javadoc, log, comment, and su3file help tweaks

core/java/src/net/i2p/crypto/SU3File.java

@@ -358,9 +358,9 @@ public class SU3File {
     }
 
     private static final void showUsageCLI() {
-        System.err.println("Usage: SU3File showversion   signedFile");
-        System.err.println("       SU3File sign          inputFile signedFile privateKeyFile version signerName");
-        System.err.println("       SU3File verifysig     signedFile");
+        System.err.println("Usage: SU3File showversion   signedFile.su3");
+        System.err.println("       SU3File sign          inputFile.zip signedFile.su3 privateKeyFile version signerName@mail.i2p");
+        System.err.println("       SU3File verifysig     signedFile.su3");
     }
 
     /** @return success */

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

@@ -13,6 +13,13 @@ package net.i2p.data;
  * Defines an end point in the I2P network.  The Destination may move around
  * in the network, but messages sent to the Destination will find it
  *
+ * Note that the public (encryption) key is essentially unused, since
+ * "end-to-end" encryption was removed in 0.6. The public key in the
+ * LeaseSet is used instead.
+ *
+ * The first bytes of the public key are used for the IV for leaseset encryption,
+ * but that encryption is poorly designed and should be deprecated.
+ *
  * @author jrandom
  */
 public class Destination extends KeysAndCert {

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

@@ -31,6 +31,10 @@ import net.i2p.util.RandomSource;
  * Only the gateways and tunnel IDs in the individual
  * leases are encrypted.
  *
+ * WARNING:
+ * Encryption is poorly designed and probably insecure.
+ * Not recommended.
+ *
  * Encrypted leases are not indicated as such.
  * The only way to tell a lease is encrypted is to
  * determine that the listed gateways do not exist.

core/java/src/net/i2p/util/RandomSource.java

@@ -176,8 +176,7 @@ public class RandomSource extends SecureRandom implements EntropyHarvester {
             SecureRandom.getInstance("SHA1PRNG").nextBytes(buf);
             ok = true;
         } catch (NoSuchAlgorithmException e) {}
-        // why urandom?  because /dev/random blocks, and there are arguments
-        // suggesting such blockages are largely meaningless
+        // why urandom?  because /dev/random blocks
         ok = seedFromFile(new File("/dev/urandom"), buf) || ok;
         // we merge (XOR) in the data from /dev/urandom with our own seedfile
         File localFile = new File(_context.getConfigDir(), SEEDFILE);
@@ -186,6 +185,8 @@ public class RandomSource extends SecureRandom implements EntropyHarvester {
     }
     
     /**
+     *  XORs the seed into buf
+     *
      *  @param f absolute path
      *  @return success
      */