export() {
    $.checkState(this.#round > 0, 'Cannot export a session that has not started');
    $.checkState(!this.isKeyChainReady(), 'Cannot export a completed session. The keychain is ready with getKeyChain()');
    const chainCodeCommitment = this.#dkg.chainCodeCommitment;
    const sessionBytes = this.#dkg.dkgSessionBytes || this.#dkg.dkgSession?.toBytes();
    const payload = this.#round +
      ':' + this.#partySize +
      ':' + this.#minSigners +
      ':' + this.#partyId +
      ':' + Buffer.from(sessionBytes).toString('base64') +
      ':' + Buffer.from(chainCodeCommitment || []).toString('base64');
    const buf = encrypt(Buffer.from(payload, 'utf8'), this.#authKey.publicKey, this.#authKey);
    return buf.toString('base64');
  }
Export the keygen session to a base64 encoded string
@returns {string} Base64 encoded session string