format.js

// SPDX-FileCopyrightText: 2022 Andre 'Staltz' Medeiros
//
// SPDX-License-Identifier: LGPL-3.0-only

const sodium = require('chloride');
const privateBox = require('private-box');
const Ref = require('ssb-ref');
const {
  isButtwooV1FeedSSBURI,
  isBendyButtV1FeedSSBURI,
  decompose,
  isClassicFeedSSBURI,
} = require('ssb-uri2');

const encryptionFormat = {
  name: 'box',

  encrypt(plaintextBuf, opts) {
    const encryptionKeys = opts.recps
      .map(function convertToBase64DataStr(recp) {
        if (Ref.isFeed(recp)) return recp.slice(1, -8);
        else if (
          isClassicFeedSSBURI(recp) ||
          isBendyButtV1FeedSSBURI(recp) ||
          isButtwooV1FeedSSBURI(recp)
        )
          return decompose(recp).data;
        else if (recp && typeof recp === 'string') {
          // prettier-ignore
          throw new Error('encryption format "box" does not support recipient "' + recp + '"');
        } else return null;
      })
      .filter((maybeBase64DataStr) => !!maybeBase64DataStr)
      .map((base64DataStr) => Buffer.from(base64DataStr, 'base64'))
      .map(sodium.crypto_sign_ed25519_pk_to_curve25519);

    return privateBox.multibox(plaintextBuf, encryptionKeys);
  },

  decrypt(ciphertextBuf, opts) {
    const secretKey =
      opts.keys._exchangeKey || // use the cache
      sodium.crypto_sign_ed25519_sk_to_curve25519(
        Buffer.from(opts.keys.private, 'base64'),
      );
    if (opts.keys.private) opts.keys._exchangeKey = secretKey; // set the cache
    return privateBox.multibox_open(ciphertextBuf, secretKey);
  },
};

module.exports = encryptionFormat;