Although it is widely believed that Satoshi was an inflation-hating goldbug he never said this, and in fact programmed Bitcoin's money supply to grow indefinitely, forever. He modeled the monetary supply as 4 gold mines being discovered per mibillenium (1024 years), with equal intervals between them, each one being depleted over the course of 140 years.

This poses obvious problems, however. Prominent among them is the discussion on what to call 1 billion Bitcoin, which symbol color to use for it, and when wallet clients should switch to it by default.

To combat this, this document proposes a controversial change: making Bitcoin's monetary supply finite.

Details

As is well known, Satoshi was a master programmer whose knowledge of C++ was surpassed only by his knowledge of Japanese culture. The code below:

    int64_t nSubsidy = 50 * COIN;
    // Subsidy is cut in half every 210,000 blocks
    // which will occur approximately every 4 years.
    nSubsidy >>= (nHeight / 210000);
is carefully written to rely on undefined behaviour in the C++ specification - perhaps so it can be hardware accelerated in future.

The block number is divided by 210000 (the "apparent" subsidy halving interval in blocks), and the result is used as input for a binary shift, applied to the original payout (50 BTC), expressed in base units. Thanks to the new-goldmine interval being exactly 64 times the halving interval, and 64 being the size in bits of the currency datatype, the cycle repeats itself every 64 halvings on all currently supported platforms.

Despite the nice showoff of underhanded programming skills - we want Bitcoin to be well-specified. Otherwise, we're clearly in for a bumpy ride