public-id

This project provides a small utility for numerical ID obscuration for public display or referencing. It converts a number like 19 to a string like ivUVjy0Q, and a given string ("public ID") can be converted back to the original number.

One special feature of this function is, that a number can be converted to several, various string values depending on random values, but each possible string can be mapped to exactly one number.

Example

const publicId = require('public-id');
 
publicId(19).then(generatedId => {
  console.log('public id:', generatedId);
  
  publicId('ivUVjy0Q').then(id => {
    console.log('id:', id);
  });
});

Using a generator instance:

const {PublicIdGenerator} = require('public-id');
 
const generator = new PublicIdGenerator();
 
generator.generate(19).then(generatedId => {
  console.log('public id:', generatedId);
  
  generator.decode('ivUVjy0Q').then(id => {
    console.log('id:', id);
  });
});

Platform Support

Platform	Support
Node.js	7.10.1+, 8.x and up
Chrome	55+
Edge	Yes
Firefox	52+
IE	No
Opera	42+
Safari	10.1+

Installation and Usage

Node.js

Use npm to install the package:

$ npm install --save public-id

Now require that package in your code:

const publicId = require('public-id');
const {PublicIdGenerator} = require('public-id');
 
async main() {
  console.log(await publicId(12));
  
  const generator = new PublicIdGenerator();
  console.log(await generator.generate(12));
}
 
main();

Browser

Just download the index.js, rename it to public-id.js or whatever you like and include it in your HTML file:

<script src="public-id.js"></script>
<script>
async main() {
  console.log(await publicId(12));
  
  const {PublicIdGenerator} = publicId;
  const generator = new PublicIdGenerator();
  console.log(await generator.generate(12));
}
</script> 

AMD

If you're using AMD, publicId is not exported globally. You can access it like this:

define(['public-id'], async (publicId) => {
  console.log(await publicId(12));
  
  const {PublicIdGenerator} = publicId;
  const generator = new PublicIdGenerator();
  console.log(await generator.generate(12));
});

API

publicId(id: number, length?: number, random?: number[] | Function)

• id: the numerical ID to be encoded; must be >= 1
• length: desired length of output string
• random: either an array of numbers between 0 (inclusive) and 1 (exclusive), or a function that returns a Promise that is resolved to such a number
• returns: Promise<string>

Generate an obscured public id from a number.

publicId(publicId: string)

• returns: Promise<number>

Convert a public ID back to number.

publicId.configure(options: Object)

Change the configuration. Only changes options, that are specified in the parameter object.

publicId.configure({
  key: 'awesome',
  index: 'abcdefghijklmnopqrstuvwxyz',
  defaultIdLength: 10
});

See Options below for more details.

publicId.resetConfiguration()

Reset options to the initial values.

PublicIdGenerator.constructor(options?: Object)

Constructor for a new PublicIdGenerator. See Options below for possible options.

const generator = new PublicIdGenerator(options);

PublicIdGenerator#publicId(id: number, length?: number, random?: number[] | Function)

• id: the numerical ID to be encoded; must be >= 1
• length: desired length of output string
• random: either an array of numbers between 0 (inclusive) and 1 (exclusive), or a function that returns a Promise that is resolved to such a number
• returns: Promise<string>

Generate an obscured public id from a number.

• alias: generate(), encode()

PublicIdGenerator#publicId(publicId: string)

• returns: Promise<number>

Convert a public ID back to number.

• alias: decode()

PublicIdGenerator#configure(options: Object)

Change some configurations.

generator.configure({
  key: 'awesome',
  index: 'abcdefghijklmnopqrstuvwxyz',
  defaultIdLength: 10
});

See Options below for more details.

PublicIdGenerator#resetConfiguration()

Reset options to the initial values.

Options

• key: (string) the key, that is used to encode and decode the IDs. If you change your key, all your generated public IDs become invalid.
• index: (string) possible characters, that are used in the public IDs. If you change your index or change the order of the characters, all your generated public IDs become invalid.
• defaultIdLength: (number, default 8) the output length of generated public IDs, if no other length is specified by parameter.
• signatureLength: (number, default 2) number of characters within the generated public ID, which indicates the random value of the output. If set to 0, every numerical ID corresponds to exactly one possible public ID. If you change this value, all your generated public IDs become invalid.
• randomFunction: (function) a custom random number generator. Must return a Promise, which resolves to a number between 0 (inclusive) and 1 (exclusive).

Custom Random Function

By default, Math.random() is used to generate random values. If you need more security, you can use a more secure random function like crypto.getRandomValues() in the browser or the crypto module in Node.js.

// in the browser
publicId.configure({
  async randomFunction() {
    const array = new Uint32Array(1);
    window.crypto.getRandomValues(array);
    
    return array[0] / (256 ** 4);
  }
});

// in Node.js
const crypto = require('crypto');
 
publicId.configure({
  randomFunction() {
    return new Promise((resolve, reject) => {
      crypto.randomBytes(1, (error, buffer) => {
        if(error) {
          return reject(error);
        }
        
        resolve(buffer[0] / 256);
      });
    });
  }
});

Max ID

Depending on the raw output length (i.e. the total length minus the signature length) and the number of characters available there's a limit for the maximum numerical ID that can be encoded. The following tables shows some sample configurations and the maximum IDs:

Signature	Length	Raw Length	Index	Min ID	Max ID	Fits in
2	8	6	62 (A-Z, a-z, 0-9)	1	56800235584	5 bytes
2	8	6	26 (a-z)	1	308915776	4 bytes
1	8	7	62 (A-Z, a-z, 0-9)	1	3521614606208	6 bytes
4	12	8	62 (A-Z, a-z, 0-9)	1	218340105584896	6 bytes
2	12	10	62 (A-Z, a-z, 0-9)	1	839299365868340200	8 bytes

You can use the maxId() method to get the maximum ID possible using the current configuration.

License

public-id is licensed under the MIT License.