Password Tester

This TypeScript library provides a function to test the strength of passwords based on their entropy and whether the password has been reused according to the Have I Been Pwned database. It exports types for password error codes, strength levels, and a report interface.

Installation

You can install the library via npm:

npm install --save-exact password-tester

Important

We use --save-exact in the install command because this library is intended to test highly confidential passwords. Adding this flag pins the package to the current version of the library. It is a best practice to fix the package version on code that you have personally read and understand.

Usage

Simple Usage

import { testPassword } from 'password-tester';

// Test password strength
const report = await testPassword("MySuperSecurePassword123!");

// Output result
console.log(report);
/* Will output:
  {
    strength: 'EXCELLENT',
    strengthLevel: 5,
    entropy: 104.24812503605781
  }
*/

With Options

import { testPassword, PasswordReport, TestPasswordOptions } from 'password-tester';

// Define password
const password: string = "MySuperSecurePassword123!";

/*
  Optional configuration for testing password
  (if this parameter is omitted, or a field left empty, the options will be set
  to the safest possible by default)
*/
const options: TestPasswordOptions = {
  enableEntropyLowerBound: true,
  enableReUsedPasswordCheck: true,
  requireReUsedPasswordCheckSuccess: true
};

// Test password strength
const report: PasswordReport = await testPassword(password, options);

// Output result
console.log(report);
/* Will output:
  {
    strength: 'EXCELLENT',
    strengthLevel: 5,
    entropy: 104.24812503605781
  }
*/

API

testPassword(password: string, options?: TestPasswordOptions): PasswordReport

This function tests the strength of a given password and returns a report object.

• password: The password string to test.
• options: Optional configuration object. Currently supports disabling the entropy lower bound check.

Types

TestPasswordOptions

type TestPasswordOptions = {
  enableEntropyLowerBound?: boolean;
  enableReUsedPasswordCheck?: boolean
  requireReUsedPasswordCheckSuccess?: boolean
};

• enableEntropyLowerBound: Ensures that a report will include an error if the entropy is too low. If this field is omitted, this will be true by default.
• enableReUsedPasswordCheck: Will check the password to see if it has been previously exposed in a breach using the Have I Been Pwned database. If this field is omitted, this will be true by default.
• requireReUsedPasswordCheckSuccess: Will return an errorCode in the report if the Have I Been Pwned database check fails. If false, then instead of an errorCode, a warningCode will be returned and the rest of the report will read as if the database check was successful.

PasswordReport

type PasswordReport = {
  strength: PasswordStrength;
  strengthLevel: PasswordStrengthLevel;
  entropy: number;
  warningCode?: PasswordWarningCode;
  errorCode?: PasswordErrorCode;
};

• strength: Password strength represented as PasswordStrength type.
• strengthLevel: Password strength level represented as PasswordStrengthLevel type.
• entropy: Entropy value calculated for the password.
• warningCode: Optional warning code to alert you if the password test encounters a non-blocking issue.
• errorCode: Optional error code if the password test encounters an error.

PasswordWarningCode

export type PasswordWarningCode = "PASSWORD_PREVIOUSLY_EXPOSED" | "FAILED_TO_CHECK_PASSWORD_REUSE";

• PASSWORD_PREVIOUSLY_EXPOSED: It has been detected that the password tested has already been hacked and exposed as part of a password breach, according to Have I Been Pwned. The password strength, should always be POOR.
• FAILED_TO_CHECK_PASSWORD_REUSE: If the option to requireReUsedPasswordCheckSuccess is false, then this warning may show. It means that it was not possible to check the password breach database, and it cannot be verified if the password has already been exposed.

PasswordErrorCode

type PasswordErrorCode = "MIN_CHARS_NOT_MET" | "ENTROPY_TOO_LOW" | "FAILED_TO_CHECK_PASSWORD_REUSE";

• MIN_CHARS_NOT_MET: Error code indicating the password does not meet the minimum character requirement (8 characters).
• ENTROPY_TOO_LOW: Error code indicating the password's entropy is too low (less than 25 bits of entropy).
• FAILED_TO_CHECK_PASSWORD_REUSE: The library was unable to get a response from Have I Been Pwned to check if the password has been previously exposed.

PasswordStrength

type PasswordStrength = "EXCELLENT" | "VERY_GOOD" | "GOOD" | "FAIR" | "POOR" | "ERROR";

• EXCELLENT: Represents excellent password strength (100 or more bits of entropy).
• VERY_GOOD: Represents very good password strength (80 or more bits of entropy).
• GOOD: Represents good password strength (80 or more bits of entropy).
• FAIR: Represents fair password strength (60 or more bits of entropy).
• POOR: Represents poor password strength (over 25 bits of entropy, or a reused password).
• ERROR: Represents an error state.

PasswordStrengthLevel

type PasswordStrengthLevel = 5 | 4 | 3 | 2 | 1 | 0;

• 5: Excellent password strength level.
• 4: Very good password strength level.
• 3: Good password strength level.
• 2: Fair password strength level.
• 1: Poor password strength level.
• 0: Error, no password strength level.

License

This library is released under the MIT or Apache-2 License.