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Cryptographic Key Pair Library for Linked Data (crypto-ld)
A Javascript library for generating and performing common operations on Linked Data cryptographic key pairs.
Table of Contents
Background
See also (related specs):
Supported Key Types (crypto-ld versions 4+)
This library provides general Linked Data cryptographic key generation functionality, but does not support any individual key type by default.
To use it, you must install individual driver libraries for each cryptographic key type. The following libraries are currently supported.
| Type | Crypto Suite | Library | Usage |
|---|---|---|---|
Ed25519 |
Ed25519VerificationKey2020 (recommended), Ed25519VerificationKey2018 (legacy) | ed25519-verification-key-2020 >=1.0 (recommended), ed25519-verification-key-2018 >=2.0 (legacy) |
Signatures, VCs, zCaps, DIDAuth |
X25519/Curve25519 |
X25519KeyAgreementKey2019 | x25519-key-agreement-key-2019 >=4.0 |
ECDH key agreement, JWE/CWE encryption with minimal-cipher |
Secp256k1 |
EcdsaSecp256k1VerificationKey2019 | ecdsa-secp256k1-verification-key-2019 |
Signatures, VCs, zCaps, DIDAuth, HD Wallets |
Legacy Supported Key Types (crypto-ld versions <=3)
In the previous version (v3.x) of crypto-ld, the RSA and Ed25519 suites were
bundled with crypto-ld (as opposed to residing in standalone packages).
For previous usage instructions of bundled RSA, Ed25519 and standalone
Curve25519/x25519-key-pair
type keys, see the README for crypto-ld v3.9.
Choosing a Key Type
For digital signatures using the
jsonld-signatures,
signing of Verifiable Credentials using vc-js,
authorization capabilities, and DIDAuth operations:
- Prefer Ed25519VerificationKey2020 type keys, by default.
- Use EcdsaSepc256k1 keys if your use case requires it (for example, if you're developing for a Bitcoin-based or Ethereum-based ledger), or if you require Hierarchical Deterministic (HD) wallet functionality.
For key agreement protocols for encryption operations:
- Use Curve25519 with the
minimal-cipherlibrary.
Security
As with most security- and cryptography-related tools, the overall security of your system will largely depend on your design decisions.
Install
- Node.js 14.0+ is required.
To install locally (for development):
git clone https://github.com/digitalbazaar/crypto-ld.git
cd crypto-ld
npm installUsage
Installing Support for Key Types
In order to use this library, you will need to import and install driver
libraries for key types you'll be working with via the use() method.
To use the library with one or more supported suites:
import {Ed25519VerificationKey2020} from '@digitalbazaar/ed25519-verification-key-2020';
import {X25519KeyAgreementKey2020} from '@digitalbazaar/x25519-key-agreement-key-2020';
import {CryptoLD} from 'crypto-ld';
const cryptoLd = new CryptoLD();
cryptoLd.use(Ed25519VerificationKey2020);
cryptoLd.use(X25519KeyAgreementKey2020);
const edKeyPair = await cryptoLd.generate({type: 'Ed25519VerificationKey2020'});Generating a new public/private key pair
To generate a new public/private key pair: cryptoLd.generate(options):
{string} [type]Suite name, required.{string} [controller]Optional controller URI or DID to initialize the generated key. (This will also init the key id.){string} [seed]Optional deterministic seed value (only supported by some key types, such ased25519) from which to generate the key.
Importing a key pair from storage
To create an instance of a public/private key pair from data imported from
storage, use cryptoLd.from():
const serializedKeyPair = { ... };
const keyPair = await cryptoLd.from(serializedKeyPair);Note that only installed key types are supported, if you try to create a
key pair via from() for an unsupported type, an error will be thrown.
Common individual key pair operations
The full range of operations will depend on key type. Here are some common operations supported by all key types.
Exporting the public key only
To export just the public key of a pair - use export():
keyPair.export({publicKey: true});
// ->
{
type: 'Ed25519VerificationKey2020',
id: 'did:example:1234#z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3',
controller: 'did:example:1234',
publicKeyMultibase: 'zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf'
}Exporting the full public-private key pair
To export the full key pair, including private key (warning: this should be a carefully considered operation, best left to dedicated Key Management Systems):
keyPair.export({publicKey: true, privateKey: true});
// ->
{
type: 'Ed25519VerificationKey2020',
id: 'did:example:1234#z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3',
controller: 'did:example:1234',
publicKeyMultibase: 'zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf',
privateKeyMultibase: 'z4E7Q4neNHwv3pXUNzUjzc6TTYspqn9Aw6vakpRKpbVrCzwKWD4hQDHnxuhfrTaMjnR8BTp9NeUvJiwJoSUM6xHAZ'
}Generating and verifying key fingerprint
To generate a fingerprint:
keyPair.fingerprint();
// ->
'z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3'To verify a fingerprint:
keyPair.verifyFingerprint({
fingerprint: 'z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3'
});
// ->
{ valid: true }Operations on signature-related key pairs
For key pairs that are related to signature and verification (that extend from
the LDVerifierKeyPair class), two additional operations must be supported:
Creating a signer function
In order to perform a cryptographic signature, you need to create a sign
function, and then invoke it.
const keyPair = await cryptoLd.generate({type: 'Ed25519VerificationKey2020'});
const {sign} = keyPair.signer();
const data = 'test data to sign';
const signatureValue = await sign({data});Creating a verifier function
In order to verify a cryptographic signature, you need to create a verify
function, and then invoke it (passing it the data to verify, and the signature).
const keyPair = await cryptoLd.generate({type: 'Ed25519VerificationKey2020'});
const {verify} = keyPair.verifier();
const {valid} = await verify({data, signature});Contribute
See the contribute file!
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
New BSD License (3-clause) © Digital Bazaar