The G2HEC (Genus 2 HyperElliptic Curve) library is a free portable C++ library providing divisor group operations in the Jacobian of genus 2 (imaginary) hyperelliptic curve. Such curves can be used for discrete-logarithm-based cryptosystems with advantages over elliptic curves (genus 1 curves). Divisor group operations are essential to using genus 2 curves for cryptography.

It is built on top of V. Shoup's NTL library, "a high performance, portable C++ library providing data structures and algorithms for arbitrary length integers; for vectors, matrices, and polynomials over the integers and over finite fields; and for arbitrary precision floating point arithmetic."

It is recommended to build NTL using GMP (the GNU Multi-Precision package) for best performance. However, the G2HEC library can be built and used with and without the existence of GMP.

This library does not assume users' familiarity with any non-trivial math background except basic concepts of finite fields and polynomials. No prior knowledge of genus 2 curve is needed to used the library.

The G2HEC library is released under the GNU General Public License. See the file COPYING for details.

The G2HEC library homepage: http://www.math.purdue.edu/~nshang/g2hec/.

The NTL library homepage: http://www.shoup.net/ntl/.

The GMP library homepage: http://www.swox.com/gmp/.