Philiprehberger.Masker

Mask and redact sensitive data in strings and objects for safe logging.

Installation

dotnet add package Philiprehberger.Masker

Usage

Built-In Patterns

using Philiprehberger.Masker;

var input = "Card: 4111-1111-1111-1234";
var masked = Masker.Mask(input, MaskPattern.CreditCard);
// "Card: ************1234"

Mask All Patterns at Once

var log = "User john@example.com called with SSN 123-45-6789";
var safe = Masker.MaskAll(log);
// "User j***@example.com called with SSN ***-**-6789"

Custom Regex Pattern

using System.Text.RegularExpressions;

var pattern = new Regex(@"API_KEY_\w+");
var result = Masker.Mask("Token: API_KEY_abc123xyz", pattern, revealStart: 0, revealEnd: 4);
// "Token: ***********xyz"

Object Masking

public class UserDto
{
    public string Name { get; set; } = "";

    [SensitiveData]
    public string Password { get; set; } = "";

    [SensitiveData(PatternName = "Email")]
    public string Email { get; set; } = "";
}

var user = new UserDto
{
    Name = "Alice",
    Password = "s3cret!pass",
    Email = "alice@example.com"
};

var safe = ObjectMasker.MaskObject(user);
// safe.Name     => "Alice"
// safe.Password => "*******pass"
// safe.Email    => "a****@example.com"

API

Masker

Method	Description
Mask(string input, MaskPattern pattern)	Mask using a built-in pattern
Mask(string input, Regex pattern, int revealStart, int revealEnd)	Mask using a custom regex with reveal options
MaskAll(string input)	Apply all built-in patterns to the input

MaskPattern

Property	Description
CreditCard	13-19 digit card numbers, reveals last 4
Email	Email addresses, masks local part
Phone	US phone numbers, reveals last 4 digits
SSN	Social Security Numbers, reveals last 4
JWT	JSON Web Tokens, fully redacted
BearerToken	Bearer auth tokens, fully redacted
ConnectionString	Password/secret values in connection strings

ObjectMasker

Method	Description
MaskObject<T>(T obj)	Create a masked clone of an object

SensitiveDataAttribute

Property	Description
PatternName	Optional pattern name to apply (e.g. "Email", "CreditCard")

MaskerOptions

Property	Default	Description
MaskChar	'*'	Character used for masking
RevealLength	4	Number of characters to leave visible
RevealEnd	true	Reveal at end (true) or start (false)

Development

dotnet build src/Philiprehberger.Masker.csproj --configuration Release

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License

MIT