INTRODUCTION: Blowfish, a symmetric block cipher developed by Bruce Schneier[SCHN93, SCHN94), is a Feistel network, iterating simple encryption and decryption functions of 16 times each. The block size is 64 bits, and the key can be any length up to 448 bits. Although there is a complex initialization phase required before any encryption can take place, the actual encryption of data is very efficient on large microprocessors. Blowfish was designed to have the following characteristics: Fast: Blowfish encrypts data on 32-bit microprocessors at a rate of 18 clock cycles per byte. Compact: Blowfish can run in less than 5K of memory. Simple: Blowfish's simple structure is easy to implement and eases the task of determining the strength of the algorithm. Variably secure: The key length is variable and can be as long as 448 bits. This allows a tradeoff between higher speed and higher security. Blowfish encrypts 64-bit blocks of plaintext into 64-bit blocks of ciphertext. Blowfish is implemented in numerous products and has received a fair amount of scrutiny. So far, the security of Blowfish is unchallenged. DESIGN DECISIONS Based on Schneier's design parameters, he have made these design decisions. The algorithm should: - Manipulate data in large blocks, preferably 32 bits in size (and not in single bits, such as DES). - Have either a 64-bit or a 128-bit block size. - Have a scalable key, from 32 bits to at least 256 bits. - Use simple operations that are efficient on microprocessors: e.g., exclusiveor, addition, table lookup, modular- multiplication. It should not use variablelength shifts or bit-wise permutations, or conditional jumps. - Be implementable on an 8-bit processor with a minimum of 24 bytes of RAM (in addition to the RAM required to store the key) and 1 kilobyte of ROM. - Employ precomputable subkeys. On large-memory systems, these subkeys can be precomputed for faster operation. Not precomputing the subkeys will result in...

...Image Encryption Using Block-Based Transformation Algorithm
Abstract:Encryption is mainly used to transmit the data over networks. There are so many techniques introduced which are used to protect the confidential image data from any unauthorized access. Multimedia data contains different types of data that includes text, audio, video, graphic,images with the increasing use of multimedia data over internet, here comes a demand of secure multimedia data. Most of the encryption algorithm available is generally used for text data and not suitable for multimedia data. In this paper we discuss a block based transformation algorithm in which image is divided in to number of blocks. These blocks are transformed before going through an encryption process. At the receiver side these blocks are retransformed in to their original position and performed a decryption process which gives the original image. Advantage of this approach, is that it reproduce the original image with no loss of information for the encryption and decryption process we used a blowfish algorithm.
KEYWORDS:Image Encryption, Image Correlation, Decryption, Image Entropy, Permutation.
INTRODUCTION
Encryption is a common technique to uphold image security in storage and transmission of digital images are exchanged over network types. The information security has become more important with...

...A
TERM
PAPER
ON
“BlowfishEncryption Algorithm“BLOWFISHENCRYPTION ALGORITHM”
WRITTEN BY
NDIFON, PATRICK MANYOR
10/50050
COMPUTER SCIENCE
UNIVERSITY OF CALABAR
SUBMITTED TO
DR. F.U. OGBAN
COURSE LECTURER
IN PARTIAL FUFILMENT OF THE COURSE REQUIREMENT
CSC4211
SEPTEMBER 2014
TABLE OF
CContentsONTENTS
1. Introduction
2. Origin/Founder
3. Algorithm/Data Structures
4. Category/Performance:
5. Pseudocode
6. Implementation: C++, Java
7. Compare: Associated algorithm
8. Summarize
9. Conclusion
10. References
BLOWFISHENCRYPTION ALGORITHM
General
Designers
Bruce Schneier
First published
1993
Successors
Twofish
Cipher detail
Key sizes
32–448 bits
Block sizes
64 bits
Structure
Feistel network
Rounds
16
Best public cryptanalysis
Four rounds of Blowfish are susceptible to a second-order differential attack (Rijmen, 1997);[1] for a class of weak keys, 14 rounds of Blowfish can be distinguished from a pseudorandom permutation (Vaudenay, 1996).
1. INTRODUCTION
The need for information security has resulted in many Encryption algorithms being developed. This term paper is aimed at analyzing one of those algorithms; the ‘BlowfishEncryption Algorithm’. What is an algorithm? One might ask. What is encryption? Before we can fully understand the ‘BlowfishEncryption...

...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 data encryption.
Cryptographic Methods There are two standard methods of cryptography, asymmetricencryption 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 cipher text. The cipher text, 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...

...TDES, AES, Blowfish and
Two fish Encryption Algorithm: Based on
Space Complexity
MD Asif Mushtaque
Harsh Dhiman
M.Tech(CS&E)
School of Computing Science and Engineering
Galgotias University, Greater Noida, U.P .
M.Tech(CS&E)
School of Computing Science and Engineering
Galgotias University, Greater Noida, U.P.
Shahnawaz Hussain
Shivangi Maheshwari
M.Tech(CS&E)
School of Computing Science and Engineering
Galgotias University, Greater Noida, U.P.
M.Tech(CS&E)
School of Computing Science and Engineering
Galgotias University, Greater Noida, U.P.
(ii)
IJE
RT
Abstract--Due to fast growing of telecommunication
technology and limitation for information transmission there is
a need to use an efficient cryptography algorithm which takes
less space after encryption for the ciphertext. Some
performance matrics (such as time, speed and throughput)
make the algorithm better. In this paper, we analyze and find
an efficient encryption algorithm which takes less space among
these encryption algorithms such as DES, TDES, AES,
Blowfish and Twofish.
Keywords— Space complexity, Encryption, Decryption,
Symmetric Key, Private Key, DES, TDES, AES, Blwofish,
Twofish.
I.
INTRODUCTION
Cryptography is a technique or method to secure our
personal data from unauthorized user. In cryptography two
types of operation are performed. (i)...

