Edgar Allan Poe may have thought that "human ingenuity cannot concoct a cipher which human ingenuity cannot resolve" but recently the wide availability of significant computing power has shifted the balance in the struggle for secrecy from governments in favour of individuals.
At the same time, e-commerce demands products that allow secure Internet transactions and is turning to cryptography to provide them.
National security and law enforcement interests motivate governments to try to control individual use of encryption, sometimes by direct restrictions on the technology itself and more often by controlling its export. While national rules are increasingly being harmonised (in particular to implement the Wassenaar Arrangement), differences remain.
