Around the time he immigrated to Chicago from Ukraine as a teenager in 1991, Max Levchin became obsessed with cryptography. Living under the old Soviet regime convinced him of the need to carry out communications undetectable by authorities. As a computer science student at the University of Illinois, he immersed himself in the mathematics of creating and breaking codes, not only making it the focus of his studies but also, he says, turning his pursuit into a "huge hobby" that consumed countless days and nights at the supercomputer center on the Urbana-Champaign campus. Dreaming that he would one day profit from his passion, Levchin aimed to start a company that would process financial transactions over the Internet, devising codes so secure that hackers wouldn't be able to read the data even if they intercepted them. He moved to Silicon Valley after graduation in 1998 to make good on his goal.

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