From d0be53f0a14a4d81d0fe3cc1227e4afd95833f5f Mon Sep 17 00:00:00 2001
From: Mike Hearn <mike@plan99.net>
Date: Sun, 6 Oct 2013 17:14:18 +0200
Subject: [PATCH] HD wallets: Fix method names that refer to SHA256 instead of
 SHA512.

Resolves issue 449.
---
 .../com/google/bitcoin/crypto/HDKeyDerivation.java |  6 +++---
 .../java/com/google/bitcoin/crypto/HDUtils.java    | 14 +++++++-------
 .../com/google/bitcoin/crypto/HDUtilsTest.java     |  3 +--
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/core/src/main/java/com/google/bitcoin/crypto/HDKeyDerivation.java b/core/src/main/java/com/google/bitcoin/crypto/HDKeyDerivation.java
index 49b7c548..df979587 100644
--- a/core/src/main/java/com/google/bitcoin/crypto/HDKeyDerivation.java
+++ b/core/src/main/java/com/google/bitcoin/crypto/HDKeyDerivation.java
@@ -34,7 +34,7 @@ public final class HDKeyDerivation {
 
     private HDKeyDerivation() { }
 
-    private static final HMac MASTER_HMAC_SHA256 = HDUtils.createHmacSha256Digest("Bitcoin seed".getBytes());
+    private static final HMac MASTER_HMAC_SHA512 = HDUtils.createHmacSha512Digest("Bitcoin seed".getBytes());
 
     /**
      * Generates a new deterministic key from the given seed, which can be any arbitrary byte array. However resist
@@ -45,7 +45,7 @@ public final class HDKeyDerivation {
      */
     public static DeterministicKey createMasterPrivateKey(byte[] seed) throws HDDerivationException {
         // Calculate I = HMAC-SHA512(key="Bitcoin seed", msg=S)
-        byte[] i = HDUtils.hmacSha256(MASTER_HMAC_SHA256, seed);
+        byte[] i = HDUtils.hmacSha512(MASTER_HMAC_SHA512, seed);
         // Split I into two 32-byte sequences, Il and Ir.
         // Use Il as master secret key, and Ir as master chain code.
         checkState(i.length == 64, i.length);
@@ -108,7 +108,7 @@ public final class HDKeyDerivation {
             data.put(parentPublicKey);
         }
         data.putInt(childNumber.getI());
-        byte[] i = HDUtils.hmacSha256(parent.getChainCode(), data.array());
+        byte[] i = HDUtils.hmacSha512(parent.getChainCode(), data.array());
         assert i.length == 64 : i.length;
         byte[] il = Arrays.copyOfRange(i, 0, 32);
         byte[] chainCode = Arrays.copyOfRange(i, 32, 64);
diff --git a/core/src/main/java/com/google/bitcoin/crypto/HDUtils.java b/core/src/main/java/com/google/bitcoin/crypto/HDUtils.java
index 47754c3e..a8eff185 100644
--- a/core/src/main/java/com/google/bitcoin/crypto/HDUtils.java
+++ b/core/src/main/java/com/google/bitcoin/crypto/HDUtils.java
@@ -45,23 +45,23 @@ public final class HDUtils {
         ecParams = new ECDomainParameters(params.getCurve(), params.getG(), params.getN(), params.getH());
     }
 
-    static HMac createHmacSha256Digest(byte[] key) {
+    static HMac createHmacSha512Digest(byte[] key) {
         SHA512Digest digest = new SHA512Digest();
         HMac hMac = new HMac(digest);
         hMac.init(new KeyParameter(key));
         return hMac;
     }
 
-    static byte[] hmacSha256(HMac hmacSha256, byte[] input) {
-        hmacSha256.reset();
-        hmacSha256.update(input, 0, input.length);
+    static byte[] hmacSha512(HMac hmacSha512, byte[] input) {
+        hmacSha512.reset();
+        hmacSha512.update(input, 0, input.length);
         byte[] out = new byte[64];
-        hmacSha256.doFinal(out, 0);
+        hmacSha512.doFinal(out, 0);
         return out;
     }
 
-    public static byte[] hmacSha256(byte[] key, byte[] data) {
-        return hmacSha256(createHmacSha256Digest(key), data);
+    public static byte[] hmacSha512(byte[] key, byte[] data) {
+        return hmacSha512(createHmacSha512Digest(key), data);
     }
 
     static BigInteger toBigInteger(byte[] bytes) {
diff --git a/core/src/test/java/com/google/bitcoin/crypto/HDUtilsTest.java b/core/src/test/java/com/google/bitcoin/crypto/HDUtilsTest.java
index 09c73954..c4ab9bc3 100644
--- a/core/src/test/java/com/google/bitcoin/crypto/HDUtilsTest.java
+++ b/core/src/test/java/com/google/bitcoin/crypto/HDUtilsTest.java
@@ -1,6 +1,5 @@
 package com.google.bitcoin.crypto;
 
-import com.google.bitcoin.crypto.HDUtils;
 import org.junit.Assert;
 import org.junit.Test;
 import org.slf4j.Logger;
@@ -105,7 +104,7 @@ public class HDUtilsTest {
         };
 
         for (int i = 0; i < tv.length; i += 3) {
-            Assert.assertArrayEquals("Case " + i, getBytes(tv, i + 2), HDUtils.hmacSha256(getBytes(tv, i), getBytes(tv, i + 1)));
+            Assert.assertArrayEquals("Case " + i, getBytes(tv, i + 2), HDUtils.hmacSha512(getBytes(tv, i), getBytes(tv, i + 1)));
         }
     }