Chip designer Rambus has agreed to buy privately-held Cryptography Research, a security technology company, in a deal worth $342.5 million, adding to its portfolio of technology available for licensing.

Cryptography Research, or CRI, owns and licenses security technology for network security, financial services and content protection, Rambus said in a statement.

Los Altos, California-based Rambus, which designs and licenses high-speed memory chips, said it will pay $167.5 million in cash, along with 6.4 million of its shares and a $50 million payment to privately-held CRI's employees over three years.

Shares of Rambus declined 2 percent in extended trade after

after closing up 2.07 percent at $19.27.

(Reporting by Noel Randewich; editing by Carol Bishporic)