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Polish Pbkdf2PasswordEncoder 

Fixes gh-2158
Fixes gh-51
This commit is contained in:
Rob Winch 2016-04-12 17:01:01 -05:00
parent 0ab7126e64
commit 95a3e30d9f
4 changed files with 152 additions and 43 deletions
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67
crypto/src/main/java/org/springframework/security/crypto/password/PBKDF2PasswordEncoder.java → crypto/src/main/java/org/springframework/security/crypto/password/Pbkdf2PasswordEncoder.java
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@ -20,9 +20,13 @@ import java.security.GeneralSecurityException;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import org.springframework.security.crypto.codec.Hex;
import org.springframework.security.crypto.codec.Utf8;
import org.springframework.security.crypto.keygen.BytesKeyGenerator;
import org.springframework.security.crypto.keygen.KeyGenerators;
import static org.springframework.security.crypto.util.EncodingUtils.concatenate;
import static org.springframework.security.crypto.util.EncodingUtils.subArray;
/**
* A {@code PasswordEncoder} implementation that uses PBKDF2 with a configurable number of
@ -33,11 +37,15 @@ import static org.springframework.security.crypto.util.EncodingUtils.concatenate
* The algorithm is invoked on the concatenated bytes of the salt, secret and password.
*
* @author Rob Worsnop
* @author Rob Winch
* @since 4.1
*/
public class PBKDF2PasswordEncoder extends AbstractPasswordEncoder {
public class Pbkdf2PasswordEncoder implements PasswordEncoder {
private static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";
private static final int DEFAULT_HASH_WIDTH = 160;
private static final int DEFAULT_ITERATIONS = 1024;
private static final int DEFAULT_HASH_WIDTH = 256;
private static final int DEFAULT_ITERATIONS = 185000;
private final BytesKeyGenerator saltGenerator = KeyGenerators.secureRandom();
private final byte[] secret;
private final int hashWidth;
@ -45,9 +53,11 @@ public class PBKDF2PasswordEncoder extends AbstractPasswordEncoder {
/**
* Constructs a PBKDF2 password encoder with no additional secret value. There will be
* 1024 iterations and a hash width of 160.
* 360000 iterations and a hash width of 160. The default is based upon aiming for .5
* seconds to validate the password when this class was added.. Users should tune
* password verification to their own systems.
*/
public PBKDF2PasswordEncoder() {
public Pbkdf2PasswordEncoder() {
this("");
}
@ -57,7 +67,7 @@ public class PBKDF2PasswordEncoder extends AbstractPasswordEncoder {
*
* @param secret the secret key used in the encoding process (should not be shared)
*/
public PBKDF2PasswordEncoder(CharSequence secret) {
public Pbkdf2PasswordEncoder(CharSequence secret) {
this(secret, DEFAULT_ITERATIONS, DEFAULT_HASH_WIDTH);
}
@ -65,18 +75,51 @@ public class PBKDF2PasswordEncoder extends AbstractPasswordEncoder {
* Constructs a standard password encoder with a secret value as well as iterations
* and hash.
*
* @param secret
* @param iterations
* @param hashWidth
* @param secret the secret
* @param iterations the number of iterations. Users should aim for taking about .5
* seconds on their own system.
* @param hashWidth the size of the hash
*/
public PBKDF2PasswordEncoder(CharSequence secret, int iterations, int hashWidth) {
public Pbkdf2PasswordEncoder(CharSequence secret, int iterations, int hashWidth) {
this.secret = Utf8.encode(secret);
this.iterations = iterations;
this.hashWidth = hashWidth;
}
@Override
protected byte[] encode(CharSequence rawPassword, byte[] salt) {
public String encode(CharSequence rawPassword) {
byte[] salt = this.saltGenerator.generateKey();
byte[] encoded = encodeAndConcatenate(rawPassword, salt);
return String.valueOf(Hex.encode(encoded));
}
@Override
public boolean matches(CharSequence rawPassword, String encodedPassword) {
byte[] digested = Hex.decode(encodedPassword);
byte[] salt = subArray(digested, 0, this.saltGenerator.getKeyLength());
return matches(digested, encodeAndConcatenate(rawPassword, salt));
}
private byte[] encodeAndConcatenate(CharSequence rawPassword, byte[] salt) {
return concatenate(salt, encode(rawPassword, salt));
}
/**
* Constant time comparison to prevent against timing attacks.
*/
private static boolean matches(byte[] expected, byte[] actual) {
if (expected.length != actual.length) {
return false;
}
int result = 0;
for (int i = 0; i < expected.length; i++) {
result |= expected[i] ^ actual[i];
}
return result == 0;
}
private byte[] encode(CharSequence rawPassword, byte[] salt) {
try {
PBEKeySpec spec = new PBEKeySpec(rawPassword.toString().toCharArray(),
concatenate(salt, this.secret), this.iterations, this.hashWidth);
@ -87,4 +130,4 @@ public class PBKDF2PasswordEncoder extends AbstractPasswordEncoder {
throw new IllegalStateException("Could not create hash", e);
}
}
}
}

