SCryptPasswordEncoder to take default keyLength value

Fixes gh-4225
Closes gh-4231

crypto/src/main/java/org/springframework/security/crypto/scrypt/SCryptPasswordEncoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -163,7 +163,7 @@ public class SCryptPasswordEncoder implements PasswordEncoder {
 	}
 
 	private String digest(CharSequence rawPassword, byte[] salt) {
-		byte[] derived = SCrypt.generate(Utf8.encode(rawPassword), salt, cpuCost, memoryCost, parallelization, 32);
+		byte[] derived = SCrypt.generate(Utf8.encode(rawPassword), salt, cpuCost, memoryCost, parallelization, keyLength);
 
 		String params = Long
 				.toString(((int) (Math.log(cpuCost) / Math.log(2)) << 16L) | memoryCost << 8 | parallelization, 16);

crypto/src/test/java/org/springframework/security/crypto/scrypt/SCryptPasswordEncoderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -65,7 +65,7 @@ public class SCryptPasswordEncoderTests {
 
 	@Test
 	public void samePasswordWithDifferentParams() {
-		SCryptPasswordEncoder oldEncoder = new SCryptPasswordEncoder(512, 8, 4, 64, 16);
+		SCryptPasswordEncoder oldEncoder = new SCryptPasswordEncoder(16384, 8, 1, 32,64);
 		SCryptPasswordEncoder newEncoder = new SCryptPasswordEncoder();
 
 		String password = "secret";