anu1097/golang-masking-tool

A Simple to use golang masking tool to mask sensitive information from go-lang data-structures

Golang Masking Tool

Golang Masking Tool is a simple utility of creating a masker tool which you can use to mask sensitive information. You can use a variety of filters with custom masking types to assist you.

Inspired by two repositories -

1. zlog
2. Golang Masker

Both libraries were solving similar usecase but didn't cover all use cases I was looking for. Zlog is a libray that focuses more on logging and its filterating features are not exposed to be used separately. While Golang Masker doesn't cover all data types. Hence it didn't solve my use-cases.

So I combined both of them to create this library and sharing the best of both them. Added some more uses cases too.

• Getting Started

Getting Started

$ go get -u github.com/anu1097/golang-masking-tool

Usage

• Basic example
  • Creating a Masking Instance
• Filter sensitive data
  • By specified field
  • By specified field-prefix
  • By specified value
  • By custom type
  • By struct tag
  • By data pattern (e.g. personal information)
  • All Fields Filter
• Customise Masking Tool
  • Update Custom Masker Character
  • Update Default Filter
  • Append More Filters

Basic Example

Create Masking Instance

    var maskingInstance = NewMaskTool()

Filter Sensitive Data

By Specified Field

Default

	type myRecord struct {
		ID    string
		Phone string
	}
	record := myRecord{
		ID:    "userId",
		Phone: "090-0000-0000",
	}

	maskTool := NewMaskTool(filter.FieldFilter("Phone"))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId [filtered]}

Custom Mask Type

	type myRecord struct {
		ID         string
		Phone      string
		Url        string
		Email      string
		Name       string
		Address    string
		CreditCard string
	}
	record := myRecord{
		ID:         "userId",
		Phone:      "090-0000-0000",
		Url:        "http://admin:mysecretpassword@localhost:1234/uri",
		Email:      "[email protected]",
		Name:       "John Doe",
		Address:    "1 AB Road, Paradise",
		CreditCard: "4444-4444-4444-4444",
	}

	maskTool := NewMaskTool(
		filter.CustomFieldFilter("Phone", customMasker.MMobile),
		filter.CustomFieldFilter("Email", customMasker.MEmail),
		filter.CustomFieldFilter("Url", customMasker.MURL),
		filter.CustomFieldFilter("Name", customMasker.MName),
		filter.CustomFieldFilter("ID", customMasker.MID),
		filter.CustomFieldFilter("Address", customMasker.MAddress),
		filter.CustomFieldFilter("CreditCard", customMasker.MCreditCard),
	)
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId**** 090-***0-0000 http://admin:xxxxx@localhost:1234/uri dum****@dummy.com J**n D**e 1 AB R****** 4444-4******44-4444}

By Specified Field-Prefix

Default

	type myRecord struct {
		ID          string
		SecurePhone string
	}
	record := myRecord{
		ID:          "userId",
		SecurePhone: "090-0000-0000",
	}

	maskTool := NewMaskTool(filter.FieldPrefixFilter("Secure"))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId [filtered]}

Custom

	maskTool := NewMaskTool(filter.CustomFieldPrefixFilter("Secure", customMasker.MMobile))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId 090-***0-0000}

By Specified Value

Default

	const issuedToken = "abcd1234"
	maskTool := NewMaskTool(filter.ValueFilter(issuedToken))
	record := "Authorization: Bearer " + issuedToken
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// Authorization: Bearer [filtered]

Custom Mask Type

	const issuedToken = "abcd1234"
	maskTool := NewMaskTool(filter.CustomValueFilter(issuedToken, customMasker.MPassword))
	record := "Authorization: Bearer " + issuedToken
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// Authorization: Bearer ************

By custom type

Default

	type password string
	type myRecord struct {
		ID       string
		Password password
	}
	record := myRecord{
		ID:       "userId",
		Password: "abcd1234",
	}
	maskTool := NewMaskTool(filter.CustomTypeFilter(password(""), customMasker.MPassword))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId [filtered]}

Custom Mask Type

	type password string
	type myRecord struct {
		ID       string
		Password password
	}
	record := myRecord{
		ID:       "userId",
		Password: "abcd1234",
	}

	maskTool := NewMaskTool(filter.CustomTypeFilter(password(""), customMasker.MPassword))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId ************}

By struct tag

Default

	type myRecord struct {
		ID    string
		EMail string `mask:"secret"` //Use secret for default filter
	}
	record := myRecord{
		ID:    "userId",
		EMail: "[email protected]",
	}

	maskTool := NewMaskTool(filter.TagFilter())
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId [filtered]}

Custom Mask Type

	type myRecord struct {
		ID    string
		EMail string `mask:"email"`
		Phone string `mask:"mobile"`
	}
	record := myRecord{
		ID:    "userId",
		EMail: "[email protected]",
		Phone: "9191919191",
	}

	maskTool := NewMaskTool(filter.TagFilter(customMasker.MEmail, customMasker.MMobile))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId dum****@dummy.com 9191***191}

By Regex Pattern

Default Phone Filter

	type myRecord struct {
		ID    string
		Phone string
	}
	record := myRecord{
		ID:    "userId",
		Phone: "090-0000-0000",
	}
	maskTool := NewMaskTool(filter.PhoneFilter())
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId [filtered]}

