A Master Lock product Tobias tested uses Kensington's key-lock mechanism, he said.
Tobias released information recently about two other devices he recently tested, a Kensington three-thumbwheel combination lock and a Compucage product consisting of a cagelike enclosure for bolting a laptop to a desk surface.
He said the Kensington combination lock can be compromised using tactile pressure and visual observation. Defeating the Compucage enclosures is more straightforward: All a thief needs is a shim to open a locking bar, Tobias said.
Canada-based Compucage said it was looking into Tobias' findings.
Tobias has tested other laptop locks. He says a PC Guardian combination lock appears to be well-designed. "It's a nice piece of work."
Some laptop users said Tobias' findings confirm what they already suspected: Laptop cable locks alone don't represent ironclad security.
Andy Lax, a San Francisco public-relations consultant, said he'll probably keep using such cable locks as a "casual deterrent" but places more stock in the sturdy locks on his office door and cabinets.
"I'm a bit disappointed" with the cable-lock makers, said Lax, who uses the Targus combination lock, after learning of the Security.Org warnings. But, he added, what do you expect for $35?