During the time that the RSA patent was in force, DSA was the signature algorithm of choice for any software that didn't want to deal with patent licenses. (Which is why lots of old PGP keys are still DSA.) It has slowly disappeared since the patent expired and it appears that 4096-bit RSA is now the algorithm of choice if you're on the run from the NSA [1]. (And if you're a journalist trying to get a reply: keyid BDA0DF3C.)
But DSA can also be used with elliptic curves in the form of ECDSA and, in that form, it's likely that we'll see it return in the future, at least to some extent. SSH and GPG both support ECDSA now and CAs are starting to offer ECDSA certificates for HTTPS.
Unfortunately, DSA has an important weakness that RSA doesn't: an entropy failure leaks your private key.
read more..........http://www.imperialviolet.org/2013/06/15/suddendeathentropy.html
But DSA can also be used with elliptic curves in the form of ECDSA and, in that form, it's likely that we'll see it return in the future, at least to some extent. SSH and GPG both support ECDSA now and CAs are starting to offer ECDSA certificates for HTTPS.
Unfortunately, DSA has an important weakness that RSA doesn't: an entropy failure leaks your private key.
read more..........http://www.imperialviolet.org/2013/06/15/suddendeathentropy.html