who is, satoshi nakamoto? have our guesses. >> reporter: every time you use your bitcoin, the transaction is recorded in a public digital, blockchain. >> the blockchain revolutionary approach to security all but unhackable. >> check the ledger. >> it's become a part of college curriculums this class here at new york university. >> we started with 30 students in 2014. now, 235 this term. let's make all the blocks two mga booim mega bytes. >> crypto currency crossed into the mainstream. >> reporter: far cry from the dark past. bitcoin once preferred currency to buy drugs and illicit items on silk road. the fbi eventually shutting down silk road seizing 173,000 bitcoins worth over $1.5 billion today. hi, guys. here with "nightline," ax. back at the crypto castle, we meet a few crypto know mads. >> what got you into it? >> trying to find a way to send money back to china. and western union was charging 12.5% fees for transactions under $1,000 or something. i was making $15 an hour at the time. so, a 12% transact,

policy bitcoins were first programmed ten years ago the developer was known only by a pseudonym satoshi nakamoto to this day the program of behind a technology has never been identified the idea is that everyone who installs the bitcoin software on the desktop or smartphone becomes part of the bitcoin network the digital ledger that supposedly makes bitcoin both independent and secure is what is known as block chain a block chain is a ledger managed by many computers in a network which keep track of records in what are called blocks each block contains information about a transaction the block is checked in very fied by older computers distributed throughout the network and contains security codes from the previous block that practically eliminates the chances of manipulation and count a feat of the current sting. at the moment bitcoin is still on the wild rollercoaster ride in the markets but one thing is fairly certain after all the coins are issued bitcoin won't fall victim to inflation jagow rhythm behind it won't allow the mining of more than twenty one million bitcoins and they'll all have