76 Provide an option to provide alias name for P12Generator (#77)

Provide an overloaded method to control the label of the keypair entry.

src/main/java/org/cryptacular/generator/AbstractP12Generator.java

@@ -32,8 +32,10 @@
 public abstract class AbstractP12Generator implements P12Generator
 {
   @Override
-  public PKCS12PfxPdu generate(final char[] password, final PrivateKey key, final X509Certificate... certificates)
+  public PKCS12PfxPdu generate(final char[] password, final PrivateKey key, final String alias,
+    final X509Certificate... certificates)
   {
+    String label;
     if (certificates.length < 1) {
       throw new IllegalArgumentException("At least one certificate must be provided");
     }
@@ -45,15 +47,14 @@ public PKCS12PfxPdu generate(final char[] password, final PrivateKey key, final
     final JcaX509ExtensionUtils extUtils;
     try {
       extUtils = new JcaX509ExtensionUtils();
-      String label = "end-entity-cert";
       final PKCS12SafeBagBuilder keyBagBuilder = new JcaPKCS12SafeBagBuilder(
         key, keyOutputEncryptor(password));
-      keyBagBuilder.addBagAttribute(PKCSObjectIdentifiers.pkcs_9_at_friendlyName, new DERBMPString(label));
+      keyBagBuilder.addBagAttribute(PKCSObjectIdentifiers.pkcs_9_at_friendlyName, new DERBMPString(alias));
       keyBagBuilder.addBagAttribute(
         PKCSObjectIdentifiers.pkcs_9_at_localKeyId,
         extUtils.createSubjectKeyIdentifier(certificates[0].getPublicKey()));
       certBags[0] = new JcaPKCS12SafeBagBuilder(certificates[0])
-        .addBagAttribute(PKCSObjectIdentifiers.pkcs_9_at_friendlyName, new DERBMPString(label))
+        .addBagAttribute(PKCSObjectIdentifiers.pkcs_9_at_friendlyName, new DERBMPString(alias))
         .addBagAttribute(
           PKCSObjectIdentifiers.pkcs_9_at_localKeyId,
           extUtils.createSubjectKeyIdentifier(certificates[0].getPublicKey()))
@@ -77,6 +78,11 @@ public PKCS12PfxPdu generate(final char[] password, final PrivateKey key, final
       throw new CryptoException("P12 generation failed", e);
     }
   }
+  @Override
+  public PKCS12PfxPdu generate(final char[] password, final PrivateKey key, final X509Certificate... certificates)
+  {
+    return generate(password, key, "end-entity-cert", certificates);
+  }
 
   /** @return Number of hashing rounds. */
   public abstract int getIterations();

src/main/java/org/cryptacular/generator/P12Generator.java

@@ -23,4 +23,17 @@ public interface P12Generator
    * @return Bouncy Castle PKCS12 container object.
    */
   PKCS12PfxPdu generate(char[] password, PrivateKey key, X509Certificate... certificates);
+
+  /**
+   * Generates a PKCS12 container object that contains the given private key and certificates with the given alias.
+   *
+   * @param password PKCS12 encryption password. This secret is also used to encrypt the inner private key.
+   * @param key Private key.
+   * @param alias Keystore alias.
+   * @param certificates One or more certificates. If more than one certificate is provided, the first is taken as the
+   *                     end-entity certificate.
+   *
+   * @return Bouncy Castle PKCS12 container object.
+   */
+  PKCS12PfxPdu generate(char[] password, PrivateKey key, String alias, X509Certificate... certificates);
 }