KeyCrypter: increase default for number of Scrypt iterations

Also update the recommendation in a comment.

Author: schildbach

core/src/main/java/org/bitcoinj/crypto/KeyCrypter.java

@@ -81,7 +81,7 @@ enum EncryptionType {
      * @see <a href="http://stackoverflow.com/questions/11126315/what-are-optimal-scrypt-work-factors">What are optimal scrypt work factors?</a>
      */
     class ScryptParameters {
-        public static final int DEFAULT_N = 16384;
+        public static final int DEFAULT_N = 131072;
         public static final int DEFAULT_R = 8;
         public static final int DEFAULT_P = 1;
         private final byte[] salt;

core/src/main/java/org/bitcoinj/crypto/KeyCrypterScrypt.java

@@ -94,7 +94,7 @@ public KeyCrypterScrypt() {
 
     /**
      * Encryption/Decryption using custom number of iterations parameters and a random salt.
-     * As of August 2016, a useful value for mobile devices is 4096 (derivation takes about 1 second).
+     * As of May 2026, a useful value for mobile devices is 131072 (derivation takes about 1 second).
      *
      * @param iterations
      *            number of scrypt iterations