Added Encryptor interface for symmetric encryption esp. targeting SealedObject

- This will allow a keystore to be checked in (.keystore) and specified by installer
   - Algorithm parameters embedded in SealedObject but also supported by other Cipher methods
   ALF-8646: RINF 38: Text data encryption
   ALF-8956: RINF 38: Encryption key password specified by installer
   ALF-9055: RINF 38: Support encryption against existing data


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@28438 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/security/encryption/KeyProvider.java

@@ -3,11 +3,37 @@ package org.alfresco.repo.security.encryption;
 import java.security.Key;
 
 /**
- * A key provider returns the secret key used to encrypt text and mltext properties in the
- * database.
- *
+ * A key provider returns the secret keys for different use cases.
+ * 
+ * @since 4.0
  */
 public interface KeyProvider
 {
-    public Key getKey();
+    /**
+     * Enumeration of key aliases supported internally by Alfresco
+     * 
+     * @author derekh
+     * @since 4.0
+     */
+    public static enum AlfrescoKeyAlias
+    {
+        METADATA,
+        SOLR
+    }
+    
+    /**
+     * Get an encryption key if available.
+     * 
+     * @param keyAlias          the key alias
+     * @return                  the encryption key or <tt>null</tt> if there is no associated key
+     */
+    public Key getKey(String keyAlias);
+    
+    /**
+     * Get an encryption key if available, using a convenience constant.
+     * 
+     * @param keyAlias          the key alias
+     * @return                  the encryption key or <tt>null</tt> if there is no associated key
+     */
+    public Key getKey(AlfrescoKeyAlias keyAlias);
 }