Added the ability to customize the Provider which is used

to get an instance of MD5 and SHA.  By default, this
Utils class will search the list of available Provider objects
for implementations, but if you want to supply your own
Provider object you may do so by calling the static method
setProvider on DigestUtils. + Also, brought test coverage
of DigestUtils up to 100%


git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/codec/trunk@130210 13f79535-47bb-0310-9956-ffa450edef68

Author: Timothy O'Brien

src/java/org/apache/commons/codec/digest/DigestUtils.java

@@ -59,6 +59,8 @@
 
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
+import java.security.Provider;
+import java.security.Security;
 
 import org.apache.commons.codec.binary.Hex;
 
@@ -70,6 +72,13 @@
  * @author David Graham
  */
 public class DigestUtils {
+    
+    /**
+     * This is the provider which DigestUtils uses to get instances of the MD5 and SHA 
+     * algorithms.  This variable is altered if a users wishes to customize the implementation
+     * of an algorithm.
+     */
+    private static Provider provider = null;
 
 	/**
 	 * Returns an MD5 MessageDigest.
@@ -78,10 +87,13 @@ public class DigestUtils {
 	 */
 	private static MessageDigest getMd5Digest() {
 		try {
-			return MessageDigest.getInstance("MD5");
-
+            if( provider != null ) {
+    			return MessageDigest.getInstance("MD5", provider);
+            } else {
+                return MessageDigest.getInstance("MD5");
+            }
 		} catch (NoSuchAlgorithmException e) {
-			throw new InternalError(e.getMessage());
+			throw new RuntimeException("Unable to get instance of MD5 message digest in DigestUtils" + e.getMessage());
 		}
 	}
 
@@ -92,10 +104,13 @@ private static MessageDigest getMd5Digest() {
 	 */
 	private static MessageDigest getShaDigest() {
 		try {
-			return MessageDigest.getInstance("SHA");
-
+            if( provider != null) {
+                return MessageDigest.getInstance("SHA", provider);
+            } else {
+                return MessageDigest.getInstance("SHA");
+            }
 		} catch (NoSuchAlgorithmException e) {
-			throw new InternalError(e.getMessage());
+            throw new RuntimeException("Unable to get instance of SHA message digest in DigestUtils" + e.getMessage());
 		}
 	}
 
@@ -184,5 +199,14 @@ public static String shaHex(byte[] data) {
 	public static String shaHex(String data) {
 		return new String(Hex.encodeHex(sha(data)));
 	}
-
+    
+    /**
+     * Allows for the replacement of the default Provider from which the DigestUtils
+     * retrieves the implementations of MD5 and SHA.
+     * 
+     * @param provider an instance of a Provider
+     */
+    public static void setProvider(Provider pProvider) {
+        provider = pProvider;
+    }
 }

src/test/org/apache/commons/codec/digest/DigestUtilsTest.java

@@ -57,6 +57,12 @@
 
 package org.apache.commons.codec.digest;
 
+import java.security.MessageDigest;
+import java.security.MessageDigestSpi;
+import java.security.Security;
+
+import org.apache.commons.codec.EncoderException;
+
 import junit.framework.TestCase;
 
 /**
@@ -129,11 +135,38 @@ public void testShaHex() {
 			"a9993e364706816aba3e25717850c26c9cd0d89d",
 			DigestUtils.shaHex("abc"));
 
+        assertEquals(
+            "a9993e364706816aba3e25717850c26c9cd0d89d",
+            DigestUtils.shaHex("abc".getBytes()));
+
 		assertEquals(
 			"84983e441c3bd26ebaae4aa1f95129e5e54670f1",
 			DigestUtils.shaHex(
 				"abcdbcdecdefdefgefghfghighij"
 					+ "hijkijkljklmklmnlmnomnopnopq"));
 	}
-
+    
+    public void testMd5NoAvailable() {
+        DigestUtils.setProvider( Security.getProviders()[3]);
+
+        try {        
+            DigestUtils.md5("test");
+            fail( "The provider does not supply the MD5 algorithm, this operation should have failed");
+        } catch( RuntimeException re ) {
+            
+        }
+    
+    }
+
+    public void testSHANoAvailable() {
+        DigestUtils.setProvider( Security.getProviders()[3]);
+
+        try {        
+            DigestUtils.sha("test");
+            fail( "The provider does not supply the SHA algorithm, this operation should have failed");
+        } catch( RuntimeException re ) {
+            
+        }
+    
+    }
 }