比特币生态系统探秘

    2013年，比特币的表现继续让人大开眼界，就算11月末它开始大跌之后，仍然精彩不减——如果按照12月18日530美元的价格，在1月份以13美元买入的比特币回报率超过了4,000%。比特币价格飙升还引爆了另一轮热潮：今年先后涌现出100多种“替代币”，它们都是各种社区模仿比特币用代码攒出来的，名字也千奇百怪，比如什么Nova币、Zeta币、Bitbar、Cryptogenic Bullion、BBQ币，哦对了，还有Sex币。其中有些对比特币的技术做了小幅、有意义的改进，但多数都是赤裸裸的抄袭——很大一部分干脆就是一种诈骗手段，纯粹是想利用加密数字货币支持者的热情发笔横财。

    不过，这些货币仍然是比特币发展史的重要组成部分，其中有一些还可能在未来获得应用，其中就包括加密数字货币，这是一种主要使用加密技术制造的数字货币。就算近期由于比特币价格大跌拖累很多替代币的价值跟着下挫，还有五种替代币各自市值均超过一千万美元，另外20种每种超过一百万美元，还有一些被恰当地称为“垃圾币”的，当前市值也有约75,000美元。安德里亚斯•M. 安托诺坡罗斯是几个涉及比特币业务的初创企业的咨询师。他写了一本即将出版的比特币技术专著，也是知名播客“话说比特币”（Let's Talk Bitcoin）的主持人。他把当前这种情况称为“加密数字货币生态系统”。

    这个生态学比喻与进化逻辑有一部分关系。安托诺坡罗斯称：“替代币有两个目的。首先，它们是用来测试新技术的，看看这些技术是否可行，以及市场是否接受。”这些新技术主要围绕比特币挖掘算法的不同形式展开——这种算法是一种“工作量证明”（proof of work，指系统为达到某目标而设置的工作度量方法，最初被应用在网络的拒绝服务识别和反垃圾邮件上——译注）的问题解决技术，它能保护流通的货币及其交易记录。这些采用不同技术的货币包括：允许一种货币由不同于比特币的设备处理的（Lite币，目前市值为3.3亿美元），声称使用能量更少的（Peer币，市值4700万美元），以及能提供更快交易确认时间的（这种货币有很多，比如市值500万美元的Feather币）。其他加密数字货币则宣称使用了更加特殊的技术，比如Frei币（市值两百万美元）内置了滞期费，如果它仅仅持有却不用于消费的话，就会失去价值。甚至还有一种货币用工作量证明算法来寻找新质数（这种货币的名字当然就叫Prime币，现在市值六百万美元）。安托诺坡罗斯称，这些技术特性在接受某种替代币“测试”后如果证明富有吸引力、而且可以实现兼容，它就有希望被纳入比特币的范畴。

    不过似乎没人认为这些替代币会取代比特币，成为一统天下的加密数字货币。正如近期美国银行（Bank of America）的一份报告所指出的，比特币的统治地位主要是由网络效应来保障的：它的价值是由超大规模和挖矿群体、服务提供商、用户及商家所投入的资本赋予的。如果没有比特币的规模及网络的力量，许多替代币随着它们依附的网络被抛弃或被黑客攻破，都会销声匿迹——安托诺坡罗斯称替代币的第二个目的就在于，“展示触目惊心的失败模式”，而它失败的教训将使幸存者更加强大。

    Bitcoin's 2013 remains impressive, even after the digital currency has taken a serious tumble since late November – at the December 18th price of $530, a Bitcoin purchased for $13 in January would return over 4,000%. Another explosion has tracked that price's: the emergence this year of 100 or more "altcoins," collections of code and community modeled after bitcoin and with names like Novacoin, Zetacoin, Bitbar, Cryptogenic Bullion, BBQCoin and, yes, Sexcoin. Some offer minor but meaningful variations on bitcoin's technology, while most are outright copies – and a huge proportion are fraud schemes preying on the enthusiasm of cryptocurrency supporters.

    Still, these coins are an important part of the story of bitcoin, and some are likely to be part of any future that includes cryptocurrency, a type of digital currency that depends on cryptography. Even after the recent bitcoin decline took many altcoin valuations down with it, there are five altcoins with market capitalizations of over $10 million each, another 20 of over $1 million each, and dozens of others ranging down to the aptly named "junkcoin," with a current market cap of about $75,000. Andreas M. Antonopoulos, a consultant on several bitcoin-related startup projects, author of a forthcoming technical volume on bitcoin, and host of the popular "Let's Talk Bitcoin" podcast, describes this landscape as the "crypto-currency ecosystem."

    The ecological metaphor hinges in part on an evolutionary logic. "Altcoins serve two purposes," Antonopoulos says. "First, they test new tech features, showing whether they work and whether the market will accept them." Those new features mostly revolve around variations on bitcoin's mining algorithm – the "proof of work" problem-solving that secures a distributed currency and its transaction records. Variations include those allowing a currency to be processed by different equipment than bitcoin (Litecoin, current market cap $330 million), those purporting to use less energy (Peercoin, $47 million), and those that offer faster transaction confirmation times (many, among them Feathercoin, $5 million). Other cryptocoins claim more idiosyncratic variations, such as the demurrage built into Freicoin ($2 million), which loses value if it is held without being spent. There's even a currency that uses its proof-of-work algorithm to search for new prime numbers (that currency is named, of course, Primecoin, $6 million). Those features that prove attractive and compatible after 'testing' by an altcoin, Antonopoulos says, will likely be incorporated into Bitcoin.

    No one seems to foresee any of the altcoins displacing bitcoin as the dominant cryptocurrency. As a recent Bank of America report pointed out, bitcoin's dominance is guaranteed above all by the network effect: the value imparted by the huge size and capital investment of its community of miners, service providers, users, and merchants. Without bitcoin's volume and network strength, many of the altcoins will disappear, as their networks are abandoned or overwhelmed by hackers – Antonopoulos says the second purpose of altcoins is to "demonstrate spectacular failure modes" whose lessons will strengthen the survivors.