Dave's Data

Introduction In the wake of Bitcoin's success, many "alternative" cryptocurrencies, or "alt-coins" have emerged that change various aspects of the coin in an attempt to improve upon Bitcoin.  (We'll ignore the many that have emerged with the goal of simply duplicating it to put money in their creators' pockets). I've been particularly interested in variants that change something with the "proof-of-work" function.  This sits at the heart of Bitcoin's decentralization:  If a node in the Bitcoin network wishes to be the one permitted to sign a block of transactions, and receive payment for doing so, it must prove that it did a certain amount of computational effort.  This mechanism spreads the authority for the transaction history over all of the participants in the protocol in rough proportion to their computational horsepower.  The goal of this mechanism is to ensure that no one entity can control the currency without spending an eno...

I've continued to stay interested in alt-currencies, and, recently, a new one caught my eye:   Riecoin .  Named after Riemann, the proof-of-work in this currency is finding dense clusters of primes starting at a number n , where there are six primes "in a row":   n, n+4, n+6, n+10, n+12 , and n+16 .   To solve a block, you do some hashing of the block contents just as in Bitcoin, and use it to generate a "target" number.  The proof-of-work is then to find a prime chain within a certain numerical distance above the target number. I plan on a more technical post about the process of optimizing the search for these (you can see some discussion of it on the Riecoin bitcointalk thread if you really want).  It's quite fun, but at this point, it still boils down to relatively straightforward prime sieving for huge numbers (1200-1300 bits). There's one very important thing to understand about such sequences, though, before going further:  They only appear ...