Custom Phone Filter

	type myRecord struct {
		ID    string
		Phone string
	}
	record := myRecord{
		ID:    "userId",
		Phone: "090-0000-0000",
	}
	maskTool := NewMaskTool((filter.CustomPhoneFilter(customMasker.MMobile)))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	//{userId 090-***0-0000}

Default Email Filter

	type myRecord struct {
		ID    string
		Email string
	}
	record := myRecord{
		ID:    "userId",
		Email: "[email protected]",
	}
	maskTool := NewMaskTool(filter.EmailFilter())
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId [filtered]}

Custom Email Filter

	type myRecord struct {
		ID    string
		Email string
	}
	record := myRecord{
		ID:    "userId",
		Email: "[email protected]",
	}
	maskTool := NewMaskTool(filter.EmailFilter())
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId dum****@dummy.com}

Custom Regex Filter

	customRegex := "^https:\\/\\/(dummy-backend.)[0-9a-z]*.com\\b([-a-zA-Z0-9@:%_\\+.~#?&//=]*)$"
	type myRecord struct {
		ID   string
		Link string
	}
	record := myRecord{
		ID:   "userId",
		Link: "https://dummy-backend.dummy.com/v2/random",
	}
	maskTool := NewMaskTool(filter.CustomRegexFilter(customRegex))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId [filtered]}

Custom Regex Filter With Mask Type

	type myRecord struct {
		ID   string
		Link string
	}
	record := myRecord{
		ID:   "userId",
		Link: "https://dummy-backend.dummy.com/v2/random",
	}
	maskTool := NewMaskTool(filter.CustomRegexFilterWithMType(customRegex, customMasker.MPassword))
	filteredData := maskTool.MaskDetails(record)

	// fmt.Println(filteredData)
	// {userId ************}

By AllFields Filter

Default

	type child struct {
		Data string
	}
	s := "test"
	type myStruct struct {
		Func      func() time.Time
		Chan      chan int
		Bool      bool
		Bytes     []byte
		Strs      []string
		StrsPtr   []*string
		Interface interface{}
		Child     child
		ChildPtr  *child
		Data      string
	}
	data := &myStruct{
		Func:      time.Now,
		Chan:      make(chan int),
		Bool:      true,
		Bytes:     []byte("timeless"),
		Strs:      []string{"aa"},
		StrsPtr:   []*string{&s},
		Interface: &s,
		Child:     child{Data: "x"},
		ChildPtr:  &child{Data: "y"},
		Data:      "data",
	}
	mask := NewMaskingInstance(
		filter.AllFieldFilter(),
	)

	filteredData := mask.MaskDetails(data)

	// fmt.Println(filteredData)
	// {<nil> <nil> false [] [] [] <nil> {} 0x1400009b180 [filtered]}

With Custom Mask Type

	mask := NewMaskingInstance(
		filter.CustomAllFieldFilter(customMasker.MPassword),
	)
	filteredData := mask.MaskDetails(data)

	// fmt.Println(filteredData)
	// {<nil> <nil> false [] [] [] <nil> {} 0x1400009b180 ************}

Custom Mask Types

Type	Const	Tag	Description
Name	MName	name	mask the second letter and the third letter
Password	MPassword	password	always return ************
Address	MAddress	addr	keep first 6 letters, mask the rest
Email	MEmail	email	keep domain and the first 3 letters
Mobile	MMobile	mobile	mask 3 digits from the 4'th digit
Telephone	MTelephone	tel	remove (, ), , - chart, and mask last 4 digits of telephone number, format to (??)????-????
ID	MID	id	mask last 4 digits of ID number
CreditCard	MCreditCard	credit	mask 6 digits from the 7'th digit
Secret	MStruct	secret	Uses default filtered string. Use only with Struct Tag filter

Customise Masking Tool

Update Default Filter

	maskTool := NewMaskTool(filter.FieldFilter("Phone"))
	maskTool.SetFilteredLabel("CustomFilterString")
	// maskTool.GetFilteredLabel()
    // CustomFilterString

Update Custom Masker Character

	maskTool := NewMaskTool(filter.FieldFilter("Phone"))
	maskTool.UpdateCustomMaskingChar(customMasker.PCross)

Append More Filter

	maskTool := NewMaskTool(filter.FieldFilter("Phone"))
	maskTool.AppendFilters(filter.EmailFilter())

License

• MIT License
• Author: Anuraag Gupta [email protected]

golang-masking-tool's Issues

Not able to mask struct

I wasn't able to mask generated struct by protobuf. Is it possible to mask nested struct types?

Nil value passed to maskdetails panics

Describe the bug
The code handles nil ptrs and other complex stuff well but there is one bug that happens if the value of the instance passed to maskDetails is nil. Of course it is silly to pass nil but sometimes the caller might now know (I hit this on an interceptor on a use case where one object was nil)

The original masker code that this was inspired from does handle that case right away

https://github.com/ggwhite/go-masker/blob/master/masker.go#L111-L113

To Reproduce
Very simple, just

1. Create a new masking instance
2. call masker.MaskDetails(nil)

Expected behavior
This seems like a gray are because it is an error to pass a nil, so either change MaskDetails to pass an error or, if nil is passed, just return nil?

Syntax highlight in readme.md

Describe the bug
Is not a bug, is a improvement for documentation reading.

Screenshots

Readme.md