JavaScript Base-N Id Generator _(bnid)_


> A JavaScript library for Web browsers 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

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``
npm install bnid
`

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To install locally (for development):

`
git clone https://github.com/digitalbazaar/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.

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

`js
import {generateId} from 'bnid';

const id = await generateId();
`

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

`js
import {generateId} from 'bnid';

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

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

`js
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());
`

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

`js
import {IdGenerator, IdEncoder, IdDecoder} 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());
// => "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

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

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

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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.

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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.

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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.

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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)

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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)

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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.

`js
import {generateSecretKeySeed} from '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)

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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.

`js
import {decodeSecretKeySeed} from '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.

Commercial Support

Commercial support for this library is available upon request from
Digital Bazaar: support@digitalbazaar.com

License

BSD-3-Clause © Digital Bazaar

[Base16]: https://en.wikipedia.org/wiki/Base16
[Base58]: https://en.wikipedia.org/wiki/Base58
[TextDecoder]: https://developer.mozilla.org/en-US/docs/Web/API/TextEncoder
[TextEncoder]: https://developer.mozilla.org/en-US/docs/Web/API/TextDecoder
[base58-universal]: https://github.com/digitalbazaar/base58-universal
[multibase]: https://github.com/multiformats/multibase