Hashed Time-Locked Contracts (HTLCs) are a widely used primitive in blockchain systems for such applications as payment channels, atomic swaps, and so on. Unfortunately, HTLC is incentive-incompatible and is vulnerable to bribery attacks. MAD-HTLC is an elegant solution aiming to address the incentive incompatibility of HTLC. In this talk, Kartik Nayak (Duke University) shows that MAD-HTLC is also incentive-incompatible. But beyond that, Kartik goes on to demonstrate the importance of considering actively rational behaviors by showing three novel reverse-bribery attacks against MAD-HTLC that can be implemented using Trusted Execution Environments. He also shows that reverse bribery can be combined with original delaying attacks to render MAD-HTLC insecure regardless of the relationship between collateral and deposits made in the contract. Based on these findings, he devises a new lightweight smart contract specification, He-HTLC, that meets the HTLC specification even in the presence of actively rational miners.
The views expressed here are those of the individual AH Capital Management, L.L.C. (“a16z”) personnel quoted and are not the views of a16z or its affiliates. Certain information contained in here has been obtained from third-party sources, including from portfolio companies of funds managed by a16z. While taken from sources believed to be reliable, a16z has not independently verified such information and makes no representations about the current or enduring accuracy of the information or its appropriateness for a given situation. In addition, this content may include third-party advertisements; a16z has not reviewed such advertisements and does not endorse any advertising content contained therein.
This content is provided for informational purposes only, and should not be relied upon as legal, business, investment, or tax advice. You should consult your own advisers as to those matters. References to any securities or digital assets are for illustrative purposes only, and do not constitute an investment recommendation or offer to provide investment advisory services. Furthermore, this content is not directed at nor intended for use by any investors or prospective investors, and may not under any circumstances be relied upon when making a decision to invest in any fund managed by a16z. (An offering to invest in an a16z fund will be made only by the private placement memorandum, subscription agreement, and other relevant documentation of any such fund and should be read in their entirety.) Any investments or portfolio companies mentioned, referred to, or described are not representative of all investments in vehicles managed by a16z, and there can be no assurance that the investments will be profitable or that other investments made in the future will have similar characteristics or results. A list of investments made by funds managed by Andreessen Horowitz (excluding investments for which the issuer has not provided permission for a16z to disclose publicly as well as unannounced investments in publicly traded digital assets) is available at https://a16z.com/investments/.
Charts and graphs provided within are for informational purposes solely and should not be relied upon when making any investment decision. Past performance is not indicative of future results. The content speaks only as of the date indicated. Any projections, estimates, forecasts, targets, prospects, and/or opinions expressed in these materials are subject to change without notice and may differ or be contrary to opinions expressed by others. Please see https://a16z.com/disclosures for additional important information.