The digital marketing and media industries are looking closely at whether blockchain can help solve some serious challenges with transparency, fraud and privacy.

It’s still early days. 2018 will be a year of testing and learning.

"Most interest in blockchain applications for digital advertising centers around bringing transparency to the programmatic ecosystem, which has been blasted in recent years as a murky black box plagued by fraud and shady players," said Nicole Perrin, senior analyst at eMarketer and author of the new report, "Blockchain's Promise: How Digital Advertising May Use It to Increase Transparency, Reduce Friction and Solve Audience Identity Challenges."

Identity management is a key area of interest for marketers, especially as GDPR and privacy concerns make data security and privacy even more important to consumers. And brands have reason to care about transparency in the supply path.

One reason is often referred to as the "ad tech tax"—all the fees incurred as media dollars move from a marketer and its agency through various partners in the programmatic space, including trading desks, demand-side platforms (DSPs), data and targeting vendors, ad verification services, exchanges and so forth, all before reaching a publisher and paying for "working media." The fees unquestionably add up.

According to 2017 data from Warc, programmatic advertisers around the world spent nearly $35 billion on the tech tax last year, equivalent to 55% of programmatic ad spending.

Hear more about blockchain's potential in a new episode of "Behind the Numbers."