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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | 1x 314x 313x 312x 311x 310x 309x 308x 307x 158x 149x 910x 1x | /**
* @file Secret Sharing
* @copyright Multifactor, Inc. 2022–2025
*
* @description
* Divide a secret into shares using various methods
*
* @author Vivek Nair (https://nair.me) <vivek@nair.me>
*/
const sss = require('./library')
/**
* K-of-N secret sharing. Uses direct secret sharing for K = 1, and Shamir's Secret Sharing for K > 1.
*
* @example
* // share secret using 2-of-3 shares
* const shares = mfkdf.secrets.share(Buffer.from('abcdefghijklmnopqrst'), 2, 3) // -> [Buffer, Buffer, Buffer]
*
* // recover secret using 2 shares
* const secret = mfkdf.secrets.combine([shares[0], null, shares[2]], 2, 3)
* secret.toString() // -> hello world
*
* // recover original 3 shares
* const recover = mfkdf.secrets.recover([shares[0], null, shares[2]], 2, 3) // -> [Buffer, Buffer, Buffer]
*
* @param {Buffer} secret - The secret value to be shared
* @param {number} k - The threshold of shares required to reconstruct the secret
* @param {number} n - The number of shares to generate
* @returns {Array.<Buffer>} An array of N shares as Buffers
* @author Vivek Nair (https://nair.me) <vivek@nair.me>
* @since 0.8.0
* @memberOf secrets
*/
function share (secret, k, n) {
if (!Buffer.isBuffer(secret)) throw new TypeError('secret must be a buffer')
if (secret.length === 0) throw new RangeError('secret must not be empty')
if (!Number.isInteger(n)) throw new TypeError('n must be an integer')
if (!(n > 0)) throw new RangeError('n must be positive')
if (!Number.isInteger(k)) throw new TypeError('k must be an integer')
if (!(k > 0)) throw new RangeError('k must be positive')
if (k > n) throw new RangeError('k must be less than or equal to n')
if (k === 1) {
// 1-of-n
return Array(n).fill(secret)
} else {
// k-of-n
const shares = sss.split(new Uint8Array(secret), n, k)
return shares.map((share) => Buffer.from(share))
}
}
module.exports.share = share
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