BlackBerry maker RIM has started the hostile takeover bid for security vendor Certicom, as disclosed last week.

RIM said that the subsidiary had filed a circular on the bid and made formal announcements in two Canadian newspapers. Both RIM and Certicom are based in Ontario.

Security is a strong point for the BlackBerry system, in which all email goes through RIM's network operations centre and is encrypted for transit over wireless networks. But BlackBerry devices are not certified for the highest levels of government security, a fact that has been raised recently with the election of BlackBerry user Barack Obama as US president.

The bid of C$1.50 (73p) per share, or about C$66 million (£32 million), represents a premium of about 76.5 percent over the closing price of Certicom shares on 2 December, the day before RIM's public notice that it intended to make the bid.

Certicom, best known for its Elliptic Curve Cryptography technology, provides security software for wireless devices and other products.

RIM started talking with Certicom management in February 2007 about a possible acquisition, it said last week. RIM said it hadn't been able to engage Certicom in a "meaningful dialogue" but still believed the company was a perfect fit for RIM and would benefit shareholders, employees and customers. As a result, RIM made its offer directly to Certicom shareholders.

The buyout would be financed with cash on hand, with no need for financing conditions, according to RIM.

The offer is open until 15 January or until withdrawn, RIM said.