@hackylabs/deep-redact

Deep Redact

Faster than Fast Redact ¹ as well as being safer and more configurable than many other redaction solutions, Deep Redact is a zero-dependency tool that redacts sensitive information from strings and objects. It is designed to be used in a production environment where sensitive information needs to be redacted from logs, error messages, files, and other outputs. Supporting both strings and objects or a mix of both, Deep Redact can be used to redact sensitive information from more data structures than any other redaction library. Even partially redacting sensitive information from strings is supported, by way of custom regex patterns and replacers.

Circular references and other unsupported values are handled gracefully, and the library is designed to be as fast as possible while still being easy to use and configure.

Supporting both CommonJS and ESM, with named and default exports, Deep Redact is designed to be versatile and easy to use in any modern JavaScript or TypeScript project in Node or the browser.

Installation

npm install @hackylabs/deep-redact

Usage

In order to maintain a consistent usage throughout your project, it is not advised to call this library outside of your global logging/error-reporting libraries.

// ./src/example.ts
import {DeepRedact} from '@hackylabs/deep-redact'; // If you're using CommonJS, import with require('@hackylabs/deep-redact') instead. Both CommonJS and ESM support named and default imports.

const objRedaction = new DeepRedact({
  blacklistedKeys: ['sensitive', 'password', /name/i],
})

const obj = {
  keepThis: 'This is fine',
  sensitive: 'This is not fine',
  user: {
    id: 1,
    password: '<h1><strong>Password</strong></h1>',
    firstName: 'John',
  }
}

// Recursively redact sensitive information from an object
objRedaction.redact(obj)
// {
//  keepThis: 'This is fine',
//  sensitive: '[REDACTED]',
//  user: {
//    id: 1,
//    password: '[REDACTED]',
//    firstName: '[REDACTED]'
//  }
// }

const strRedaction = new DeepRedact({
  partialStringTests: [
    {
      pattern: /<(email|password)>([^<]+)<\/\1>/gi,
      replacer: (value: string, pattern: RegExp) => value.replace(pattern, '<$1>[REDACTED]</$1>'),
    },
  ],
})

// Partially redact sensitive information from a string
strRedaction.redact('<email>[e-mail]</email><keepThis>This is fine</keepThis><password>secret</password>')
// '<email>[REDACTED]</email><keepThis>This is fine</keepThis><password>[REDACTED]</password>'

// Override the unsupportedTransformer method to handle unsupported values

class CustomRedaction extends DeepRedact {
  constructor(options) {
    super(options)
    this.rewriteUnsupported = (value) => {
      if (value instanceof BigInt) return value.toString()

      // Add more conditional statements for unsupported value types here (e.g. Error, Date, Map, Set, etc.)

      // If the value is supported, return it
      return value
    }
  }
}

const customRedaction = new CustomRedaction({
  blacklistedKeys: ['sensitive', 'password', /name/i],
})

customRedaction.redact({ a: BigInt(1) })

Configuration

Main Options

key	description	type	options	default	required
blacklistedKeys	Deeply compare names of these keys against the keys in your object.	array	Array<string￨RegExp￨BlacklistKeyConfig>	[]	N
stringTests	Array of regular expressions to perform against string values, whether that value is a flat string or nested within an object. Will redact whole string values. If you want to redact only part of the string, use partialStringTests instead. If a replacer function is provided in the config for the associated test, it will be used to redact the value.	array	Array<RegExp￨StringTestConfig>	[]	N
partialStringTests	Array of regular expressions to perform against string values, whether that value is a flat string or nested within an object. Will redact only the matched part of the string using the replacer function provided in the config for the associated test.	array	StringTestConfig[]	[]	N
fuzzyKeyMatch	Loosely compare key names by checking if the key name of your unredacted object is included anywhere within the name of your blacklisted key. For example, is "pass" (your key) included in "password" (from config).	boolean		false	N
caseSensitiveKeyMatch	Loosely compare key names by normalising the strings. This involves removing non-word characters and transforms the string to lowercase. This means you never have to worry having to list duplicate keys in different formats such as snake_case, camelCase, PascalCase or any other case.	boolean		true	N
remove	Determines whether or not to remove the key from the object when it is redacted.	boolean		false	N
retainStructure	Determines whether or not keep all nested values of a key that is going to be redacted. Circular references are always removed.	boolean		false	N
replacement	When a value is going to be redacted, what would you like to replace it with?	string ￨ function		[REDACTED]	N
replaceStringByLength	When a string value is going to be replaced, optionally replace it by repeating the replacement to match the length of the value. For example, if replaceStringByLength were set to true and replacement was set to "x", then redacting "secret" would return "xxxxxx". This is sometimes useful for debugging purposes, although it may be less secure as it could give hints to the original value.	boolean		false	N
types	JS types (values of typeof keyword). Only values with a typeof equal to string, number, bigint, boolean, symbol, object, or function will be redacted. Undefined values will never be redacted, although the type undefined is included in this list to keep TypeScript happy.	array	Array<'string'￨'number'￨'bigint'￨'boolean'￨'symbol'￨'undefined'￨'object'￨'function'>	['string']	N
serialise	Determines whether or not to serialise the object after redacting. Typical use cases for this are when you want to send it over the network or save to a file, both of which are common use cases for redacting sensitive information.	boolean		false	N
serialize	Alias of serialise for International-English users.	boolean		false	N

