Added constructors to PrivateKey, PublicKey, SigningPrivateKey and

SigningPublicKey, which take a single String argument and construct
the object from the Base64 data in that string (where this data is
the product of a .toBase64() call on a prior instance).

core/java/src/net/i2p/data/PrivateKey.java

@@ -33,6 +33,16 @@ public class PrivateKey extends DataStructureImpl {
         setData(null);
     }
 
+    /** constructs from base64
+     * @param a string of base64 data (the output of .toBase64() called
+     * on a prior instance of PrivateKey
+     * @author aum
+     */
+    public PrivateKey(String base64Data) throws DataFormatException {
+        this();
+        fromBase64(base64Data);
+    }
+
     public byte[] getData() {
         return _data;
     }

core/java/src/net/i2p/data/PublicKey.java

@@ -32,6 +32,16 @@ public class PublicKey extends DataStructureImpl {
         setData(null);
     }
 
+    /** constructs from base64
+     * @param a string of base64 data (the output of .toBase64() called
+     * on a prior instance of PublicKey
+     * @author aum
+     */
+    public PublicKey(String base64Data)  throws DataFormatException {
+        this();
+        fromBase64(base64Data);
+    }
+
     public byte[] getData() {
         return _data;
     }

core/java/src/net/i2p/data/SigningPrivateKey.java

@@ -30,9 +30,19 @@ public class SigningPrivateKey extends DataStructureImpl {
 
     public final static int KEYSIZE_BYTES = 20;
 
-    public SigningPrivateKey() { this(null); }
+    public SigningPrivateKey() { this((byte[])null); }
     public SigningPrivateKey(byte data[]) { setData(data); }
 
+    /** constructs from base64
+     * @param a string of base64 data (the output of .toBase64() called
+     * on a prior instance of SigningPrivateKey
+     * @author aum
+     */
+    public SigningPrivateKey(String base64Data)  throws DataFormatException {
+        this();
+        fromBase64(base64Data);
+    }
+
     public byte[] getData() {
         return _data;
     }

core/java/src/net/i2p/data/SigningPublicKey.java

@@ -29,9 +29,19 @@ public class SigningPublicKey extends DataStructureImpl {
 
     public final static int KEYSIZE_BYTES = 128;
 
-    public SigningPublicKey() { this(null); }
+    public SigningPublicKey() { this((byte[])null); }
     public SigningPublicKey(byte data[]) { setData(data); }
 
+    /** constructs from base64
+     * @param a string of base64 data (the output of .toBase64() called
+     * on a prior instance of SigningPublicKey
+     * @author aum
+     */
+    public SigningPublicKey(String base64Data)  throws DataFormatException {
+        this();
+        fromBase64(base64Data);
+    }
+
     public byte[] getData() {
         return _data;
     }