Let me state it like this: A month ago I had no clue about prime numbers and related algorithms. We took Supercomputing's miner and started to understand the basics (how does the sieve work, how is it parameterized). We eventually succeeded putting the sieve on the GPU and making it fast. What I like a lot about CoinShield is how the Proof of Work validation algorithm accepts all kinds of different prime constellations. You are not forced to search for [4 2 4 2 4] inter-prime distance patterns like in RieCoin.

As a side project we also started looking into bignum maths for integers and modular arithmetics. We implemented some fundamental 1024 bit GPU maths functions from scratch as there was not really a lot of GPU bignum code out there. Our first attempt at doing modular exponentiation worked eventually, but it was so much slower than the CPU. Sometimes algorithms matter more than code efficiency or hardware capabilities. Then we started looking into Montgomery multiplication/exponentiation and succeeded making it work reasonably well. We still have to use a hybrid CPU/GPU approach for best results.

Now we are at a point where we think we could pull off a Riecoin GPU miner - and also finding record breaking 6-tuples on the GPU is within reach and you could find a 6-tuple for a 616 decimal digit prime number. All you need is fast 2048 bit integer arithmetics and a decent sieve.

It certainly helps to have a partner in crime when doing fun projects like this because you keep motivating each other with new concepts and ideas to try out. Also the 4 eyes principle helps in debugging a lot.