President Donald Trump signed an executive order in March that boosted the spirits of cryptocurrency investors - and created a digital money mystery.Trump directed the treasury secretary to create two national stockpiles of crypto assets, putting digital currencies alongside gold, foreign currencies and other assets in the U.S. reserve.Subscribe to The Post Most newsletter for the most important and interesting stories from The Washington Post.The assets are to include crypto seized by federal agencies in criminal or civil proceedings. But the government has not disclosed how much bitcoin, or which other crypto coins, it holds.New data on what crypto cash the U.S. government has seized may now provide some answers. It suggests the crypto reserves will together hold more than $21 billion in cryptocurrency.Trump ordered the creation of a Strategic Bitcoin Reserve, which Trump described as "a virtual Fort Knox for digital gold," and a separate U.S. Digital Asset Stockpile to hold other cryptocurrencies. The stockpile will be funded with whatever crypto assets the Treasury holds other than bitcoin, leaving the stockpile's composition to be largely determined by a mixture of chance and criminal conduct.That unconventional method for selecting government financial holdings had the benefit of making the reserves cost-neutral for the taxpayer. It also provided a way to estimate what exactly might go into the two pools before results are released from an official accounting of U.S. crypto holdings that is underway.Because government seizures are disclosed in court documents, news releases and other sources, crypto-tracking firms can use those notices to monitor which digital assets the U.S. government holds.Chainalysis, a blockchain analytics firm, reviewed cryptocurrency wallets that appear to be associated with the U.S. government for The Washington Post. The company estimated how much bitcoin it holds, and the other crypto tokens in its top 20 digital holdings as of May 1