From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id DE494C0176 for ; Sun, 24 May 2020 01:12:14 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id C60D187A3D for ; Sun, 24 May 2020 01:12:14 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id sOi5r0ZfPNGH for ; Sun, 24 May 2020 01:12:12 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-40141.protonmail.ch (mail-40141.protonmail.ch [185.70.40.141]) by whitealder.osuosl.org (Postfix) with ESMTPS id 4893287A18 for ; Sun, 24 May 2020 01:12:12 +0000 (UTC) Date: Sun, 24 May 2020 01:12:04 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail; t=1590282729; bh=AJwREk36X4yVpuzp0sjVS8Aez2q0WGQWwaWcJcOyEYk=; h=Date:To:From:Reply-To:Subject:In-Reply-To:References:From; b=CwjRqF62E9lJEtWseCtPHim39xb3AE3C1abr82ELqzvGl8RHYaoEDbwdmYc3T1W0x Dnyzj30+26xcfgLAAZ3lXVA0KL6q6dCOknuLR2oK7vj5m0+TKdz/ZFbuMFdpT2oeok fyHvX1FS2ptW25LZaqFgOIcZoRe5Hwwdk1M3HBNE= To: Karl , Bitcoin Protocol Discussion From: ZmnSCPxj Reply-To: ZmnSCPxj Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [bitcoin-dev] hashcash-newhash X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 24 May 2020 01:12:15 -0000 Good morning Karl, > Hi, > > I'd like to revisit the discussion of the digest algorithm used in hashca= sh. > > I believe migrating to new hashing algorithms as a policy would significa= ntly increase decentralization and hence security. Why do you believe so? My understanding is that there are effectively two strategies for ensuring = decentralization based on hash algorithm: * Keep changing the hash algorithm to prevent development of ASICs and ensu= re commodity generic computation devices (GPUs) are the only practical targ= et. * Do not change the algorithm, to ensure that knowledge of how best to impl= ement an ASIC for the algorithm becomes spread out (through corporate espio= nage, ASIC reverse-engineering, patent expiry, and sheer engineering effort= ) and ASICs for the algorithm are as commoditized as GPUs. The former strategy has the following practical disadvantages: * Developing new hash algorithms is not cheap. The changes to the hashcash algorithm may need to occur faster than the s= peed at which we can practically develop new, cryptographically-secure hash= algorithms. * It requires coordinated hardforks over the entire network at an alarmingl= y high rate. * It arguably puts too much power to the developers of the code. On the other hand, the latter strategy requires us only to survive an inter= mediate period where ASICs are developed, but not yet commoditized; and dur= ing this intermediate period, the centralization pressure of ASICs might no= t be more powerful than other centralization pressures -- Which brings us to another point. Non-ASIC-resistance is, by my understanding, a non-issue. Regardless of whether the most efficient available computing substrate for = the hashcash algorithm is CPU, GPU, or ASIC, ultimately miner earnings are = determined by cost of power supply. Even if you imagine that changing the hashcash algorithm would make CPUs pr= actical again, you will still not run it on the CPU of a mobile, because a = mobile runs on battery, and charging a battery takes more power than what y= ou can extract from the battery afterwards, because thermodynamics. Similarly, geographic locations with significant costs of electrical power = will still not be practical places to start a mine, regardless if the mine = is composed of commodity server racks, commodity video cards, or commodity = ASICs. If you want to solve the issue of miner centralization, the real solution i= s improving the efficiency of energy transfer to increase the areas where c= heap energy is available, not stopgap change-the-algorithm-every-6-months. Regards, ZmnSCPxj > > I believe the impact on existing miners could be made pleasant by gradual= ly moving the block reward from the previous hash to the next (such that bo= th are accepted with different rewards).=C2=A0 An appropriate rate could po= ssibly be calculated from the difficulty. > > You could develop the frequency of introduction of new hashes such that o= nce present-day ASICs are effectively obsolete anyway due to competition, n= ew ones do not have time to develop. > > I'm interested in hearing thoughts and concerns. > > Karl Semich