From 4e039df446f6f9349dd0c89f19055c8429f2e3fd Mon Sep 17 00:00:00 2001
From: Sean Gilligan <sean@msgilligan.com>
Date: Tue, 12 Sep 2023 10:50:23 -0700
Subject: [PATCH] PBKDF2SHA512: make hLen a constant

---
 core/src/main/java/org/bitcoinj/crypto/PBKDF2SHA512.java | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/org/bitcoinj/crypto/PBKDF2SHA512.java b/core/src/main/java/org/bitcoinj/crypto/PBKDF2SHA512.java
index 94671e117..2a0e9eddc 100644
--- a/core/src/main/java/org/bitcoinj/crypto/PBKDF2SHA512.java
+++ b/core/src/main/java/org/bitcoinj/crypto/PBKDF2SHA512.java
@@ -37,16 +37,17 @@ import java.nio.charset.StandardCharsets;
  * @see <a href="https://cryptofreek.org/2012/11/29/pbkdf2-pure-java-implementation/">PBKDF2 – Pure Java Implementation by Cryptofreek</a>
  */
 public class PBKDF2SHA512 {
+    // Length of HMAC result
+    private static final int H_LEN = 64;
+
     public static byte[] derive(String P, String S, int c, int dkLen) {
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
 
         try {
-            int hLen = 64;          // Length of HMAC result
-
-            if (dkLen > ((Math.pow(2, 32)) - 1) * hLen) {
+            if (dkLen > ((Math.pow(2, 32)) - 1) * H_LEN) {
                 throw new IllegalArgumentException("derived key too long");
             } else {
-                int l = (int) Math.ceil((double) dkLen / (double) hLen);
+                int l = (int) Math.ceil((double) dkLen / (double) H_LEN);
                 // int r = dkLen - (l-1)*hLen;
 
                 for (int i = 1; i <= l; i++) {