BlacklistKeyConfig

key	type	default	required
key	string￨RegExp		Y
fuzzyKeyMatch	boolean	Main options fuzzyKeyMatch	N
caseSensitiveKeyMatch	boolean	Main options caseSensitiveKeyMatch	N
remove	boolean	Main options remove	N
retainStructure	boolean	Main options retainStructure	N

StringTestConfig

key	description	type	required
pattern	A regular expression to perform against a string value, whether that value is a flat string or nested within an object.	RegExp	Y
replacer	A function that will be called with the value of the string that matched the pattern and the pattern itself. This function should return the new (redacted) value to replace the original value.	function	Y

Benchmark

Comparisons are made against JSON.stringify, Regex.replace, Fast Redact & (one of my other creations, @hackylabs/obglob) as well as different configurations of Deep Redact, using this test object. Fast Redact was configured to redact the same keys on the same object as Deep Redact without using wildcards.

The benchmark is run on a 2021 iMac with an M1 chip with 16GB memory running macOS Sequoia 15.0.0.

JSON.stringify is included as a benchmark because it is the fastest way to deeply iterate over an object, although it doesn't redact any sensitive information.

Regex.replace is included as a benchmark because it is the fastest way to redact sensitive information from a string. However, a regex pattern for all keys to be redacted is much harder to configure than a dedicated redaction library, especially when dealing with multiple types of values. It also doesn't handle circular references or other unsupported values as gracefully as deep-redact unless a third-party library is used to stringify the object beforehand.

Fast-redact is included as a benchmark because it's the next fastest library available specifically for redaction.

Neither JSON.stringify, Regex.replace nor Fast Redact offer the same level of configurability as deep-redact. Both Fast Redact and Obglob are slower and rely on dependencies.

scenario	ops / sec	op duration (ms)	margin of error	sample count
DeepRedact, partial redaction	176654.38	0.0056607711	0.00003	88329
JSON.stringify, large object	164287.01	0.0060869085	0.00002	82144
DeepRedact, remove item, single object	25142.69	0.0397729959	0.00029	12572
Regex replace, large object	23061.11	0.0433630529	0.00022	11531
DeepRedact, default config, large object	21454.71	0.0466098038	0.00086	10728
DeepRedact, custom replacer function, single object	21026.51	0.047559016	0.00047	10514
DeepRedact, replace string by length, single object	19629.37	0.0509440788	0.00032	9815
DeepRedact, retain structure, single object	18238.97	0.0548276723	0.00049	9120
DeepRedact, fuzzy matching, single object	17470.6	0.0572390237	0.00029	8736
DeepRedact, config per key, single object	15398.94	0.0649395488	0.00036	7700
DeepRedact, default config, 1000 large objects	8401.8	0.1190220507	0.00103	4201
fast redact, large object	5898.84	0.1695249305	0.00133	2950
ObGlob, large object	4876.54	0.2050635404	0.01142	2439
DeepRedact, case insensitive matching, single object	3576.62	0.279593299	0.00282	1789
DeepRedact, fuzzy and case insensitive matching, single object	3379.78	0.295877197	0.00244	1690
JSON.stringify, 1000 large objects	220.76	4.5298012342	0.10929	111
ObGlob, 1000 large objects	166.2	6.0168303571	0.07621	84
DeepRedact, partial redaction large string	126.88	7.8814680469	0.28048	64
fast redact, 1000 large objects	122.12	8.1884899032	0.06661	62
Regex replace, 1000 large objects	93.88	10.6515390208	0.36668	48