tweetsodium/dist/index.umd.js

libsodium sealed cryptobox using tweetnacl

(function (global, factory) {
  if (typeof define === "function" && define.amd) {
    define(["tweetnacl", "blakejs"], factory);
  } else if (typeof exports !== "undefined") {
    factory(require("tweetnacl"), require("blakejs"));
  } else {
    var mod = {
      exports: {}
    };
    factory(global.tweetnacl, global.blakejs);
    global.index = mod.exports;
  }
})(this, function (_tweetnacl, _blakejs) {
  'use strict';

  _tweetnacl = _interopRequireDefault(_tweetnacl);

  function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

  var tweetSodium = module.exports;
  // Authenticated sealing only prepends the nonce to the ciphertext. Anonymous
  // sealing also prepends a random public key.
  tweetSodium.overheadLength = _tweetnacl.default.box.overheadLength + _tweetnacl.default.box.publicKeyLength; // Generates a 24 byte nonce that is a blake2b digest of the ephemeral
  // public key and the reipient's public key.
  //
  // Returns a 24-byte Uint8Array
  //
  // Parameters:
  // - epk - ephemeral public key Uint8Array
  // - publicKey - recipient's public key Uint8Array

  function sealNonce(epk, publicKey) {
    var hash = (0, _blakejs.blake2bInit)(_tweetnacl.default.box.nonceLength, false);
    (0, _blakejs.blake2bUpdate)(hash, epk);
    (0, _blakejs.blake2bUpdate)(hash, publicKey);
    return (0, _blakejs.blake2bFinal)(hash);
  } // Encrypt a message for a recipient.
  //
  // Returns a Uint8Array whose length is 48 bytes greater than the message's.
  //
  // Parameters:
  // - message - message Uint8Array to encrypt.
  // - publicKey - recipient's public key Uint8Array.


  tweetSodium.seal = function (message, publicKey) {
    var ekp = _tweetnacl.default.box.keyPair();

    var out = new Uint8Array(message.length + tweetSodium.overheadLength);
    out.set(ekp.publicKey, 0);
    var nonce = sealNonce(ekp.publicKey, publicKey);

    var ct = _tweetnacl.default.box(message, nonce, publicKey, ekp.secretKey);

    out.set(ct, _tweetnacl.default.box.publicKeyLength);
    return out;
  }; // Decrypt the ciphertext message using the secret key.
  //
  // Returns a Uint8Array whose length is 48 bytes less than the ciphertext's.
  //
  // Parameters:
  // - ciphertext - encrypted message Uint8Array.
  // - secretKey - secret key Uint8Array.


  tweetSodium.sealOpen = function (ciphertext, publicKey, secretKey) {
    var epk = ciphertext.slice(0, _tweetnacl.default.box.publicKeyLength);
    var nonce = sealNonce(epk, publicKey);
    ciphertext = ciphertext.slice(_tweetnacl.default.box.publicKeyLength);
    return _tweetnacl.default.box.open(ciphertext, nonce, epk, secretKey);
  };
});