Usign provides public key signatures using the ed25519 algorithm.

The home page for the algorithm is http://ed25519.cr.yp.to/.
It is described in the following paper:

Daniel J. Bernstein, Niels Duif, Tanja Lange, Peter Schwabe, Bo-Yin Yang
High-speed high-security signatures
Journal of Cryptographic Engineering 2 (2012), 77–89
2011-09-26
http://ed25519.cr.yp.to/ed25519-20110926.pdf

To build and install the package run

mkdir build
cd build
cmake ..
make
sudo make install