The electronic age has brought forth many technological advances. With these
advances came the need for security and tighter control on how we send
information electronically over the Internet or through a network. Date
encryption is, in its simplest terms, the translation of data into a secret
code. In order to read an encrypted file, the receiver of the file must obtain a
secret key that will enable him to decrypt the file. A deeper look into
cryptography, cryptanalysis, and the Data Encryption Standard (DES) will provide
a better understanding of date encryption. Cryptographic Methods There are two
standard methods of cryptography, asymmetric encryption and symmetric
encryption. Data that is in its original form (unscrambled) is called plaintext.
Once the data is scrambled and in its encrypted form it is called ciphertext.
The ciphertext, which should be unintelligible to anyone not holding the
encryption key, is what is stored in the database or transmitted down the
communication line. Asymmetric encryption (also know as public key encryption)
uses two separate keys, a public key and a private key. The private key is
available only to the individual receiving the encrypted message. The public key
is available to anyone who wishes to send data or communicate to the holder of
the private key. Asymmetric encryption is considered very safe but is
susceptible to private key theft or breaking of the private key (this is
virtually impossible and would constitute trying billions of possible key
combinations) (4). Types of public key algorithms include Riverst-Shamir-Adelman
(RSA), Diffie-Hellman, Digital Signature Standard (DSS), EIGamal, and LUC (5).
Symmetric encryption uses only one key (a secret key) to encrypt and decrypt the
message. No public exchange of the key is required. This method is vulnerable if
the key is stolen or if the ciphertext is broken (4). Types of symmetric
algorithms include DES, Blowfish, International Data Encryption Algorithm
(IDEA), RC4, SAFER, and Enigma (5). Cryptanalysis Cryptanalysis is the art of
breaking cryptography. Methods of cryptanalysis include: „h Ciphertext-only
attack ¡V the attacker works from ciphertext only. The attacker does not know
anything about the message and is merely guessing about the plaintext
(6). „h Know-plaintext attack ¡V the attacker know the plaintext. Knowing
this information, the attacker can attempt to decrypt the ciphertext (6). „h
Chosen plaintext attack ¡V the attacker can have a message encrypted with the
unknown key. The attacker must then determine the key used for encryption (6).
„h Man-in-the-middle attack ¡V the attacker intercepts the key that is being
exchanged between parties (6). Data Encryption Standard (DES) In 1977 the
National Institute of Standards and Technology (NIST) and IBM developed the Data
Encryption Standard, or DES, to provide a means by which data could be
scrambled, sent electronically to a destination, and then unscrambled by the
receiver. DES was developed to protect data in the federal computer systems
against passive and active attacks (3). Every five years the NIST reviews the
DES and determines whether the cryptographic algorithm should be revised, is
acceptable, or completely withdrawn. DES uses a very complex algorithm, or key,
that has been deemed unbreakable by the U.S. government. There are
72,000,000,000,000,000 (72 quadrillion) or more possible encryption keys that
can be used. It applies a 56-bit key to each 64-bit block of data. This process
involves 16 rounds of operations that mix the data and key together using
operations of permutation and substitution. The end result is a completely
scrambled data and key so that every bit of the ciphertext depends on every bit
of the data plus every bit of the key (a 56-bit quantity for DES) (2).
Conclusion Sending secure electronic information is vital for businesses today.
Although the electronic age has made it easier for companies to send and receive
information, it has also increased the need for security. Data encryption in
itself will not assure any business of sending secure information, but
understanding it will surely benefit the company. Businesses who understand
cryptography, cryptanalysis, and Data Encryption Standard are on their way to
understanding data encryption.
1. Bay Networks, Inc. (1997). Configuring Software Encryption.
www.baynetworks.com 2. Biasci, L. (1999). Cryptology. www.whatis.com. 3.
Frazier, R.E., (1999). Data Encryption Techniques. www.softstrategies.com. 4.
Litterio, F., (1999). Cryptology: The Study of Encryption. www.world.std.com. 5.
SSH Communications Security, (1999). Cryptographic Algorithms. www.ipsec.com. 6.
SSH Communications Security, (1999). Introduction to Cryptography.