This class defines the Service Provider Interface (SPI)
for the KeyPairGenerator
class, which is used to generate
pairs of public and private keys.
All the abstract methods in this class must be implemented by each
cryptographic service provider who wishes to supply the implementation
of a key pair generator for a particular algorithm.
In case the client does not explicitly initialize the KeyPairGenerator
(via a call to an initialize
method), each provider must
supply (and document) a default initialization.
For example, the Sun provider uses a default modulus size (keysize)
of 1024 bits.