Introduce UserId utility class

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

@@ -57,6 +57,7 @@ import org.pgpainless.key.collection.PGPKeyRing;
 import org.pgpainless.key.generation.type.KeyType;
 import org.pgpainless.key.generation.type.curve.EllipticCurve;
 import org.pgpainless.key.generation.type.length.RsaLength;
+import org.pgpainless.key.util.UserId;
 import org.pgpainless.provider.ProviderFactory;
 import org.pgpainless.util.Passphrase;
 
@@ -69,6 +70,11 @@ public class KeyRingBuilder implements KeyRingBuilderInterface {
     private Set<String> additionalUserIds = new LinkedHashSet<>();
     private Passphrase passphrase;
 
+    public PGPKeyRing simpleRsaKeyRing(@Nonnull UserId userId, @Nonnull RsaLength length)
+            throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+        return simpleRsaKeyRing(userId.toString(), length);
+    }
+
     /**
      * Creates a simple, unencrypted RSA KeyPair of length {@code length} with user-id {@code userId}.
      * The KeyPair consists of a single RSA master key which is used for signing, encryption and certification.
@@ -87,6 +93,11 @@ public class KeyRingBuilder implements KeyRingBuilderInterface {
         return simpleRsaKeyRing(userId, length, null);
     }
 
+    public PGPKeyRing simpleRsaKeyRing(@Nonnull UserId userId, @Nonnull RsaLength rsaLength, String password)
+            throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+        return simpleRsaKeyRing(userId.toString(), rsaLength, password);
+    }
+
     /**
      * Creates a simple RSA KeyPair of length {@code length} with user-id {@code userId}.
      * The KeyPair consists of a single RSA master key which is used for signing, encryption and certification.
@@ -117,6 +128,11 @@ public class KeyRingBuilder implements KeyRingBuilderInterface {
         }
     }
 
+    public PGPKeyRing simpleEcKeyRing(@Nonnull UserId userId)
+            throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+        return simpleEcKeyRing(userId.toString());
+    }
+
     /**
      * Creates an unencrypted key ring consisting of an ECDSA master key and an ECDH sub-key.
      * The ECDSA master key is used for signing messages and certifying the sub key.
@@ -135,6 +151,11 @@ public class KeyRingBuilder implements KeyRingBuilderInterface {
         return simpleEcKeyRing(userId, null);
     }
 
+    public PGPKeyRing simpleEcKeyRing(@Nonnull UserId userId, String password)
+            throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+        return simpleEcKeyRing(userId.toString(), password);
+    }
+
     /**
      * Creates a key ring consisting of an ECDSA master key and an ECDH sub-key.
      * The ECDSA master key is used for signing messages and certifying the sub key.

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

@@ -21,6 +21,7 @@ import java.security.NoSuchAlgorithmException;
 
 import org.bouncycastle.openpgp.PGPException;
 import org.pgpainless.key.collection.PGPKeyRing;
+import org.pgpainless.key.util.UserId;
 import org.pgpainless.util.Passphrase;
 
 public interface KeyRingBuilderInterface {
@@ -31,6 +32,10 @@ public interface KeyRingBuilderInterface {
 
     interface WithPrimaryUserId {
 
+        default WithAdditionalUserIdOrPassphrase withPrimaryUserId(@Nonnull UserId userId) {
+            return withPrimaryUserId(userId.toString());
+        }
+
         WithAdditionalUserIdOrPassphrase withPrimaryUserId(@Nonnull String userId);
 
         WithAdditionalUserIdOrPassphrase withPrimaryUserId(@Nonnull byte[] userId);
@@ -39,6 +44,10 @@ public interface KeyRingBuilderInterface {
 
     interface WithAdditionalUserIdOrPassphrase {
 
+        default WithAdditionalUserIdOrPassphrase withAdditionalUserId(@Nonnull UserId userId) {
+            return withAdditionalUserId(userId.toString());
+        }
+
         WithAdditionalUserIdOrPassphrase withAdditionalUserId(@Nonnull String userId);
 
         WithAdditionalUserIdOrPassphrase withAdditionalUserId(@Nonnull byte[] userId);

pgpainless-core/src/main/java/org/pgpainless/key/modification/KeyRingEditorInterface.java

@@ -27,10 +27,15 @@ import org.pgpainless.key.OpenPgpV4Fingerprint;
 import org.pgpainless.key.generation.KeySpec;
 import org.pgpainless.key.protection.KeyRingProtectionSettings;
 import org.pgpainless.key.protection.SecretKeyRingProtector;
+import org.pgpainless.key.util.UserId;
 import org.pgpainless.util.Passphrase;
 
 public interface KeyRingEditorInterface {
 
+    default KeyRingEditorInterface addUserId(UserId userId, SecretKeyRingProtector secretKeyRingProtector) throws PGPException {
+        return addUserId(userId.toString(), secretKeyRingProtector);
+    }
+
     /**
      * Add a user-id to the primary key of the key ring.
      *
@@ -39,10 +44,18 @@ public interface KeyRingEditorInterface {
      */
     KeyRingEditorInterface addUserId(String userId, SecretKeyRingProtector secretKeyRingProtector) throws PGPException;
 
