Twitter said it has purchased mobile data encryption and security management software firm Whisper Systems.

Twitter purchased the startup for an undisclosed amount to boost mobile security over Google's Android operating system.

"As part of our fast-growing engineering team, they will be bringing their technology and security expertise to Twitter's products and services," the company said in a statement to IT Pro.

Whisper Systems builds security and privacy software applications for managing and encrypting content on mobile devices running the Android OS. The company said it has built a full software stack "all the way from application-level solutions at the top of the stack, down through a hardened version of Android, to kernel modifications at the bottom of the stack".