Chicago private equity firm Thoma Bravo is buying a majority stake in encryption software maker DigiCert from TA Associates for undisclosed terms.  TA Associates will retain a minority stake in DigiCert, which it acquired in 2012. Lehi, Utah-based DigiCert, founded in 2003, makes authentication and encryption software for government agencies, financial institutions and technology companies, serving more than 115,000 customers across 180 counties. Some of DigiCert’s customers include Facebook Inc. (Nasdaq: FB), PayPal Holdings Inc. (Nasdaq: PYPL), Yahoo! Inc. (Nasdaq: YHOO) and International Business Machines Corp. (NYSE: IBM). Encryption has become an important line of defense in the battle against hackers for companies and government agencies alike. Recent high-profile hacking events have compromised a wide range of websites, including the U.S. Office of Personnel Management , the University of Virginia and the Ashley Madison extramarital dating site. “We look forward to adding Thoma Bravo’s strategic insight and influence as we embark on our next phase of growth,” says DigiCert CEO Nicholas Hales. The investment follows Thoma Bravo’s purchase of life insurance software provider iPipeline earlier in 2015. Thoma Bravo won Mergers and Acquisitions’ M&A Mid-Market award for Deal of the Year with the $930 million purchase of TravelClick, which was completed in May 2014. Kirkland & Ellis and Jefferies LLC are advising Thoma Bravo. Evercore Partners Inc. (NYSE: EVR) and Goodwin Procter are DigiCert’s financial advisers. Thoma Bravo is receiving financing from Jefferies Finance LLC and Fifith Street Finance Corp. (Nasdaq: FSC).