For anyone who has watched the last few years of cat-and-mouse games on the dark web's black markets, the pattern is familiar: A contraband bazaar like the Silk Road attracts thousands of drug dealers and their customers, along with intense scrutiny from police and three-letter agencies. Authorities hunt down its administrators, and tear the site offline in a dramatic takedown—only to find that its buyers and sellers have simply migrated to the next dark-web market on their list.

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