(Short Paper) Towards More Reliable Bitcoin Timestamps

TL;DR

This paper introduces a mechanism to enhance the reliability of Bitcoin timestamps, enabling proof of block creation within specific time ranges, using existing SSL/TLS servers as reference sources.

Contribution

It presents a simple, efficient, and backward-compatible protocol that improves Bitcoin timestamp trustworthiness and can detect protocol attacks.

Findings

Provides evidence for block creation time ranges

Utilizes existing SSL/TLS servers as reference sources

Detects attacks against Bitcoin protocol

Abstract

Bitcoin provides freshness properties by forming a blockchain where each block is associated with its timestamp and the previous block. Due to these properties, the Bitcoin protocol is being used as a decentralized, trusted, and secure timestamping service. Although Bitcoin participants which create new blocks cannot modify their order, they can manipulate timestamps almost undetected. This undermines the Bitcoin protocol as a reliable timestamping service. In particular, a newcomer that synchronizes the entire blockchain has a little guarantee about timestamps of all blocks. In this paper, we present a simple yet powerful mechanism that increases the reliability of Bitcoin timestamps. Our protocol can provide evidence that a block was created within a certain time range. The protocol is efficient, backward compatible, and surprisingly, currently deployed SSL/TLS servers can act as reference time sources. The protocol has many applications and can be used for detecting various attacks against the Bitcoin protocol.