@digitalcredentials/bnid

JavaScript Base-N Id Generator (@digitalcredentials/bnid)

A JavaScript library for Web browsers, React Native, and Node.js apps to generate random ids and encode and decode them using various base-N encodings.

Table of Contents

• Background
• Install
• Usage
• API
• CLI
• Contribute
• Commercial Support
• License

Background

This library provides tools for Web and Node.js to generate random ids and encode and decode them in various base-N encodings.

Install

NPM

npm install bnid

Git

To install locally (for development):

git clone https://github.com/digitalcredentials/bnid.git
cd bnid
npm install

Usage

The interface follows the TextEncoder/TextDecoder interfaces and provides IdEncoder and IdDecoder classes. Instances can be configured with reusable encodings and other parameters. The encoder operates on a Uint8Array of input bytes. A IdGenerator class is provided that can be used to generate random ids with selectable bit lengths, but any id data can be used.

The encoder and decoder support various encodings and options:

• base16/hex, base16upper: The simple Base16.
• base58/base58btc: The Base58 Bitcoin alphabet as supported by base58-universal.
• Optional multibase type prefix.
• Fixed bit length. This is useful to ensure the output id length is constant even when the id starts with an arbitrary number of zeros.

The fixed length options can be important when using encodings that have variable length outputs depending on the input length. base58btc is and example. When encoding, the fixedLength or fixedBitLength options can be used to force the output to be a constant length. When decoding, the fixedBitLength options can be used to ensure a constant length array of bytes.

Generate an ID

To generate a default Base58, 128 bit, non-fixed-length, multibase encoded id:

import {generateId} from '@digitalcredentials/bnid';

const id = await generateId();

To generate a Base58, 128 bit, fixed-length id:

import {generateId} from '@digitalcredentials/bnid';

const id = await generateId({
  fixedLength: true
});

Reusable Components

Some setup overhead can be avoided by using the component IdGenerator and IdEncoder classes.

import {IdGenerator, IdEncoder} from 'bnid';

// 64 bit random id generator
const generator = new IdGenerator({
  bitLength: 64
});
// base58, multibase, fixed-length encoder
const encoder = new IdEncoder({
  encoding: 'base58',
  fixedLength: true,
  multibase: true
});
const id1 = encoder.encode(await generator.generate());
const id2 = encoder.encode(await generator.generate());

Reusable Components

Some setup overhead can be avoided by using the component IdGenerator and IdEncoder classes.

import {IdGenerator, IdEncoder, IdDecoder} from '@digitalcredentials/bnid';

// 64 bit random id generator
const generator = new IdGenerator({
  bitLength: 64
});
// base58, multibase, fixed-length encoder
const encoder = new IdEncoder({
  encoding: 'base58',
  fixedLength: true,
  multibase: true
});
const id1 = encoder.encode(await generator.generate());
// => "z..."
const id2 = encoder.encode(await generator.generate());
// => "z..."

const decoder = new IdDecoder({
  fixedBitLength: 64,
  multibase: true
});
const id1bytes = decoder.decode(id1);
// => Uint8Array([...])
const id2bytes = decoder.decode(id2);
// => Uint8Array([...])

API

generateId(options)

Generate a string id. See IdGenerator and IdEncoder for options.

decodeId(options)

Decode the options.id string. See IdDecoder for other options.

IdGenerator

An IdGenerator generates an array of id bytes.

constuctor(options) / constructor(bitLength)

Options:

• bitLength: Number of id bits. Must be multiple of 8. (default: 128)

generate()

Generate random id bytes.

IdEncoder

An IdEncoder encodes an array of id bytes into a specific encoding.

constuctor(options)

Options:

• encoding: Output encoding. (default: base58)
  • base16/base16upper/hex: base16 encoded string.
  • base58/base58btc: base58btc encoded string.
• fixedLength: true to ensure fixed output length. (default: false)
• fixedBitLength: fixed output bit length or 0 to base on input byte size. (default: 0)
• multibase: true to use multibase encoding. (default: true)
• multihash: true to use multihash encoding. (default: false)

encode(bytes)

Encode id bytes into a string.

IdDecoder

An IdDecoder decodes a specific encoding into an array of bytes representing an ID.

constuctor(options)

Options:

• encoding: Input encoding. Ignored if multibase is true. (default: base58)
  • Same options as for IdEncoder.
• fixedBitLength: fixed output bit length. (default: none)
• multibase: true to use multibase encoding to detect id format. (default: true)
• multihash: true to use multihash encoding. (default: false)
• expectedSize: Expected size for multihash-encoded ID bytes. Use 0 to disable size check. (default: 32)

decode(id)

Decode id string into bytes.

minEncodedIdBytes(options)

Minimum number of bytes needed to encode an id of a given bit length.

Options:

• encoding: Encoding. (default: base58)
• bitLength: Number of id bits. (default: 128)
• multibase: Account for multibase encoding. (default: true)

maxEncodedIdBytes(options)

Maximum number of bytes needed to encode an id of a given bit length.

Options:

• encoding: Encoding. (default: base58)
• bitLength: Number of id bits. (default: 128)
• multibase: Account for multibase encoding. (default: true)

generateSecretKeySeed(options)

generateSecretKeySeed() and decodeSecretKeySeed() methods are for creating and decoding secret key pair seeds which can be used to generate public key based identifiers.

generateSecretKeySeed() generates a secret key seed encoded as a string that can be stored and later used to generate a key pair. The public key from the key pair can be used as an identifier. The encoded key seed MUST be kept secret.

import {generateSecretKeySeed} from '@digitalcredentials/bnid';

const secretKeySeed = await generateSecretKeySeed();
// Example secretKeySeed: z1Aaj5A4UCsdMpXwdYAReXa4bxWYiKJtdAvB1zMzCHtCbtD

Options:

• encoding: Encoding. (default: base58)
• bitLength: Number of id bits. (default: 32 * 8)
• multibase: Account for multibase encoding. (default: true)
• multihash: Account for multihash encoding. (default: true)

decodeSecretKeySeed(options)

Decodes an encoded secret key seed into an array of secret key seed bytes (default size: 32 bytes). Both the encoded key seed and the decoded bytes MUST be kept secret.

import {decodeSecretKeySeed} from '@digitalcredentials/bnid';

const secretKeySeed = 'z1Aaj5A4UCsdMpXwdYAReXa4bxWYiKJtdAvB1zMzCHtCbtD';
decoded = decodeSecretKeySeed({secretKeySeed});
// Example decoded:
// Uint8Array(32) [
//    80, 174,  15, 131, 124,  59,   9,  51,
//   145, 129,  92, 157, 157, 172, 161,  79,
//    74,  61, 152, 152,  48, 151,  20,  89,
//   225, 169,  71,  34,  49,  61,  21, 215
// ]

Options:

• secretKeySeed: The secret key seed to be decoded.
• multibase: Account for multibase encoding. (default: true)
• multihash: Account for multihash encoding. (default: true)
• expectedSize: Expected size for multihash-encoded ID bytes. Use 0 to disable size check. (default: 32)

CLI

A command line interface tool to generate and encode ids is provided in bnid-cli.

Contribute

Please follow the existing code style.

PRs accepted.

If editing the README, please conform to the standard-readme specification.

License

• MIT License - DCC - TypeScript and ReactNative compatibility.
• BSD-3-Clause © Digital Bazaar