I recommend the RSA cryptosystem, which has a series of classes in Java specifically for implementing that encryption. A good 1024 bit encryption should be strong enough so long as nobody has a quantum computer. DO NOT attempt to make your encryption from scratch!!! Use tools available to make public / private key pairs.
I recommend the RSA cryptosystem, which has a series of classes in Java specifically for implementing that encryption. A good 1024 bit encryption should be strong enough so long as nobody has a quantum computer. DO NOT attempt to make your encryption from scratch!!! Use tools available to make public / private key pairs.