Allow custom key creation dates during generation

pgpainless-core/src/main/java/org/pgpainless/key/generation/KeyRingBuilder.java

@@ -305,9 +305,11 @@ public class KeyRingBuilder implements KeyRingBuilderInterface<KeyRingBuilder> {
         // Create raw Key Pair
         KeyPair keyPair = certKeyGenerator.generateKeyPair();
 
+        Date keyCreationDate = spec.getKeyCreationDate() != null ? spec.getKeyCreationDate() : new Date();
+
         // Form PGP key pair
         PGPKeyPair pgpKeyPair = ImplementationFactory.getInstance()
-                .getPGPKeyPair(type.getAlgorithm(), keyPair, new Date());
+                .getPGPKeyPair(type.getAlgorithm(), keyPair, keyCreationDate);
         return pgpKeyPair;
     }
 }

pgpainless-core/src/main/java/org/pgpainless/key/generation/KeySpec.java

@@ -5,6 +5,7 @@
 package org.pgpainless.key.generation;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 import org.bouncycastle.openpgp.PGPSignatureSubpacketVector;
 import org.pgpainless.algorithm.KeyFlag;
@@ -12,18 +13,23 @@ import org.pgpainless.key.generation.type.KeyType;
 import org.pgpainless.signature.subpackets.SignatureSubpackets;
 import org.pgpainless.signature.subpackets.SignatureSubpacketsHelper;
 
+import java.util.Date;
+
 public class KeySpec {
 
     private final KeyType keyType;
     private final SignatureSubpackets subpacketGenerator;
     private final boolean inheritedSubPackets;
+    private final Date keyCreationDate;
 
     KeySpec(@Nonnull KeyType type,
             @Nonnull SignatureSubpackets subpacketGenerator,
-            boolean inheritedSubPackets) {
+            boolean inheritedSubPackets,
+            @Nullable Date keyCreationDate) {
         this.keyType = type;
         this.subpacketGenerator = subpacketGenerator;
         this.inheritedSubPackets = inheritedSubPackets;
+        this.keyCreationDate = keyCreationDate;
     }
 
     @Nonnull
@@ -45,6 +51,11 @@ public class KeySpec {
         return inheritedSubPackets;
     }
 
+    @Nullable
+    public Date getKeyCreationDate() {
+        return keyCreationDate;
+    }
+
     public static KeySpecBuilder getBuilder(KeyType type, KeyFlag flag, KeyFlag... flags) {
         return new KeySpecBuilder(type, flag, flags);
     }

pgpainless-core/src/main/java/org/pgpainless/key/generation/KeySpecBuilder.java

@@ -5,6 +5,7 @@
 package org.pgpainless.key.generation;
 
 import java.util.Arrays;
+import java.util.Date;
 import java.util.LinkedHashSet;
 import java.util.Set;
 import javax.annotation.Nonnull;
@@ -31,6 +32,7 @@ public class KeySpecBuilder implements KeySpecBuilderInterface {
     private Set<CompressionAlgorithm> preferredCompressionAlgorithms = algorithmSuite.getCompressionAlgorithms();
     private Set<HashAlgorithm> preferredHashAlgorithms = algorithmSuite.getHashAlgorithms();
     private Set<SymmetricKeyAlgorithm> preferredSymmetricAlgorithms = algorithmSuite.getSymmetricKeyAlgorithms();
+    private Date keyCreationDate;
 
     KeySpecBuilder(@Nonnull KeyType type, KeyFlag flag, KeyFlag... flags) {
         if (flag == null) {
@@ -66,6 +68,11 @@ public class KeySpecBuilder implements KeySpecBuilderInterface {
         return this;
     }
 
+    @Override
+    public KeySpecBuilder setKeyCreationDate(@Nonnull Date creationDate) {
+        this.keyCreationDate = creationDate;
+        return this;
+    }
 
     @Override
     public KeySpec build() {
@@ -75,6 +82,6 @@ public class KeySpecBuilder implements KeySpecBuilderInterface {
         this.hashedSubpackets.setPreferredSymmetricKeyAlgorithms(preferredSymmetricAlgorithms);
         this.hashedSubpackets.setFeatures(Feature.MODIFICATION_DETECTION);
 
-        return new KeySpec(type, (SignatureSubpackets) hashedSubpackets, false);
+        return new KeySpec(type, (SignatureSubpackets) hashedSubpackets, false, keyCreationDate);
     }
 }

pgpainless-core/src/main/java/org/pgpainless/key/generation/KeySpecBuilderInterface.java

@@ -10,6 +10,8 @@ import org.pgpainless.algorithm.CompressionAlgorithm;
 import org.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
 
+import java.util.Date;
+
 public interface KeySpecBuilderInterface {
 
     KeySpecBuilder overridePreferredCompressionAlgorithms(@Nonnull CompressionAlgorithm... compressionAlgorithms);
@@ -18,5 +20,7 @@ public interface KeySpecBuilderInterface {
 
     KeySpecBuilder overridePreferredSymmetricKeyAlgorithms(@Nonnull SymmetricKeyAlgorithm... preferredSymmetricKeyAlgorithms);
 
+    KeySpecBuilder setKeyCreationDate(@Nonnull Date creationDate);
+
     KeySpec build();
 }

pgpainless-core/src/test/java/org/pgpainless/key/generation/GenerateKeyWithCustomCreationDateTest.java

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.key.generation;
+
+import org.bouncycastle.openpgp.PGPException;
+import org.bouncycastle.openpgp.PGPPublicKey;
+import org.bouncycastle.openpgp.PGPSecretKey;
+import org.bouncycastle.openpgp.PGPSecretKeyRing;
+import org.junit.JUtils;
+import org.junit.jupiter.api.Test;
+import org.pgpainless.PGPainless;
+import org.pgpainless.algorithm.KeyFlag;
+import org.pgpainless.key.generation.type.KeyType;
+import org.pgpainless.key.generation.type.eddsa.EdDSACurve;
+import org.pgpainless.key.generation.type.xdh.XDHSpec;
+import org.pgpainless.util.DateUtil;
+
+import java.security.InvalidAlgorithmParameterException;
+import java.security.NoSuchAlgorithmException;
+import java.util.Date;
+import java.util.Iterator;
+
+public class GenerateKeyWithCustomCreationDateTest {
+
+    @Test
+    public void generateKeyWithCustomCreationDateTest()
+            throws PGPException, InvalidAlgorithmParameterException, NoSuchAlgorithmException {
+        Date creationDate = DateUtil.parseUTCDate("2018-06-11 14:12:09 UTC");
+        PGPSecretKeyRing secretKeys = PGPainless.buildKeyRing()
+                .addSubkey(KeySpec.getBuilder(KeyType.XDH(XDHSpec._X25519), KeyFlag.ENCRYPT_COMMS, KeyFlag.ENCRYPT_STORAGE))
+                .setPrimaryKey(KeySpec.getBuilder(KeyType.EDDSA(EdDSACurve._Ed25519), KeyFlag.CERTIFY_OTHER, KeyFlag.SIGN_DATA)
+                        .setKeyCreationDate(creationDate)) // primary key with custom creation time
+                .addUserId("Alice")
+                .build();
+
+        Iterator<PGPSecretKey> iterator = secretKeys.iterator();
+        PGPPublicKey primaryKey = iterator.next().getPublicKey();
+        PGPPublicKey subkey = iterator.next().getPublicKey();
+
+        JUtils.assertDateEquals(creationDate, primaryKey.getCreationTime());
+        // subkey has no creation date override, so it was generated "just now"
+        JUtils.assertDateNotEquals(creationDate, subkey.getCreationTime());
+    }
+}