyExpirationDate = getSubkeyExpirationDate(new OpenPgpV4Fingerprint(key));
+            Date subkeyExpirationDate = getSubkeyExpirationDate(OpenPgpFingerprint.of(key));
             if (subkeyExpirationDate == null) {
                 nonExpiringSubkeys.add(key);
             } else {
@@ -756,7 +756,7 @@ public class KeyRingInfo {
                 continue;
             }
 
-            Date subkeyExpiration = getSubkeyExpirationDate(new OpenPgpV4Fingerprint(subKey));
+            Date subkeyExpiration = getSubkeyExpirationDate(OpenPgpFingerprint.of(subKey));
             if (subkeyExpiration != null && subkeyExpiration.before(new Date())) {
                 continue;
             }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java b/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java
index 2785202c..27e6046b 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java
@@ -40,7 +40,7 @@ import org.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.algorithm.SignatureType;
 import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import org.pgpainless.implementation.ImplementationFactory;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.generation.KeyRingBuilder;
 import org.pgpainless.key.generation.KeySpec;
 import org.pgpainless.key.protection.CachingSecretKeyRingProtector;
@@ -214,7 +214,7 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
     }
 
     @Override
-    public SecretKeyRingEditorInterface deleteSubKey(OpenPgpV4Fingerprint fingerprint,
+    public SecretKeyRingEditorInterface deleteSubKey(OpenPgpFingerprint fingerprint,
                                                      SecretKeyRingProtector protector) {
         return deleteSubKey(fingerprint.getKeyId(), protector);
     }
@@ -244,7 +244,7 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
     }
 
     @Override
-    public SecretKeyRingEditorInterface revokeSubKey(OpenPgpV4Fingerprint fingerprint,
+    public SecretKeyRingEditorInterface revokeSubKey(OpenPgpFingerprint fingerprint,
                                                      SecretKeyRingProtector protector,
                                                      RevocationAttributes revocationAttributes)
             throws PGPException {
@@ -322,11 +322,11 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
     public SecretKeyRingEditorInterface setExpirationDate(Date expiration,
                                                           SecretKeyRingProtector secretKeyRingProtector)
             throws PGPException {
-        return setExpirationDate(new OpenPgpV4Fingerprint(secretKeyRing), expiration, secretKeyRingProtector);
+        return setExpirationDate(OpenPgpFingerprint.of(secretKeyRing), expiration, secretKeyRingProtector);
     }
 
     @Override
-    public SecretKeyRingEditorInterface setExpirationDate(OpenPgpV4Fingerprint fingerprint,
+    public SecretKeyRingEditorInterface setExpirationDate(OpenPgpFingerprint fingerprint,
                                                           Date expiration,
                                                           SecretKeyRingProtector secretKeyRingProtector)
             throws PGPException {
@@ -415,7 +415,7 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
                 }
             }
             if (oldSignature == null) {
-                throw new IllegalStateException("Key " + new OpenPgpV4Fingerprint(subjectPubKey) + " does not have a previous positive/casual/generic certification signature.");
+                throw new IllegalStateException("Key " + OpenPgpFingerprint.of(subjectPubKey) + " does not have a previous positive/casual/generic certification signature.");
             }
         } else {
             Iterator<PGPSignature> bindingSignatures = subjectPubKey.getSignaturesOfType(SignatureType.SUBKEY_BINDING.getCode());
@@ -425,7 +425,7 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
         }
 
         if (oldSignature == null) {
-            throw new IllegalStateException("Key " + new OpenPgpV4Fingerprint(subjectPubKey) + " does not have a previous subkey binding signature.");
+            throw new IllegalStateException("Key " + OpenPgpFingerprint.of(subjectPubKey) + " does not have a previous subkey binding signature.");
         }
         return oldSignature;
     }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.java b/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.java
index 5b8f329f..fc78f95c 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.java
@@ -15,7 +15,7 @@ import org.bouncycastle.openpgp.PGPSecretKey;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.bouncycastle.openpgp.PGPSignature;
 import org.bouncycastle.openpgp.PGPSignatureSubpacketVector;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.generation.KeySpec;
 import org.pgpainless.key.protection.KeyRingProtectionSettings;
 import org.pgpainless.key.protection.SecretKeyRingProtector;
@@ -104,7 +104,7 @@ public interface SecretKeyRingEditorInterface {
      * @param secretKeyRingProtector protector to unlock the secret key ring
      * @return the builder
      */
-    SecretKeyRingEditorInterface deleteSubKey(OpenPgpV4Fingerprint fingerprint, SecretKeyRingProtector secretKeyRingProtector);
+    SecretKeyRingEditorInterface deleteSubKey(OpenPgpFingerprint fingerprint, SecretKeyRingProtector secretKeyRingProtector);
 
