shamir secret sharing demo in js

shamir-demo.js

const secrets = require('secrets.js-grempe')

const shamir = {
	create: (plainText, totalShares, threshold) => {
		// convert the text into a hex string
		var pwHex = secrets.str2hex(passphrase); // => hex string

		// split into 2 shares with a threshold of 2.
		// 1 share will be sent to backend and stored there
		// and another share will be kept by the user.
		var shares = secrets.share(pwHex, 2, 2);

		return shares
	},
	decode: (arrayOfShares, plainText) => {
		const sharesCombined = secrets.combine(arrayOfShares);

		//convert back to UTF string and compare to plainText
		return secrets.hex2str(sharesCombined)
	}
}

// a 10-word passphrase.
// the longer the passphrase the longer each shamir's share will be.
const passphrase = 'shifted patent embassy minimum heritage shifted patent embassy minimum heritage';
const shamirShares = shamir.create(passphrase, 2, 2)

console.log('- shamir shares:\n', shamirShares)
console.log('- shamir shares decoded:', shamir.decode(shamirShares)); // => true
console.log('- shamir shares verification:', shamir.decode(shamirShares) === passphrase); // => true

// output:
// - shamir shares:
//  [ '801242eb5c278b117be76675cbfa38b4e108b87385ec8d940d05c353e7c1f44565d5565f86d59006e0130c7963a69205843c31980d4affe9a558751e3fb669e0de735ef0b79bba9446ab4819aae7d55e229b6d3d575fd706df242fb049d796fe3cc65762809a034d81099cead3f8d7b662fd6674331ae31ff81f36121fe75a1b1b922f663153706df45faeaf755036331576bff49fd13970f7c70337e8f9bce50dd',
//   '802485f7736f0d62ec2ec52b8d85b9d9c8f0bab70dc8d188022b8dd7c433e3aac01aa7dedbab28bdc97600631d7d2e6b0319b9d1dd5437d2918130ddb77cc821a436aa3165e6be0884875b529fafa12d9c771dbb745e749da5a8477089cf248db2aca5450725ddfadbf2f3647c50744cce5b179860241e9e38afb574242eaf97fd8445ec64a6e90a338e966f3360665623ed683924b269c1e64e0ccfcb82b39a032' ]
// - shamir shares decoded: shifted patent embassy minimum heritage shifted patent embassy minimum heritage
// - shamir shares verification: true