Potential Downfalls Privacy issues aren't the only hurdle. Private keys, for instance, need to be protected in order to work. If stored on a computer's hard drive, it's not that difficult for an unauthorized party to gain access to a key. In the long run, this will make obvious the needs for other types of authentication down to a personal level. Such authentication would likely include biometric identifiers like fingerprints or retina scans, which require additional infrastructure to implement.
Portability is another issue.
In the world of physical signatures, pens are very portable. Another issue of concern involves the interoperability of multiple key technologies and the question of how electronic signatures will integrate with digital signatures. The language of the e-sign bill reflects a concern that government policies could bog down the development of the technology. Therefore the issue of standards was left open. The U.S. Department of Commerce, however, is charged with coming back within 180 days to give recommendations on how the harmonization of electronic signature technology might be achieved on a global basis.