Java IO.pdf - Nguyen Dang Binh

IDEA
RC2
RC4
Blowfish
Java I/O
The International Data Encryption Algorithm developed and patented by Dr. X. Lai and
Professor J. Massey of the Federal Institute of Technology in Zurich, Switzerland; a symmetrical
64-bit block cipher with a 128-bit key; the algorithm is published but patented. The patent
expires in 2010 in the U.S., 2011 in Europe; see http://www.ascom.com/infosec/idea.html.
A variable key-size symmetric 64-bit block cipher designed by Ron Rivest as a drop-in
replacement for DES; it is generally allowed to be exported with a 40-bit key size and sometimes
with a 56-bit key length (which probably means the NSA doesn't have much trouble breaking it);
see IETF RFC 2268, http://www.faqs.org/rfcs/.
A symmetric stream cipher algorithm proprietary to RSA Data Security, Inc. used in Netscape's
Secure Sockets Layer (SSL), among other products. RC4 is a stream cipher designed by Ron
Rivest; since the U.S. government occasionally allows this to be exported, the NSA probably
knows how to break it. See ftp://idea.sec.dsi.unimi.it/pub/security/crypt/code/rc4.revealed.gz and
Chapter 17.1 of Bruce Schneier's Applied Cryptography.
An unpatented fast, free, symmetric, variable key length (32 to 448 bits) 64-bit block cipher
designed by Bruce Schneier as a drop-in replacement for DES; see
http://www.counterpane.com/blowfish.html.
When faced with input longer than its block size, a block cipher must divide and possibly
reorder that input into blocks of the appropriate size. The algorithm used to do this is called a
mode. A mode name may be included in the transformation string separated from the
algorithm by a slash. If a mode is not selected, the provider supplies a default. Modes apply to
block ciphers in general and DES in particular, though other block ciphers like Blowfish may
use some of these modes as well. The named modes in the JCE are listed in Table 10.4. All of
these modes are supported by the JCE, but modes are algorithm-specific. If you try to use an
unsupported mode or a mode that doesn't match the algorithm, a
NoSuchAlgorithmException is thrown.
Table 10.4. Block Cipher Modes
Name Mode
Electronic CodeBook Mode; the 64-bit blocks are encrypted independently of each other and may also be
decrypted independently of each other, so this mode is useful when you want random access to an
encrypted file but in general is less secure than other modes. It does not require an initialization vector.
ECB
See "DES Modes of Operation," National Institute of Standards and Technology Federal Information
Processing Standards Publication 81, December 1980; see http://www.itl.nist.gov/div897/pubs/fip81.htm
(NIST FIPS PUB 81).
Cipher Block Chaining Mode, as defined in NIST FIPS PUB 81; best choice for encrypting files; uses an
CBC
initialization vector.
K-bit Cipher FeedBack Mode, as defined in NIST FIPS PUB 81; best choice for real-time encryption of
CFB streaming data such as network connections where each byte must be sent immediately rather than being
buffered; uses an initialization vector.
K-bit Output FeedBack Mode, as defined in NIST FIPS PUB 8; designed so that a 1-bit error in the
OFB ciphertext only produces a 1-bit error in the plaintext; therefore, the best choice on noisy, error-prone
channels; uses an initialization vector.
Propagating Cipher Block Chaining, as used in pre-Version 5 Kerberos; similar to the more secure CBC
PCBC
mode used in Kerberos Version 5 and later; uses an initialization vector.
If the algorithm is a block cipher like DES, then the transformation string may include a
padding scheme that's used to add extra bytes to the input to fill out the last block. The named
padding schemes are shown in Table 10.5. Algorithms that use modes must generally also
specify the padding scheme.
215