     /**
      * Delete a subkey from the key ring.
@@ -150,7 +150,7 @@ public interface SecretKeyRingEditorInterface {
      * @param secretKeyRingProtector protector to unlock the secret key ring
      * @return the builder
      */
-    default SecretKeyRingEditorInterface revokeSubKey(OpenPgpV4Fingerprint fingerprint,
+    default SecretKeyRingEditorInterface revokeSubKey(OpenPgpFingerprint fingerprint,
                                                       SecretKeyRingProtector secretKeyRingProtector)
             throws PGPException {
         return revokeSubKey(fingerprint, secretKeyRingProtector, null);
@@ -166,7 +166,7 @@ public interface SecretKeyRingEditorInterface {
      * @param revocationAttributes reason for the revocation
      * @return the builder
      */
-    SecretKeyRingEditorInterface revokeSubKey(OpenPgpV4Fingerprint fingerprint,
+    SecretKeyRingEditorInterface revokeSubKey(OpenPgpFingerprint fingerprint,
                                               SecretKeyRingProtector secretKeyRingProtector,
                                               RevocationAttributes revocationAttributes)
             throws PGPException;
@@ -249,7 +249,7 @@ public interface SecretKeyRingEditorInterface {
      * @param secretKeyRingProtector protector to unlock the priary key
      * @return the builder
      */
-    SecretKeyRingEditorInterface setExpirationDate(OpenPgpV4Fingerprint fingerprint,
+    SecretKeyRingEditorInterface setExpirationDate(OpenPgpFingerprint fingerprint,
                                                    Date expiration,
                                                    SecretKeyRingProtector secretKeyRingProtector)
             throws PGPException;
@@ -270,7 +270,7 @@ public interface SecretKeyRingEditorInterface {
                                              RevocationAttributes revocationAttributes)
         throws PGPException;
 
-    default PGPSignature createRevocationCertificate(OpenPgpV4Fingerprint subkeyFingerprint,
+    default PGPSignature createRevocationCertificate(OpenPgpFingerprint subkeyFingerprint,
                                              SecretKeyRingProtector secretKeyRingProtector,
                                              RevocationAttributes revocationAttributes)
         throws PGPException {
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/protection/CachingSecretKeyRingProtector.java b/pgpainless-core/src/main/java/org/pgpainless/key/protection/CachingSecretKeyRingProtector.java
index 192fb9f9..d0cdd59e 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/protection/CachingSecretKeyRingProtector.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/protection/CachingSecretKeyRingProtector.java
@@ -15,7 +15,7 @@ import org.bouncycastle.openpgp.PGPKeyRing;
 import org.bouncycastle.openpgp.PGPPublicKey;
 import org.bouncycastle.openpgp.operator.PBESecretKeyDecryptor;
 import org.bouncycastle.openpgp.operator.PBESecretKeyEncryptor;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.protection.passphrase_provider.SecretKeyPassphraseProvider;
 import org.pgpainless.util.Passphrase;
 
@@ -84,7 +84,7 @@ public class CachingSecretKeyRingProtector implements SecretKeyRingProtector, Se
         addPassphrase(key.getKeyID(), passphrase);
     }
 
-    public void addPassphrase(@Nonnull OpenPgpV4Fingerprint fingerprint, @Nullable Passphrase passphrase) {
+    public void addPassphrase(@Nonnull OpenPgpFingerprint fingerprint, @Nullable Passphrase passphrase) {
         addPassphrase(fingerprint.getKeyId(), passphrase);
     }
 
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/DetachedSignatureCheck.java b/pgpainless-core/src/main/java/org/pgpainless/signature/DetachedSignatureCheck.java
index ab481b72..2ffcff0e 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/DetachedSignatureCheck.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/DetachedSignatureCheck.java
@@ -6,7 +6,7 @@ package org.pgpainless.signature;
 
 import org.bouncycastle.openpgp.PGPKeyRing;
 import org.bouncycastle.openpgp.PGPSignature;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.SubkeyIdentifier;
 
