The

usdsi.com

website is no longer available.
The website of US Data Security Inc. operated from 1998 to 2009. The company was active in the field of Public Key Cryptography and established the "US Data Security Public-Key Challenge", a contest on a new method of Public key encryption called the TTM (Tame Transformation Method).

For further information about Public Key Cryptography, please visit the Wikipedia article here.