encryption algorithm


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encryption algorithm

A formula used to turn ordinary data, or "plaintext," into a secret coded message known as "ciphertext." The ciphertext can reside in storage or travel over unsecure networks without its contents being divulged to unauthorized people.

Also known as a "cipher," each algorithm uses a randomly generated string of bits known as a "key" to perform the calculations. The larger the key (the more bits), the greater the number of potential patterns can be created, thus making it harder to break the code and decrypt the contents.

Most encryption algorithms use the block cipher method, which codes fixed blocks of input. Others use the stream method, which encrypts one bit at a time. See mode of operation, cryptography, security protocol, stream cipher, block cipher and algorithm.


Algorithm Choices
Excerpted from a ScramDisk dialog, which was an application that encrypted files on the hard drive, this shows a selection of algorithms. "Mouse entropy" is the amount of randomness introduced into the creation of the key. The more the mouse is jiggled, the more randomness. Following are excerpts from the program's documentation, which provide a brief summary of secret key algorithms.







3DES
This is far better than DES; it uses three applications of the DES cipher in EDE (Encipher-Decipher-Encipher) mode with totally independent keys. Outer-CBC is used. This algorithm is thought to be very secure (major banks use it to protect valuable transactions), but it is also very, very slow.

Blowfish
Blowfish is a high security encryption alogorithm designed by Bruce Schneier, the author of Applied Cryptography and owner of the company Counterpane. It is very fast, is considered secure and is resistant to linear and differential analysis. This is my personal cipher of choice.

DES
Data Encryption Standard was designed in the early 1970s by IBM with input from NSA. It is OK, but a single key can be broken in three days by the Electronic Frontier Foundation, a poorly funded organization. This algorithm was provided for completeness.

IDEA
International Data Encryption Algorithm was produced by Xuejia Lai and James Massey. It is fairly fast, is considered secure, and it is also resistant to both linear and differential analysis. To use this for anything other than personal use, a royalty must be paid to Ascom-Systec Ltd.

Misty1
Misty1 was designed by M. Matsui of Mitsubishi. It is a reasonably fast cipher that is resistant to both linear and differential analysis. It is fairly new though, so use it with caution.

Square
Square is a very fast and reasonably secure block cipher produced by John Daemen and Vincent Rijmen. It hasn't been subject to as much peer review as Blowfish, 3DES, IDEA, etc., so it may be susceptible to attacks.

Summer
This is a proprietary stream cipher constructed by the author and is designed for speed alone. It is supplied for backward compatibility with Version 1 of ScramDisk and is not recommended for use on newly created disks. Instead, use TEA or Blowfish, which are both reasonably fast.

TEA
Tiny Encryption Algorithm is a very fast and moderately secure cipher produced by David Wheeler and Roger Needham of Cambridge Computer Laboratory. There is a known weakness in the key schedule, so it is not recommended if utmost security is required. TEA is provided in 16 and 32 round versions. The more rounds (iterations), the more secure, but slower.

                        Block  KeyEncryption               Size  SizeType      Author         Bits  Bits  Time**

 3DES      Diffie-Hellman   64   168  4:05

 Blowfish  Schneier         64   256  0:55

 DES       IBM-NSA          64    56  1:42

 IDEA      Lai-Massey       64   128  1:07

 Misty1    Matsui           64   128  2:50

 Square    Daemon-Rijmen   128   128  0:39

 Summer    Aman       (stream)   128  0:46

 TEA 16    Wheeler-Needham  64   128  0:46

 TEA 32    Wheeler-Needham  64   128  1:03

 **Minutes/seconds to encrypt a 50MB file.
   Although times are based on an older
   166 MHz Pentium, the list serves as an
   algorithm speed comparison.
References in periodicals archive ?
Zhang, "Multiple lookup table-based aes encryption algorithm implementation," Physics Procedia, vol.
To enhance the security of the encryption algorithm by combining with the principle of visual cryptography, the image is divided into two subimages, and the pixel value is further scrambled to achieve pixel diffusion.
An effective encryption algorithm must have a very good resistance to noise interference, so that when decrypting, the distortion of the image is as low as possible, and the impact is as little as possible.
To evaluate our image encryption algorithm, we conduct extensive experimental analysis on several standard images with varied sizes.
The sender uses some encryption algorithms and shared key to converting plain text into cipher text whereas, the receiver converts the ciphered text into plain text using the decryption algorithm with the key shared by the sender.
The evaluation of the existing encryption algorithms allows us to extract the black dots that affect their performance and their security.
We know that a permutationonly scheme is insecure for any image encryption algorithm owing to the invariance of the statistical property; it only shuffles the pixel positions.
It is obvious that the entropies of the cipher images are very close to the theoretical value of 8, which means that the encryption algorithm has ability of resisting statistical attack.
[10] used DNA as an information carrier and realized a onetime traditional encryption algorithm using biochemical technology in a DNA molecule.
proposed an image encryption algorithm using 2D Sine Logistic modulation map that has better properties of chaos when compared with some existing chaotic systems [15].