supersphincs

Overview

SuperSPHINCS combines the post-quantum SPHINCS+ with the more conventional elliptic-curve (ECC) Ed25519 as a single signing scheme. SPHINCS+ is provided by sphincs and Ed25519 signing is performed using libsodium.js.

Before signing, a SHA-512 hash is performed, using the current platform's native implementation where available or an efficient JavaScript implementation from TweetNaCl.js otherwise.

Example Usage

import {superSphincs} from 'supersphincs';

const keyPair /*: {privateKey: Uint8Array; publicKey: Uint8Array} */ =
    await superSphincs.keyPair()
;

const message /*: Uint8Array */ =
    new Uint8Array([104, 101, 108, 108, 111]) // "hello"
;

// Optional additional data argument, similar conceptually to what AEAD cyphers support.
// If specified, must be the same when signing and verifying. For more information and
// usage advice, see: https://download.libsodium.org/doc/secret-key_cryptography/aead.html
const additionalData /*: Uint8Array */ =
    new Uint8Array([119, 111, 114, 108, 100]) // "world"
;

/* Combined signatures */

const signed /*: Uint8Array */ =
    await superSphincs.sign(message, keyPair.privateKey, additionalData)
;

const verified /*: Uint8Array */ =
    await superSphincs.open(signed, keyPair.publicKey, additionalData) // same as message
;

/* Detached signatures */

const signature /*: Uint8Array */ =
    await superSphincs.signDetached(message, keyPair.privateKey, additionalData)
;

const isValid /*: boolean */ =
    await superSphincs.verifyDetached(
        signature,
        message,
        keyPair.publicKey,
        additionalData
    ) // true
;

/* Export and optionally encrypt keys */

const keyData /*: {
    private: {
        classical: string;
        combined: string;
        postQuantum: string;
    };
    public: {
        classical: string;
        combined: string;
        postQuantum: string;
    };
} */ =
    await superSphincs.exportKeys(keyPair, 'secret passphrase')
;

if (typeof localStorage === 'undefined') {
    localStorage    = {};
}

// May now save exported keys to disk (or whatever)
localStorage.superSphincsPrivateKey = keyData.private.combined;
localStorage.sphincsPrivateKey      = keyData.private.postQuantum;
localStorage.eccPrivateKey          = keyData.private.classical;
localStorage.superSphincsPublicKey  = keyData.public.combined;
localStorage.sphincsPublicKey       = keyData.public.postQuantum;
localStorage.eccPublicKey           = keyData.public.classical;


/* Reconstruct an exported key using either the superSphincs
    value or any pair of valid sphincs and ecc values */

const keyPair1 = await superSphincs.importKeys({
    public: {
        classical: localStorage.eccPublicKey,
        postQuantum: localStorage.sphincsPublicKey
    }
});

// May now use keyPair1.publicKey as in the above examples
console.log('Import #1:');
console.log(keyPair1);

const keyPair2 = await superSphincs.importKeys(
    {
        private: {
            combined: localStorage.superSphincsPrivateKey
        }
    },
    'secret passphrase'
);

// May now use keyPair2 as in the above examples
console.log('Import #2:');
console.log(keyPair2);

// Constructing an entirely new SuperSPHINCS key pair from
// the original SPHINCS+ key pair and a new ECC key pair
const keyPair3 = await superSphincs.importKeys(
    {
        private: {
            classical: (
                await superSphincs.exportKeys(
                    await superSphincs.keyPair(),
                    'hunter2'
                )
            ).private.classical,
            postQuantum: localStorage.sphincsPrivateKey
        }
    },
    {
        classical: 'hunter2',
        postQuantum: 'secret passphrase'
    }
);

// May now use keyPair3 as in the above examples
console.log('Import #3:');
console.log(keyPair3);

Changelog

Breaking changes in major versions:

8.0.0:

• Standardized method signatures across packages.

7.0.0:

• Upgraded from SPHINCS and RSA to SPHINCS+ and ECC. For backwards compatibility with previous versions of this package, use supersphincs-legacy.

6.0.0:

• Additional data optional with default value of new Uint8Array(0).

5.0.0:

• Additional data format change.

4.0.0:

• As part of upgrading from asm.js to WebAssembly (with asm.js included as a fallback), the API is fully asynchronous.

3.0.0:

• General API cleanup.

2.0.0:

• Split into module (supersphincs.js) and standalone pre-bundled version (dist/supersphincs.js).