Narcissistic Passion Minified

    shamir-tss-gf256

    0.5.0 • Public • Published

    Shamir Threshold Secret Sharing using Galois Field 2^8

    Uses Shamir's secret sharing method to allows space-efficient secret sharing (splitting) requiring a minimum threshold of shares in order to unlock the original secret.

    Example

    import * as shamir_tss from 'shamir-tss-gf256'
    // or const shamir_tss = require('shamir-tss-gf256')
    // or <script src='https://unpkg.com/shamir-tss-gf256@0.4.0/umd/shamir-tss-gf256.min.js' ></script>
     
    const secret = shamir_tss.randomBytes(16) // or any Uint8Array/Buffer
     
    // split into 10 shares, allowing any 3 to unlock the secret
    const shares = shamir_tss.generateShares_b64(secret, 3, 10)
    // shares = [
    //   'AwH9nHA-35qs4JvF8qkfngTK',
    //   'AwI3E71t-b3c2odZ_2pNcT-3',
    //   'AwO1ZJY6wtOKODOfme1m1wP0',
    //   'AwSoWHr_aQSotSWu6Pl60tEj',
    //   'AwUqL1GoUmr-V5Fojn5RdO1g',
    //   'AwbgoJz7dE2ObY30g70Dm9Yd',
    //   'Awdi17esTyPYjzky5TooPepe',
    //   'AwjN7ewQD5wmByQm8vxuDECz',
    //   'AwlPmsdHNPJw5ZDglHtFqnzw',
    //   'AwqFFQoUEtUA34x8mbgXRUeN' ]
     
     
    const res_under_a = shamir_tss.unlockShares([shares[2], shares[7]], false)
    // res_under_a = false
     
    try {
      const res_under = shamir_tss.unlockShares([shares[2], shares[7]])
    } catch (err) {
      // Number of shares did not meet threshold to unlock shared secret. (2 of 3, 0 duplicates)
    }
     
     
    const res_min = shamir_tss.unlockShares([shares[2], shares[7], shares[4]])
    // res_min = Uint8Array [ 127, 235, 91, 105, 228, 244, 250, 2, 47, 3, 148, 46, 52, 56, 56, 137 ]
     
    const res_over = shamir_tss.unlockShares([shares[2], shares[7], shares[4], shares[9], shares[1]])
    // res_over = Uint8Array [ 127, 235, 91, 105, 228, 244, 250, 2, 47, 3, 148, 46, 52, 56, 56, 137 ]
     

    API

    Primary

    generateShares(secret, thresholdShares, totalShares)

    Transforms secret into a Galois Field polynomial according to Shamir's secret sharing method, returning the specified number of totalShares where any unique subset of thresholdShare shares will unlock the original secret.

    Returns the shares as array of Uint8Array.

    generatorShares(secret, thresholdShares, [totalShares])

    generateShares() returning an iterator of Uint8Array shares.

    unlockShares(shares, [valueIfUnderThreshold])

    Computes and returns the secret using provided shares array, given sufficient number of shares. Otherwise, valueIfUnderThreshold is returned.

    Cautionary Note: There are no self-consistency checks built into Shamir Threshold Secret Shares -- combining shares from different source will result in unlocking some undefined "secret".

    generateShares_b64(secret, thresholdShares, totalShares)

    generateShares() returning an array of Base64 encoded shares.

    generatorShares_b64(secret, thresholdShares, [totalShares])

    generateShares() returning an iterator of Base64 encoded shares.

    unlockShares_b64(shares, [valueIfUnderThreshold])

    unlockShares() with result Base64 encoded.

    Utilities

    isBinarySecret(arg)

    True if arg is a Buffer or Uint8Array, false otherwise.

    randomBytes(n_bytes)

    In Browser environments, generates a Uint8Array of specified byte length using crypto.getRandomValues().

    In NodeJS, generates a Uint8Array of specified byte length using crypto.randomBytes().

    u8_to_base64(u8)

    Converts a Uint8Array or Buffer to a Base64 (URL safe) encoded string.

    base64_to_u8(string_b64)

    Converts a Base64 encoded string to a Uint8Array or Buffer.

    Internal API

    The internal class ShamirSecretShare (alias ShamirTSS) is exposed. Please read the source for understanding and details.

    Galois Field 256 (2^8) math primitives

    function compute_poly(x, poly_coeff) {}
    function lagrange_basis_poly_at_zero(u) {}
    function lagrange_interpolate(u, v_iterable) {}
     
    function add(x, y) {}
    function mul(x, y) {}
    function div(x, y) {}

    To use:

    const gf256 = require('shamir-tss-gf256/cjs/gf256')
    // or import * as gf256 from 'shamir-tss-gf256/esm/gf256'
    // or <script src='https://unpkg.com/shamir-tss-gf256@0.4.0/umd/gf256.js' ></script>

    License

    ISC

    Install

    npm i shamir-tss-gf256

    DownloadsWeekly Downloads

    9

    Version

    0.5.0

    License

    BSD-2-Clause

    Unpacked Size

    161 kB

    Total Files

    26

    Last publish

    Collaborators

    • shanewholloway