The Mountain View, Calif., security technology vendor VeriSign Inc. has agreed to buy Certicom Corp., a Mississauga, Ontario, cryptography firm.

VeriSign said Friday that it would pay $73 million, or 40% more than an unsolicited takeover bid from Research in Motion Ltd., the maker of BlackBerry devices.

Certicom offers a form of public-key encryption technology called elliptic curve cryptography.

The deal is expected to close in March. Certicom could accept a higher offer but would have to pay VeriSign a $4 million termination fee to do so.