maskjson

maskjson is a Go library for masking sensitive data in JSON. It allows you to easily hide sensitive information when marshaling structs to JSON by using struct tags.

Installation

go get github.com/henry.chu/maskjson

Usage

Basic Usage

package main

import (
    "fmt"
    "github.com/henry.chu/maskjson"
)

type User struct {
    Username string `json:"username"`
    Password string `json:"password" mask:"true"` // This field will be masked
    Email    string `json:"email" mask:"true"`    // This field will be masked
}

func main() {
    user := User{
        Username: "johndoe",
        Password: "secret123",
        Email:    "john.doe@example.com",
    }
    
    // Create a new masker with default settings
    // Parameters: fullMask (bool), atLeastStar (uint)
    // - fullMask: if true, completely masks the value
    // - atLeastStar: minimum number of asterisks to use for masking
    masker := maskjson.NewMask(false, 3)
    
    // Marshal the struct with masked fields
    jsonData, err := masker.Marshal(user)
    if err != nil {
        panic(err)
    }
    
    fmt.Println(string(jsonData))
    // Output: {"username":"johndoe","password":"sec*****","email":"john**************"}
}

Masking Options

The NewMask function accepts two parameters:

1. fullMask bool: When set to true, the entire value will be masked regardless of its length. When false, a portion of the beginning of the value will be visible.
2. atLeastStar uint: The minimum number of asterisks to use for masking. This ensures that sensitive fields are masked with at least this many asterisks.

How Masking Works

When fullMask is set to false:

• For strings, a small portion at the beginning is kept visible, and the rest is masked with asterisks
• The number of visible characters depends on the string length and the atLeastStar value
• Non-string values are completely masked with asterisks

When fullMask is set to true:

• All values are completely masked with asterisks, regardless of their type or length

License

MIT License