 /**
@@ -59,13 +59,13 @@ public class DetachedSignatureCheck {
     }
 
     /**
-     * Return the {@link OpenPgpV4Fingerprint} of the key that created the signature.
+     * Return the {@link OpenPgpFingerprint} of the key that created the signature.
      *
      * @return fingerprint of the signing key
      * @deprecated use {@link #getSigningKeyIdentifier()} instead.
      */
     @Deprecated
-    public OpenPgpV4Fingerprint getFingerprint() {
+    public OpenPgpFingerprint getFingerprint() {
         return signingKeyIdentifier.getSubkeyFingerprint();
     }
 }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/OnePassSignatureCheck.java b/pgpainless-core/src/main/java/org/pgpainless/signature/OnePassSignatureCheck.java
index 4fcfe239..ec22b6ab 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/OnePassSignatureCheck.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/OnePassSignatureCheck.java
@@ -7,7 +7,6 @@ package org.pgpainless.signature;
 import org.bouncycastle.openpgp.PGPOnePassSignature;
 import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPSignature;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
 import org.pgpainless.key.SubkeyIdentifier;
 
 /**
@@ -45,7 +44,7 @@ public class OnePassSignatureCheck {
     }
 
     /**
-     * Return the {@link OpenPgpV4Fingerprint} of the signing key.
+     * Return an identifier for the signing key.
      *
      * @return signing key fingerprint
      */
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureUtils.java b/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureUtils.java
index 754f3e7e..c4468b89 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureUtils.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureUtils.java
@@ -33,7 +33,7 @@ import org.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.algorithm.SignatureType;
 import org.pgpainless.algorithm.negotiation.HashAlgorithmNegotiator;
 import org.pgpainless.implementation.ImplementationFactory;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.util.OpenPgpKeyAttributeUtil;
 import org.pgpainless.key.util.RevocationAttributes;
 import org.pgpainless.signature.subpackets.SignatureSubpacketsUtil;
@@ -286,8 +286,14 @@ public final class SignatureUtils {
      * @return signatures issuing key id
      */
     public static long determineIssuerKeyId(PGPSignature signature) {
+        if (signature.getVersion() == 3) {
+            // V3 sigs do not contain subpackets
+            return signature.getKeyID();
+        }
+
         IssuerKeyID issuerKeyId = SignatureSubpacketsUtil.getIssuerKeyId(signature);
-        OpenPgpV4Fingerprint fingerprint = SignatureSubpacketsUtil.getIssuerFingerprintAsOpenPgpV4Fingerprint(signature);
+        OpenPgpFingerprint fingerprint = SignatureSubpacketsUtil.getIssuerFingerprintAsOpenPgpFingerprint(signature);
+
         if (issuerKeyId != null && issuerKeyId.getKeyID() != 0) {
             return issuerKeyId.getKeyID();
         }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureValidator.java b/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureValidator.java
index 69a7a80a..0a4947af 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureValidator.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/SignatureValidator.java
@@ -28,7 +28,7 @@ import org.pgpainless.algorithm.SignatureSubpacket;
 import org.pgpainless.algorithm.SignatureType;
 import org.pgpainless.exception.SignatureValidationException;
 import org.pgpainless.implementation.ImplementationFactory;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.policy.Policy;
 import org.pgpainless.signature.subpackets.SignatureSubpacketsUtil;
 import org.pgpainless.util.BCUtil;
@@ -57,7 +57,7 @@ public abstract class SignatureValidator {
         return new SignatureValidator() {
             @Override
             public void verify(PGPSignature signature) throws SignatureValidationException {
-                OpenPgpV4Fingerprint signingKeyFingerprint = new OpenPgpV4Fingerprint(signingKey);
+                OpenPgpFingerprint signingKeyFingerprint = OpenPgpFingerprint.of(signingKey);
 
                 Long issuer = SignatureSubpacketsUtil.getIssuerKeyIdAsLong(signature);
                 if (issuer != null) {
@@ -66,7 +66,7 @@ public abstract class SignatureValidator {
                     }
                 }
 
