Whisper, a mobile app (and service) that allows people to anonymously share their secrets, has raised a large round of funding (rumored to be about $15 million) from top investors according to Silicon Valley sources. We are told that company is being valued at $100 million and Sequoia Capital is leading the series B round of financing. The app allows you to share secrets by putting them on top of photos and illustrations, very much like PostSecret, another popular (if somewhat older) service. It launched in May 2012, and is steadily growing in popularity.

Roelof BoethaRoelof Botha, (partner at Sequoia Capital), fresh off the successful sale of Tumblr to Yahoo is said to be leading this round of financing. I have reached out to Boetha for comment.  The company, co-founded by Michael Heyward and Brad Brooks raised $3 million in Series A funding from LightSpeed Venture Partners, Trinity Ventures and Shoedazzle founder Brian Lee. Heyward declined to comment.

Whisper is an offshoot from a messaging startup, TigerText and is part of the growing number of mobile and web applications that are based on the notion of anonymity. Private social networks such as Snapchat are getting attention (and thus high valuations from investors) in the market at a time when large social networks such as Facebook (S FB) in an effort to find growth are making social content more public. My colleague Mathew Ingram recently noted that as the mobile web evolves, we are constantly seeking impermanence offered by services such as Snapchat and Whisper.