17 Dec
2003
17 Dec
'03
11:17 p.m.
AFAIK, RSA is the only feasible PK scheme available. There's eliptic curves, of course, but that's patented. There are plenty of others, like Rabin's scheme, that are quite practical, but just not used because they are all collectively patented. After that patent expires in '97 things may change.
There are different uses for public-key systems, and some systems support some but not all of the uses. For instance, Diffie-Hellman is useful for key exchage (and patented till 1997), and the NIST/NSA's DSS Digital Signature Standard is useful for signatures, especially if you like subliminal channels in your signatures :-), though the patent status depends on whether you believe NIST or RSA ....