[Java] パスワードをSHA-256でハッシュ化

PasswordHash.java

import org.apache.commons.codec.digest.DigestUtils;
public static String hash(String password, String salt) {
  return DigestUtils.sha256Hex(password + salt);
}

public static String hashAndStretch(String password, String salt, int count) {
  String hashed = password;
  for (int i = 0; i < count; i++) {
    hashed = hash(hashed, salt);
  }
  return hashed;
}

private static final String hash1 = hash("password1", "[email protected]");

@Test
public void testHashEqual() {
  String hashed = hash("password1", "[email protected]");
  assertTrue(hashed, hashed.matches("[0-9a-f]{64}"));
  assertTrue(hashed.equals(hash1));
  assertEquals("f3b89377204b8c312722982de07d5178086c2ba070e43a061b105d73982a1b5b", hashed);
}

@Test
public void testHashChangePassword() {
  String hashed = hash("password2", "[email protected]");
  assertTrue(hashed, hashed.matches("[0-9a-f]{64}"));
  assertFalse(hashed.equals(hash1));
}

@Test
public void testHashChangeSalt() {
  String hashed = hash("password1", "[email protected]");
  assertTrue(hashed, hashed.matches("[0-9a-f]{64}"));
  assertFalse(hashed.equals(hash1));
}

@Test
public void testHashAndStretch1() {
  String hashed = hashAndStretch("password1", "[email protected]", 1);
  assertTrue(hashed, hashed.matches("[0-9a-f]{64}"));
  assertTrue(hashed.equals(hash1));
}

@Test
public void testHashAndStretch1000() {
  String hashed = hashAndStretch("password1", "[email protected]", 1000);
  assertTrue(hashed, hashed.matches("[0-9a-f]{64}"));
  assertFalse(hashed.equals(hash1));
}