It is a secure method, in that fonts can only be used for the pages they were intended for, and not on other sites, or in other applications.
A WebFont Player plugin was available for Internet Explorer, but the technology had to compete against Microsoft's Embedded Open Type fonts natively supported by Internet Explorer 4 and up (Windows versions only).
Another impediment was the lack of open-source or free tool to create webfonts in TrueDoc format, whereas Microsoft made available a free Web Embedding Fonts Tool to create webfonts in their format.
Corel Draw X4 was one of the few graphic design programs with the option of using the TrueDoc system while saving files.
Monotype Imaging, which acquired Bitstream's font business, neither markets the TrueDoc technology nor offers it for sale.