Simplify Digester utility class.

core/src/main/java/org/springframework/security/crypto/password/Digester.java

@@ -22,12 +22,12 @@ import java.security.NoSuchProviderException;
 /**
  * Helper for working with the MessageDigest API.
  *
- * Performs 1024 iterations of the hashing algorithm per digest to aid in protecting against brute force attacks.
+ * Performs the configured number of iterations of the hashing algorithm per digest to aid in protecting against brute force attacks.
  *
  * @author Keith Donald
  * @author Luke Taylor
  */
-class Digester {
+final class Digester {
 
     private final MessageDigest messageDigest;
 
@@ -36,6 +36,7 @@ class Digester {
     /**
      * Create a new Digester.
      * @param algorithm the digest algorithm; for example, "SHA-1" or "SHA-256".
+     * @param iterations the number of times to apply the digest algorithm to the input
      */
     public Digester(String algorithm, int iterations) {
         try {
@@ -49,16 +50,10 @@ class Digester {
 
     public byte[] digest(byte[] value) {
         synchronized (messageDigest) {
-            for (int i = 0; i < (iterations - 1); i++) {
-                value = invokeDigest(value);
+            for (int i = 0; i < iterations; i++) {
+                value = messageDigest.digest(value);
             }
-            return messageDigest.digest(value);
+            return value;
         }
     }
-
-    private byte[] invokeDigest(byte[] value) {
-        messageDigest.reset();
-        return messageDigest.digest(value);
-    }
-
 }

core/src/test/java/org/springframework/security/crypto/password/DigesterTests.java

@@ -14,11 +14,11 @@ import org.springframework.security.crypto.password.Digester;
 public class DigesterTests {
 
     @Test
-    public void digestIsCorrectFor2Iterations() {
-        Digester digester = new Digester("SHA-1", 2);
+    public void digestIsCorrectFor3Iterations() {
+        Digester digester = new Digester("SHA-1", 3);
         byte[] result = digester.digest(Utf8.encode("text"));
-        // echo -n text | openssl sha1 -binary | openssl sha1
-        assertEquals("cdcefc6a573f294e60e1d633bca3aeba450954a3", new String(Hex.encode(result)));
+        // echo -n text | openssl sha1 -binary | openssl sha1 -binary | openssl sha1
+        assertEquals("3cfa28da425eca5b894f0af2b158adf7001e000f", new String(Hex.encode(result)));
     }
 
 }