An industry group backed by Microsoft, Intel, and Texas Instruments announced "a new protocol to mitigate risks from maliciously embedded hardware or software in USB devices attempting to exploit a USB connection."
The USB Promoter Group 3.0 defined the authentication protocol of USB-Type-C, so companies and users can be assured that "certified" USB products are safe to use.
"For a traveler concerned about charging their phone at a public terminal, their phone can implement a policy only allowing charge from certified USB chargers. A company, tasked with protecting corporate assets, can set a policy in its PCs granting access only to verified USB storage devices."
Read the complete USB-Type-C authentication announcement for yourself for more details.