It is poor policy to clamp down indiscriminately on a technology just because some criminals might be able to use it to their advantage. For example, any U.S. citizen can freely buy a pair of gloves, even though a burglar might use them to ransack a house without leaving fingerprints. Cryptography is a data-protection technology, just as gloves are a hand-protection technology. Cryptography protects data from hackers, corporate spies, and con artists, whereas gloves protect hands from cuts, scrape, heat, cold, and infection. The former can frustrate FBI wire-tapping, and the latter can thwart FBI fingerprint analysis. Cryptography and gloves are both dirt-cheap and widely available. In fact, you can download good cryptographic software from the Internet for less than the price of a good pair of gloves.

Response to tim_three: I don't think Mr. Rivest, here, is talking about free as in beer, but free as in legal. Whether software patents/algorithm patents are good is a seperate topic from whether it is legal to create/sell/use/export cryptographic software. Anyway it is kind of moot now since the patent has expired.