Cryptography yields an asymmetric advantage to those who use it. Asymmetric how? In a fraction of a second, your laptop can form a secure (read: encrypted) connection with your bank. But if an eavesdropper intercepted the communications, it could take - literally - billions of years before they decrypt the data.
Libertarians love cryptography. Why? For the same reason they love guns: cryptography decentralizes power. Compared to the physical world, where goverments & mobs enjoy near-total control, the digital realm is a bastion of Individualism. Peers converse, unauthorized; information is traded, unhindered; activists gather, unharrassed.
Decentralization is powerful. The American defeat in Vietnam serves as an example. So does Bitcoin, BitTorrent, and the internet itself. Shutting down a decentralized system is like playing Whack-A-Mole: you only win if you unplug the machine. What government can afford to revert to a pre-digital economy?