-                OpenPgpV4Fingerprint fingerprint = SignatureSubpacketsUtil.getIssuerFingerprintAsOpenPgpV4Fingerprint(signature);
+                OpenPgpFingerprint fingerprint = SignatureSubpacketsUtil.getIssuerFingerprintAsOpenPgpFingerprint(signature);
                 if (fingerprint != null) {
                     if (!fingerprint.equals(signingKeyFingerprint)) {
                         throw new SignatureValidationException("Signature was not created by " + signingKeyFingerprint + " (signature fingerprint: " + fingerprint + ")");
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketsUtil.java b/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketsUtil.java
index 226be119..4792a362 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketsUtil.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketsUtil.java
@@ -43,6 +43,7 @@ import org.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.algorithm.KeyFlag;
 import org.pgpainless.algorithm.SignatureSubpacket;
 import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
+import org.pgpainless.key.OpenPgpFingerprint;
 import org.pgpainless.key.OpenPgpV4Fingerprint;
 import org.pgpainless.signature.SignatureUtils;
 
@@ -71,23 +72,24 @@ public final class SignatureSubpacketsUtil {
     }
 
     /**
-     * Return the {@link IssuerFingerprint} subpacket of the signature into a {@link OpenPgpV4Fingerprint}.
+     * Return the {@link IssuerFingerprint} subpacket of the signature into a {@link org.pgpainless.key.OpenPgpFingerprint}.
      * If no v4 issuer fingerprint is present in the signature, return null.
      *
      * @param signature signature
      * @return v4 fingerprint of the issuer, or null
      */
-    public static OpenPgpV4Fingerprint getIssuerFingerprintAsOpenPgpV4Fingerprint(PGPSignature signature) {
+    public static OpenPgpFingerprint getIssuerFingerprintAsOpenPgpFingerprint(PGPSignature signature) {
         IssuerFingerprint subpacket = getIssuerFingerprint(signature);
         if (subpacket == null) {
             return null;
         }
 
+        OpenPgpFingerprint fingerprint = null;
         if (subpacket.getKeyVersion() == 4) {
-            OpenPgpV4Fingerprint fingerprint = new OpenPgpV4Fingerprint(Hex.encode(subpacket.getFingerprint()));
-            return fingerprint;
+            fingerprint = new OpenPgpV4Fingerprint(Hex.encode(subpacket.getFingerprint()));
         }
-        return null;
+
+        return fingerprint;
     }
 
     /**
diff --git a/pgpainless-core/src/main/java/org/pgpainless/util/ArmorUtils.java b/pgpainless-core/src/main/java/org/pgpainless/util/ArmorUtils.java
index f94a4ce3..41aac842 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/util/ArmorUtils.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/util/ArmorUtils.java
@@ -26,7 +26,7 @@ import org.bouncycastle.openpgp.PGPUtil;
 import org.bouncycastle.openpgp.operator.KeyFingerPrintCalculator;
 import org.bouncycastle.util.io.Streams;
 import org.pgpainless.algorithm.HashAlgorithm;
-import org.pgpainless.key.OpenPgpV4Fingerprint;
+import org.pgpainless.key.OpenPgpFingerprint;
 
 public final class ArmorUtils {
 
@@ -96,7 +96,7 @@ public final class ArmorUtils {
 
     private static MultiMap<String, String> keyToHeader(PGPKeyRing keyRing) {
         MultiMap<String, String> header = new MultiMap<>();
-        OpenPgpV4Fingerprint fingerprint = new OpenPgpV4Fingerprint(keyRing);
+        OpenPgpFingerprint fingerprint = OpenPgpFingerprint.of(keyRing);
         Iterator<String> userIds = keyRing.getPublicKey().getUserIDs();
 
         header.put(HEADER_COMMENT, fingerprint.prettyPrint());
diff --git a/pgpainless-core/src/test/java/org/pgpainless/signature/SignatureStructureTest.java b/pgpainless-core/src/test/java/org/pgpainless/signature/SignatureStructureTest.java
index 14d57567..84eecdb5 100644
--- a/pgpainless-core/src/test/java/org/pgpainless/signature/SignatureStructureTest.java
+++ b/pgpainless-core/src/test/java/org/pgpainless/signature/SignatureStructureTest.java
@@ -75,7 +75,7 @@ public class SignatureStructureTest {
     @Test
     public void testGetIssuerFingerprint() {
         assertEquals(new OpenPgpV4Fingerprint("D1A66E1A23B182C9980F788CFBFCC82A015E7330"),
-                SignatureSubpacketsUtil.getIssuerFingerprintAsOpenPgpV4Fingerprint(signature));
+                SignatureSubpacketsUtil.getIssuerFingerprintAsOpenPgpFingerprint(signature));
     }
 
     @Test