Package dev.blaauwendraad.masker.json

Class ValueMaskers

java.lang.Object
dev.blaauwendraad.masker.json.ValueMaskers
public final class ValueMaskers extends Object
Provides out-of-the-box implementations of ValueMasker.

  • Method Details

    • describe

      public static <T extends ValueMasker> T describe(String description, T delegate)
      Provides information about the ValueMasker implementation. Which is useful for debugging and testing purposes.
      See Also:
      • DescriptiveValueMasker

    • with

      public static ValueMasker.AnyValueMasker with(String value)
      Masks a target value with a static string value.

      For example, "maskMe": "secret" -> "maskMe": "***".

    • with

      public static ValueMasker.AnyValueMasker with(int value)
      Masks a target value with a static integer value.

      For example, "maskMe": 12345 -> "maskMe": 0.

    • with

      public static ValueMasker.AnyValueMasker with(boolean value)
      Masks a target value with a static boolean value.

      For example, "maskMe": true -> "maskMe": false.

    • withNull

      public static ValueMasker.AnyValueMasker withNull()
      Masks a target value with null.

    • eachCharacterWith

      public static ValueMasker.StringMasker eachCharacterWith(String value)
      Masks all characters of a target string value with a static string value.

      For example, "maskMe": "secret" -> "maskMe": "******".

      Note: this implementation only replaces visible characters with a mask, meaning that JSON escape character ('\') will not count towards the length of the masked value and the unicode characters ('\u1000'), including 4-byte UTF-8 characters ('\uD83D \uDCA9'), will only count as a single character in the masked value.

    • eachDigitWith

      public static ValueMasker.NumberMasker eachDigitWith(int digit)
      Masks all digits of a target numeric value with a static digit.

      For example, "maskMe": 12345 -> "maskMe": 88888.

    • noop

      public static ValueMasker.AnyValueMasker noop()
      Does not mask a target value (no-operation). Can be used if certain JSON value types do not need to be masked, for example, not masking booleans or numbers.
      See Also:

    • email

      public static ValueMasker.StringMasker email(int keepPrefixLength, int keepSuffixLength, boolean keepDomain, String mask)
      Masks a target string value (containing an email) while keeping some number of the prefix or suffix characters and the ability to keep the domain unmasked.

      For example:

      Parameters:
      keepPrefixLength - amount of prefix characters to keep unmasked
      keepDomain - if true - the email domain will remain unmasked
      mask - the static mask applied to the rest of the value

    • withRawValueFunction

      public static ValueMasker.AnyValueMasker withRawValueFunction(Function<String,String> masker)
      Masks a target value with the provided Function. The target value (as raw JSON literal) is passed into the function as a string regardless of the JSON type (string, numeric or a boolean). In case the target value is a JSON string the value the function will receive a JSON encoded value with the quotes as it appears in the JSON with line breaks encoded as \n, special characters like " or \ escaped with a backslash (\).

      Consequently, the return value of the provided function must be a valid JSON encoded literal (of any JSON type), otherwise the masking will result in an invalid JSON.

      The table below contains a couple examples for the masking

      Examples of using withRawValueFunction
      Input JSON Function Masked JSON
      { "maskMe": "a secret" } value -> value.replaceAll("secret", "***") { "maskMe": "a ***" }
      { "maskMe": 12345 } value -> value.startsWith(123) ? "0" : value { "maskMe": 0 }
      { "maskMe": "secret" } value -> "***" { "maskMe": *** } (invalid JSON)
      { "maskMe": "secret" } value -> "\"***\"" { "maskMe": "***" } (valid JSON)
      { "maskMe": "secret value" } value -> value.substring(0, 3) + "***" { "maskMe": "se*** } (invalid JSON
      { "maskMe": "secret value" } value -> value.startsWith("\"") ? value.substring(0, 4) + "***\"" : value { "maskMe": "sec***" } (valid JSON)
      { "maskMe": "Andrii \"Juice\" Pilshchykov" } value -> value.replaceAll("\"", "(quote)") { "maskMe": "Andrii \(quote)Juice\(quote) Pilshchykov" } (invalid JSON)
      { "maskMe": "Andrii \"Juice\" Pilshchykov" } value -> value.replaceAll("\\\"", "(quote)") { "maskMe": "Andrii (quote)Juice(quote) Pilshchykov" } (valid JSON)

      Note: usually the ValueMasker operates on a byte level without parsing JSON values into intermediate objects. This implementation, however, needs to allocate a String before passing it into the function and then turn it back into a byte array for the replacement, which introduces some performance overhead.