From 8e2ad9323311958a4e8161c011b6187980bdb104 Mon Sep 17 00:00:00 2001
From: Sameera <sameira@gmail.com>
Date: Mon, 14 Nov 2016 22:31:50 +0530
Subject: [PATCH] Adding SHA-256 hashing impl and test classes

---
 core-java/pom.xml                             |  5 ++
 .../com/baeldung/hashing/SHA256Hashing.java   | 51 +++++++++++++++++++
 .../baeldung/hashing/SHA256HashingTest.java   | 37 ++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 core-java/src/main/java/com/baeldung/hashing/SHA256Hashing.java
 create mode 100644 core-java/src/test/java/com/baeldung/hashing/SHA256HashingTest.java

diff --git a/core-java/pom.xml b/core-java/pom.xml
index 8b93e238eb..17d9c2ce64 100644
--- a/core-java/pom.xml
+++ b/core-java/pom.xml
@@ -46,6 +46,11 @@
 			<version>3.3</version>
 		</dependency>
 
+		<dependency>
+			<groupId>org.bouncycastle</groupId>
+			<artifactId>bcprov-jdk15on</artifactId>
+			<version>1.55</version>
+		</dependency>
 		<!-- web -->
 
 		<!-- marshalling -->
diff --git a/core-java/src/main/java/com/baeldung/hashing/SHA256Hashing.java b/core-java/src/main/java/com/baeldung/hashing/SHA256Hashing.java
new file mode 100644
index 0000000000..9c8fc86e7a
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/hashing/SHA256Hashing.java
@@ -0,0 +1,51 @@
+package com.baeldung.hashing;
+
+
+import com.google.common.hash.Hashing;
+import org.apache.commons.codec.digest.DigestUtils;
+import org.bouncycastle.util.encoders.Hex;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class SHA256Hashing {
+
+    public static String HashWithJavaMessageDigest(final String originalString)
+            throws NoSuchAlgorithmException {
+        final MessageDigest digest = MessageDigest.getInstance("SHA-256");
+        final byte[] encodedhash = digest.digest(
+                originalString.getBytes(StandardCharsets.UTF_8));
+        return bytesToHex(encodedhash);
+    }
+
+    public static String HashWithGuava(final String originalString) {
+        final String sha256hex = Hashing.sha256().hashString(
+                originalString, StandardCharsets.UTF_8).toString();
+        return sha256hex;
+    }
+
+    public static String HashWithApacheCommons(final String originalString) {
+        final String sha256hex = DigestUtils.sha256Hex(originalString);
+        return sha256hex;
+    }
+
+    public static String HashWithBouncyCastle(final String originalString)
+            throws NoSuchAlgorithmException {
+        final MessageDigest digest = MessageDigest.getInstance("SHA-256");
+        final byte[] hash = digest.digest(
+                originalString.getBytes(StandardCharsets.UTF_8));
+        final String sha256hex = new String(Hex.encode(hash));
+        return sha256hex;
+    }
+
+    private static String bytesToHex(byte[] hash) {
+        StringBuffer hexString = new StringBuffer();
+        for (int i = 0; i < hash.length; i++) {
+            String hex = Integer.toHexString(0xff & hash[i]);
+            if(hex.length() == 1) hexString.append('0');
+            hexString.append(hex);
+        }
+        return hexString.toString();
+    }
+}
diff --git a/core-java/src/test/java/com/baeldung/hashing/SHA256HashingTest.java b/core-java/src/test/java/com/baeldung/hashing/SHA256HashingTest.java
new file mode 100644
index 0000000000..dc496d589b
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/hashing/SHA256HashingTest.java
@@ -0,0 +1,37 @@
+package com.baeldung.hashing;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+
+public class SHA256HashingTest {
+
+    private static String originalValue = "abc123";
+    private static String hashedValue =
+            "6ca13d52ca70c883e0f0bb101e425a89e8624de51db2d2392593af6a84118090";
+
+    @Test
+    public void testHashWithJavaMessageDigest() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithJavaMessageDigest(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+
+    @Test
+    public void testHashWithGuava() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithApacheCommons(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+
+    @Test
+    public void testHashWithApacheCommans() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithGuava(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+
+    @Test
+    public void testHashWithBouncyCastle() throws Exception {
+        final String currentHashedValue = SHA256Hashing.HashWithBouncyCastle(originalValue);
+        assertEquals(currentHashedValue, hashedValue);
+    }
+}
\ No newline at end of file