+    default  KeyRingEditorInterface addUserId(OpenPgpV4Fingerprint fingerprint, UserId userId, SecretKeyRingProtector secretKeyRingProtector) throws PGPException {
+        return addUserId(fingerprint, userId.toString(), secretKeyRingProtector);
+    }
+
     default KeyRingEditorInterface addUserId(OpenPgpV4Fingerprint fingerprint, String userId, SecretKeyRingProtector secretKeyRingProtector) throws PGPException {
         return addUserId(fingerprint.getKeyId(), userId, secretKeyRingProtector);
     }
 
+    default KeyRingEditorInterface addUserId(long keyId, UserId userId, SecretKeyRingProtector secretKeyRingProtector) throws PGPException {
+        return addUserId(keyId, userId.toString(), secretKeyRingProtector);
+    }
+
     KeyRingEditorInterface addUserId(long keyId, String userId, SecretKeyRingProtector secretKeyRingProtector) throws PGPException;
 
     /**

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

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pgpainless.key.util;
+
+public class UserId implements CharSequence {
+
+    private final String name;
+    private final String comment;
+    private final String email;
+
+    public UserId(String name, String comment, String email) {
+        this.name = name;
+        this.comment = comment;
+        this.email = email;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        if (name != null) {
+            sb.append(name);
+        }
+        if (comment != null) {
+            sb.append(" (").append(comment).append(')');
+        }
+        if (email != null) {
+            sb.append(sb.length() != 0 ? " <" : '<').append(email).append('>');
+        }
+        return sb.toString();
+    }
+
+    public static UserId onlyEmail(String email) {
+        if (email == null) {
+            throw new IllegalArgumentException("Email must not be null.");
+        }
+        return new UserId(null, null, email);
+    }
+
+    public static WithComment withName(String name) {
+        if (name == null) {
+            throw new IllegalArgumentException("Name must not be null.");
+        }
+        return new WithComment(name);
+    }
+
+    public static class WithComment {
+
+        private final String name;
+
+        public WithComment(String name) {
+            this.name = name;
+        }
+
+        public WithEmail withComment(String comment) {
+            if (comment == null) {
+                throw new IllegalArgumentException("Comment must not be null.");
+            }
+            return new WithEmail(name, comment);
+        }
+
+        public WithEmail noComment() {
+            return new WithEmail(name, null);
+        }
+
+        public UserId build() {
+            return new UserId(name, null, null);
+        }
+    }
+
+    public static class WithEmail {
+
+        private final String name;
+        private final String comment;
+
+        public WithEmail(String name, String comment) {
+            this.name = name;
+            this.comment = comment;
+        }
+
+        public UserId withEmail(String email) {
+            if (email == null) {
+                throw new IllegalArgumentException("Email must not be null.");
+            }
+            return new UserId(name, comment, email);
+        }
+
+        public UserId noEmail() {
+            return new UserId(name, comment, null);
+        }
+    }
+
+
+    @Override
+    public int length() {
+        return toString().length();
+    }
+
+    @Override
+    public char charAt(int i) {
+        return toString().charAt(i);
+    }
+
+    @Override
+    public CharSequence subSequence(int i, int i1) {
+        return toString().subSequence(i, i1);
+    }
+
+}

pgpainless-core/src/test/java/org/pgpainless/key/UserIdTest.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pgpainless.key;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.pgpainless.key.util.UserId;
+
+public class UserIdTest {
+
+    @Test(expected = IllegalArgumentException.class)
+    public void throwForNullName() {
+        UserId.withName(null);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void throwForNullComment() {
+        UserId.withName("foo")
+                .withComment(null);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void throwForNullEmail() {
+        UserId.withName("foo")
+                .withComment("bar")
+                .withEmail(null);
+    }
+
+    @Test
+    public void testFormatOnlyName() {
+        assertEquals(
+                "Juliet Capulet",
+                UserId.withName("Juliet Capulet")
+                        .build().toString());
+    }
+
+    @Test
+    public void testFormatNameAndComment() {
+        assertEquals(
+                "Juliet Capulet (from the play)",
+                UserId.withName("Juliet Capulet")
+                        .withComment("from the play")
+                        .noEmail().toString());
+    }
+
+    @Test
+    public void testFormatNameCommentAndMail() {
+        assertEquals("Juliet Capulet (from the play) <juliet@capulet.lit>",
+                UserId.withName("Juliet Capulet")
+                        .withComment("from the play")
+                        .withEmail("juliet@capulet.lit")
+                        .toString());
+    }
+
+    @Test
+    public void testFormatNameAndEmail() {
+        assertEquals("Juliet Capulet <juliet@capulet.lit>",
+                UserId.withName("Juliet Capulet")
+                        .noComment()
+                        .withEmail("juliet@capulet.lit")
+                        .toString());
+    }
+}