31
crypto/src/test/java/org/springframework/security/crypto/password/PBKDF2PasswordEncoderTests.java
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@ -1,31 +0,0 @@
package org.springframework.security.crypto.password;
import org.junit.Test;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
public class PBKDF2PasswordEncoderTests {
private PBKDF2PasswordEncoder encoder = new PBKDF2PasswordEncoder("secret");
@Test
public void matches() {
String result = encoder.encode("password");
assertFalse(result.equals("password"));
assertTrue(encoder.matches("password", result));
}
@Test
public void matchesLengthChecked() {
String result = encoder.encode("password");
assertFalse(encoder.matches("password", result.substring(0,result.length()-2)));
}
@Test
public void notMatches() {
String result = encoder.encode("password");
assertFalse(encoder.matches("bogus", result));
}
}

83
crypto/src/test/java/org/springframework/security/crypto/password/Pbkdf2PasswordEncoderTests.java Normal file
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@ -0,0 +1,83 @@
/*
* Copyright 2002-2015 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.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.security.crypto.password;
import org.junit.Test;
import static org.assertj.core.api.Assertions.assertThat;
public class Pbkdf2PasswordEncoderTests {
private Pbkdf2PasswordEncoder encoder = new Pbkdf2PasswordEncoder("secret");
@Test
public void matches() {
String result = this.encoder.encode("password");
assertThat(result.equals("password")).isFalse();
assertThat(this.encoder.matches("password", result)).isTrue();
}
@Test
public void matchesLengthChecked() {
String result = this.encoder.encode("password");
assertThat(this.encoder.matches("password",
result.substring(0, result.length() - 2))).isFalse();
}
@Test
public void notMatches() {
String result = this.encoder.encode("password");
assertThat(this.encoder.matches("bogus", result)).isFalse();
}
@Test
public void encodeSamePasswordMultipleTimesDiffers() {
String password = "password";
String encodeFirst = this.encoder.encode(password);
String encodeSecond = this.encoder.encode(password);
assertThat(encodeFirst).isNotEqualTo(encodeSecond);
}
/**
* Used to find the iteration count that takes .5 seconds.
*/
public void findDefaultIterationCount() {
// warm up
run(180000, 10);
// find the default
run(165000, 10);
}
private void run(int iterations, int count) {
long HALF_SECOND = 500L;
long avg = 0;
while (avg < HALF_SECOND) {
iterations += 10000;
Pbkdf2PasswordEncoder encoder = new Pbkdf2PasswordEncoder("", iterations,
256);
String encoded = encoder.encode("password");
System.out.println("Trying " + iterations);
long start = System.currentTimeMillis();
for (int i = 0; i < count; i++) {
encoder.matches("password", encoded);
}
long end = System.currentTimeMillis();
long diff = end - start;
avg = diff / count;
System.out.println("Avgerage " + avg);
}
System.out.println("Iterations " + iterations);
}
}

14
docs/manual/src/docs/asciidoc/index.adoc
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@ -381,6 +381,7 @@ You can find the highlights below:
* <<csrf-cookie,CookieCsrfTokenRepository>> provides simple AngularJS & CSRF integration
* Added `ForwardAuthenticationFailureHandler` & `ForwardAuthenticationSuccessHandler`
* SCrypt support with `SCryptPasswordEncoder`
* PBKDF2 support with <<spring-security-crypto-passwordencoders,Pbkdf2PasswordEncoder>>
* Meta Annotation Support
** <<test-method-meta-annotations,Test Meta Annotations>>
** <<method-security-meta-annotations,Method Security Meta Annotations>>
@ -6401,6 +6402,19 @@ String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));
----
The `Pbkdf2PasswordEncoder` implementation uses PBKDF2 algorithm to hash the passwords.
In order to defeat password cracking PBKDF2 is a deliberately slow algorithm and should be tuned to take about .5 seconds to verify a password on your system.
[source,java]
----
// Create an encoder with all the defaults
Pbkdf2PasswordEncoder encoder = new Pbkdf2PasswordEncoder();
String result = encoder.encode("myPassword");
assertTrue(encoder.matches("myPassword", result));
----
[[concurrency]]
== Concurrency Support