...According to searchsecurity.techtarget.com, “Encryption is the conversion of data into a form, called a ciphertext that cannot be easily understood by unauthorized people.” In order to understand the data or the message that is being sent, the receiver must be able to decrypt the message. Decryption thus refers to the process of converting the message from cipher text into its original format or plaintext whereby the reader would be able to understand the message.Encryption is used to ensure the confidentiality of a message that is being sent is not compromised as in case of the message being intercepted, it ensure that only authorized individuals are able to understand the contents. As technology has been advancing, the complex nature of encrypting and decrypting messages have also been advancing. Individuals and experts now create even harder to crack algorithms and formulae for encrypting data. Despite this, there are quite often ways in which a captured message can be decrypted without the use of brute force.
The attack would be one that is based on cipher text only (www.londoninternational.ac.uk). This means that only the cipher text is acquired but has no knowledge of the meaning of the message in plaintext. One can try to critically and statistically analyze the cipher text, in order to try and derive the meaning of the encrypted text or look for combinations of common letters or character strings that would aid in the decrypting and...

...Data Encryption Standard
In 1972, the NBS Institute for Computer Sciences and Technology (ICST) initiated a project in computer security, a subject then in its infancy. One of the first goals of the project was to develop a cryptographic algorithm standard that could be used to protect sensitive and valuable data during transmission and in storage. Prior to this NBS initiative, encryption had been largely the concern of military and intelligence organizations. The encryption algorithms, i.e., the formulas or rules used to encipher information, that were being used by national military organizations were closely held secrets. There was little commercial or academic expertise in encryption. One of the criteria for an acceptable encryption algorithm standard was that the security provided by the algorithm must depend only on the secrecy of the key, since all the technical specifications of the algorithm itself would be made public. NBS was the first to embark on developing a standard encryption algorithm that could satisfy a broad range of commercial and unclassified government requirements in information security. Ruth M. Davis, then Director of ICST, asked the National Security Agency (NSA) to help evaluate the security of any cryptographic algorithm that would be proposed as a Federal standard. She then initiated the standard’s development project by publishing an invitation in the Federal...

...discussed
further: What sorts of cryptanalytic adversaries should be considered in the
world of lightweight cryptography? Does it make sense to allow access to the
complete set of matched inputs and outputs for an algorithm with a 128-bit block
size? One might argue that the amount of data encrypted by a single lightweight
device during its functional lifetime will be tiny, and data to which an adversary
has access will likely remain small when this tiny quantity is summed over all
devices using a common key. In addition, for devices that can’t be secured
physically, practical (side-channel, reverse engineering) attacks will likely take
precedence over cryptanalytic ones. The point is that there is a price to be
paid (with every encryption) for blocking purely theoretical weaknesses, and it
makes sense to think about what price is justiﬁed.
Since there is not yet a fully crystallized point of view on this issue, we have
proceeded in a more-or-less standard fashion. S and S have been
designed to provide security against traditional adversaries who can adaptively
encrypt and decrypt large amounts of data. We concede that (as is the case
with other algorithms) there will be what amount to highly optimized ways to
exhaust the key that reduce the cost of a naive exhaust by a small factor. We
have also made a reasonable eﬀort to provide security against adversaries who
can ﬂip key bits, and our aim is that there should be no related-key...

...Engineering Department
Cryptography & Network Security
CPE (541)
HW#5
Contemporary Symmetric Ciphers
(Double-DES, Triple-DES & Blowfish)
Supervised by:
Dr Loái Tawalbeh
Eng. Sulaiman Al-Basheer
Simsam R.Hijjawi
20022171043
Review Problems:
6.1 What is the triple encryption?
It is a three-stages encryption with three different keys, to avoid costly requirements arises from using three different keys with total length of 3x56 = 186 bits a triple encryption with two keys maybe used.
6.2 What is the meet in the middle attack?
It's that attack doesn't depend on any particular property of the DES, instead, it will work against any type of block ciphers.
For the double-DES cipher & a given (P,C) pair, this attack works as follow:
1. Encrypt the plaintext P with all possibilities of K1, store the results in a table, & sort that table by the value of X.
2. Decrypt C with all possible values of K2, check each resulted value with the entries in the table, in case of match, check these two keys against another known pair (P1,C1), if match, accept them as the correct keys.
6.4 Why is the middle portion of 3DES is a decryption rather than an encryption ?
1. It's a decryption process in order to change the traditional nature of the DES, if it's an encryption, it'll stay a DES but with longer key size....