PBC Library Manual 0.5.11 - Stanford Crypto Group

Chapter 1. Installing PBC
The first line generates a random element g of the group G1, while the second prints out the value of g.
(The syntax was influenced by bc, an arbitrary precision calculator.) Next, enter:
h := rnd(G2);
h;
This assigns h to a random element of the group G2. Actually, the default pairing pbc uses is symmetric
so G1 and G2 are in fact the same group, but in general they are distinct. To compute the pairing applied
to g and h, type:
pairing(g,h);
The order of both g and h is r. Let’s generate two random numbers between 1 and r:
a := rnd(Zr);
b := rnd(Zr);
1.4. Basics
By bilinearity, the resulting output of both of these lines should be identical:
pairing(g^a,h^b);
pairing(g,h)^(a*b);
This program has other features but the commands shown here should be enough to quickly and
interactively experiment with many pairing-based cryptosystems using real numbers.
Programs using the PBC library should include the file pbc.h:
#include
and linked against the PBC library and the GMP library, e.g.
$ gcc program.c -L. -lpbc -lgmp
The file pbc.h already includes gmp.h.
PBC follows GMP in several respects:
• Output arguments generally precede input arguments.
• The same variable can be used as input and output in one call.
• Before a variable may be used it must be initialized exactly once. When no longer needed it must be
cleared. For efficiency, unnecessary initializating and clearing should be avoided.
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