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Negative Matching Rules

Unlike positive matching rules, negative matching rules reject passwords that contain provided characters, regular expressions, entries, etc.
Let's find out what are the negative matching rules:

• 
  IllegalCharacterRule – defines all characters that a password mustn't contain
  
• 
  IllegalRegexRule – defines a regular expression which mustn't match
  
• 
  IllegalSequenceRule – checks whether a password has an illegal sequence of characters
  
• 
  NumberRangeRule – defines a range of numbers which a password mustn't contain
  
• 
  WhitespaceRule – checks whether a password contains whitespaces
  
• 
  DictionaryRule – checks whether a password is equal to any dictionary record
  
• 
  DictionarySubstringRule – checks whether a password contain any dictionary record
  
• 
  HistoryRule – checks whether a password contains any historical password reference
  
• 
  DigestHistoryRule – checks whether a password contains any digested historical password reference
  
• 
  SourceRule – checks whether a password contains any source password reference
  
• 
  DigestSourceRule – checks whether a password contains any digest source password reference
  
• 
  UsernameRule – checks whether a password contains a username
  
• 
  RepeatCharacterRegexRule – checks whether a password contains repeated ASCII characters
  

6.1. Simple Negative Matching Rules

Firstly, we're going to see how we can use simple rules such as IllegalCharacterRule, IllegalRegexRule, etc. Here is a short example:

PasswordValidator passwordValidator = new PasswordValidator(
new IllegalCharacterRule(new char[] { 'a' }),
new NumberRangeRule(1, 10),
new WhitespaceRule()
);


RuleResult validate = passwordValidator.validate(new PasswordData("abcd22 "));


assertFalse(validate.isValid());
assertEquals(
"ILLEGAL_CHAR:{illegalCharacter=a, matchBehavior=contains}",
getDetail(validate, 0));
assertEquals(
"ILLEGAL_NUMBER_RANGE:{number=2, matchBehavior=contains}",
getDetail(validate, 4));
assertEquals(
"ILLEGAL_WHITESPACE:{whitespaceCharacter= , matchBehavior=contains}",
getDetail(validate, 5));

The example shows us how the described rules work. Similarly to positive matching rules, they give us full feedback about validation.

6.2. Dictionary Rules
What if we want to check whether a password is not equal to provided words.
For that reason, the Passay library gives us excellent tools for that. Let's discover DictionaryRule and DictionarySubstringRule:

WordListDictionary wordListDictionary = new WordListDictionary(
new ArrayWordList(new String[] { "bar", "foobar" }));


DictionaryRule dictionaryRule = new DictionaryRule(wordListDictionary);
DictionarySubstringRule dictionarySubstringRule = new DictionarySubstringRule(wordListDictionary);