||PGP (also called "Pretty Good
Privacy") is an encryption method that scrambles
and unscrambles data. It was developed originally by
Phil Zimmermann who is now President of the recently
created corporation PGP, Inc. Phil Zimmermann and other
programmers around the globe have subsequently revised
and improved PGP through numerous versions.
PGP is an Asymmetric cryptosystems (public key cryptosystems)
because it uses one key (the public key) to encrypt
a file (or message or text) and a different key (the
private key) to decrypt it.
PGP uses the RSA public-key encryption system. RSA
was announced in 1977 by its inventors: Ronald Rivest
of MIT, Adi Shamir of the Weizmann Institute in Israel,
and Leonard Adelman of USC. It is called "RSA"
after the initials of these gentlemen. PGP also employs
an encryption system called IDEA.
||The current Advanced Encryption Standard (AES) is
also called Rijndael (pronounced "Rain Doll").
AES is a block cipher designed by Joan Daemen and
Vincent Rijmen. The name Rijndael is composed of two
portions of the last names of the authors (RIJ plus
DAE). The design of Rijndael was strongly influenced
by the design of the block cipher Square. Rijndael
is highly secure and has undergone extensive cryptanalysis.
No weaknesses have been found as of November 2002.
||The Data Encryption Standard (DES) was developed by
an IBM team of engineers in 1973-74 and was adopted
as a national encryption standard in 1977. It has since
been superceded by AES.
||Triple DES is a minor variation of the DES standard.
It takes a 192 bit key (24 characters) as input and
breaks it into three keys. First, DES is used to encrypt
a file using the first key. Then the file is decrypted
using the second key. The final step is to encrypt the
file again using the third key. Note that if all three
64 bit keys are the same, Triple DES is identical to
regular DES. However, if used correctly, this method
of encryption is much more secure than regular DES.
||Blowfish is a symmetric block cipher that can be used
as a drop-in replacement for DES or IDEA. Blowfish was
designed in 1993 by Bruce Schneier. Since then it has
been used considerably and is accepted as a strong encryption
||Serpent was designed by Ross Anderson, Eli Biham and
Lars Knudsen as a candidate for the Advanced Encryption
Serpent was selected as one of the five finalists
in the AES competition that selected Rijndael as the
AES standard. Serpent is faster than DES and uses
a simpler, more secure algorithm.
There are no known attacks that have been successful
in breaking this algorithm.
||MARS is a shared-key (symmetric) block cipher designed
by IBM as a candidate algorithm for the Advanced Encryption
Standard (AES). MARS supports 128-bit blocks and variable
It was selected as one of the five finalists in the
AES competition. MARS is unique in that it combines
virtually every design technique known to cryptographers
in one package. It uses two entirely separate algorithms,
so that even if one portion of MARS is broken the
rest of the cipher will remain secure and data will
still be safe.
Due to its design, MARS offers better security than
triple DES while running significantly faster than
||The Twofish block cipher is Counterpane Labs' candidate
for the new Advanced Encryption Standard. It is one
of the five finalists chosen by NIST from a field of
15 candidates as explained above. Twofish is designed
to be highly secure and highly flexible. It is well
suited for large microprocessors, 8-bit smart card microprocessors,
and dedicated hardware. Counterpane Labs has spent over
one thousand hours cryptanalyzing Twofish, and has found
no attacks that can break the full 16 round version
of the algorithm.