BXA since export control jurisdiction was transferred from the State Department to the Commerce Department in 1996. At the time this guide was published, the most recent update was in October 2000.
Electronic Frontier Foundation's Crypto Export archive (contains political articles, discussions, and notes).
Information Security and Privacy in Network Environments (lengthy Sept. 1994 political report; use your browser's Search or Find function with the text "Government Policies and Cryptographic Safeguards" to find the relevant chapter).
RSA Laboratories' FAQ about Today's Cryptography: United States Cryptography Export/Import Laws (particular note of interest: reports on the legality of RSA and Triple-DES export).
U.S. Department of Commerce / The Bureau of Export Administration / Office of Strategic Trade and Foreign Policy Controls / Information Technology Controls Division / Commercial Encryption Export Controls.
Defined below are some of the terms used throughout this guide. For a more comprehensive look at cryptography terms, try some of the following sites:
Follow the link from the term to read more about it (often on another site).
A Block Cipher is a method for encrypting data in chunks (several or many contiguous bits) as opposed to encoding bit-by-bit like a stream cipher. (More information.)
A Stream Cipher is a method of encrypting data bit-by-bit, as opposed to encoding a contiguous chunk of data all at once like a block cipher. (More information.)
Acronyms and terms that you have encountered in this guide that are not listed here may be encryption standards or algorithms. For more information please see Appendix B: What are the different kinds of algorithms that encryption software programs utilize?
As discussed in section 5, "What are the vulnerabilities in encryption and how do I guard against them?," "brute force" cracking is a method of finding a password or key by trial and error. The longer the password or key, the more difficult it becomes to crack it. For example, a 56-bit key has 256 possible keys. That's up to 72,057,594,037,927,936 seventy-two quadrillion keys that must potentially be tried in order to find the correct one.
That doesn't mean that a 56-bit key is strong enough to prevent successful brute force attacks. Even back in 1997 when desktop computers were much less powerful than current models (this guide was written in September 2001), a distributed computing effort cracked the RSA's 56-bit RC5 encryption in less than 250 days. (See an article on the effort. A distributed computing effort is one in which many computers share the task of testing the seventy-two quadrillion possible combinations of bits.) In 1998, a similar effort took just 39 days using 50,000 computers. Those computers tried 85% of the possible combinations, at speeds that at times reached 26 trillion keys per second, before finding the right key. Another 1998 effort, by the Electronic Frontier Foundation, took only 3 days to crack a 56-bit DES key using a special computer called the DES (Data Encryption Standard) Cracker.
In some cases, viruses have invaded computers and used their computing power without the owner's knowledge. (GRC.com has a story about a malicious cracker who launched a denial-of-service attack that flooded a computer with more data than it could process, using 474 Microsoft Windows computers without their owners' knowledge.)
Fortunately, increasing the number of bits in a key exponentially increases the number of possible keys that would have to be tested with the "brute force" method. So, a 128-bit key could be any one of 3.4 * 1038 keys, a 192-bit key could be any one of 6.2 * 1057 keys, and a 256-bit key could be any one of 1.1 * 1077 keys. A note at the U.S. Computer Security Resource Center's Advanced Encryption Standard FAQ states:
In the late 1990s, specialized "DES Cracker" machines were built that could recover a DES key after a few hours. In other words, by trying possible key values, the hardware could determine which key was used to encrypt a message. Assuming that one could build a machin