nonce()

in src/recordlayer.js [98:112]

• 10 lines of code
• 2 McCabe index (conditional complexity)

  nonce() {
    // Ref https://tools.ietf.org/html/rfc8446#section-5.3:
    // * left-pad the sequence number with zeros to IV_LENGTH
    // * xor with the provided iv
    // Our sequence numbers are always less than 2^24, so fit in a Uint32
    // in the last 4 bytes of the nonce.
    const nonce = this.iv.slice();
    const dv = new DataView(nonce.buffer, nonce.byteLength - 4, 4);
    dv.setUint32(0, dv.getUint32(0) ^ this.seqnum);
    this.seqnum += 1;
    if (this.seqnum > MAX_SEQUENCE_NUMBER) {
      throw new TLSError(ALERT_DESCRIPTION.INTERNAL_ERROR);
    }
    return nonce;
  }