This Bluelock icon is made in Material Design style developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 4,300 icons, all in the same style and quality.
It is a shape like a tilted rectangle with rounded corners, but the upper left and lower right areas extend beyond the corners of the rectangle, and it is tilted so that the upper right corner is at the top. Inside this shape is another tilted rectangle, this one with sharp corners.