The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Im Jahre 1977 wurde der „Data Encryption Algorithm“ (DEA) vom „National Bureau of Standards“ (NBS, später „National Institute of Standards and Technology“ – NIST) zum amerikanischen Verschlüsselungsstandard für Bundesbehörden erklärt [NBS_77]. 1981 folgte die Verabschiedung der DEA-Spezifikation als ANSI-Standard „DES“ [ANSI_81]. Die Empfehlung des DES als StandardVerschlüsselungsverfahren wurde auf fünf Jahre befristet und 1983, 1988 und 1993 um jeweils weitere fünf Jahre verlängert. Derzeit liegt eine Neufassung des NISTStandards vor [NIST_99], in dem der DES für weitere fünf Jahre übergangsweise zugelassen sein soll, aber die Verwendung von Triple-DES empfohlen wird: eine dreifache Anwendung des DES mit drei verschiedenen Schlüsseln (effektive Schlüssellänge: 168 bit) [NIST_99]. Der DES basiert auf einer von Horst Feistel bei IBM entwickelten Blockchiffre („Lucipher“) mit einer Schlüssellänge von 128 bit. Da die amerikanische „National Security Agency“ (NSA) dafür gesorgt hatte, daß der DES eine Schlüssellänge von lediglich 64 bit besitzt, von denen nur 56 bit relevant sind, und spezielle Substitutionsboxen (den „kryptographischen Kern“ des Verfahrens) erhielt, deren Konstruktionskriterien von der NSA nicht veröffentlicht wurden, war das Verfahren von Beginn an umstritten. Kritiker nahmen an, daß es eine geheime „Trapdoor“ in dem Verfahren gäbe, die der NSA eine OnlineEntschlüsselung auch ohne Kenntnis des Schlüssels erlauben würde. Zwar ließ sich dieser Verdacht nicht erhärten, aber sowohl die Zunahme von Rechenleistung als auch die Parallelisierung von Suchalgorithmen machen heute eine Schlüssellänge von 56 bit zum Sicherheitsrisiko. Zuletzt konnte 1998 mit einer von der „Electronic Frontier Foundation“ (EFF) entwickelten Spezialmaschine mit 1.800 parallel arbeitenden, eigens entwickelten Krypto-Prozessoren ein DES-Schlüssel in einer Rekordzeit von 2,5 Tagen gefunden werden. Um einen Nachfolger für den DES zu finden, kündigte das NIST am 2. Januar 1997 die Suche nach einem „Advanced Encryption Standard“ (AES) an. Ziel dieser Initiative ist, in enger Kooperation mit Forschung und Industrie ein symmetrisches Verschlüsselungsverfahren zu finden, das geeignet ist, bis weit ins 21. Jahrhundert hinein amerikanische Behördendaten wirkungsvoll zu verschlüsseln. Dazu wurde am 12. September 1997 ein offizieller „Call for Algorithm“ ausgeschrieben. An die vorzuschlagenden symmetrischen Verschlüsselungsalgorithmen wurden die folgenden Anforderungen gestellt: nicht-klassifiziert und veröffentlicht, weltweit lizenzfrei verfügbar, effizient implementierbar in Hardund Software, Blockchiffren mit einer Blocklänge von 128 bit sowie Schlüssellängen von 128, 192 und 256 bit unterstützt. Auf der ersten „AES Candidate Conference“ (AES1) veröffentlichte das NIST am 20. August 1998 eine Liste von 15 vorgeschlagenen Algorithmen und forderte die Fachöffentlichkeit zu deren Analyse auf. Die Ergebnisse wurden auf der zweiten „AES Candidate Conference“ (22.-23. März 1999 in Rom, AES2) vorgestellt und unter internationalen Kryptologen diskutiert. Die Kommentierungsphase endete am 15. April 1999. Auf der Basis der eingegangenen Kommentare und Analysen wählte das NIST fünf Kandidaten aus, die es am 9. August 1999 öffentlich bekanntmachte: MARS (IBM) RC6 (RSA Lab.) Rijndael (Daemen, Rijmen) Serpent (Anderson, Biham, Knudsen) Twofish (Schneier, Kelsey, Whiting, Wagner, Hall, Ferguson).

Advanced Encryption Standard (AES).

Image analysis and machine learning for detecting malaria

Advances in neural information processing systems 3

The Hill cipher algorithm is one of the symmetric key algorithms that have several advantages in data encryption. But, the inverse of the key matrix used for encrypting the plaintext does not always exist. Then if the key matrix is not invertible, then encrypted text cannot be decrypted. In the Involutory matrix generation method the key matrix used for the encryption is itself invertible. So, at the time of decryption we need not to find the inverse of the key matrix. The objective of this paper is to encrypt an image using a technique different from the conventional Hill Cipher. In this paper a novel advanced Hill (AdvHill) encryption technique has been proposed which uses an involutory key matrix. The scheme is a fast encryption scheme which overcomes problems of encrypting the images with homogeneous background. A comparative study of the proposed encryption scheme and the existing scheme is made. The output encrypted images reveal that the proposed technique is quite reliable and robust.

Image Encryption Using Advanced Hill Cipher Algorithm

This paper proposes a newly developed multiple grayscale image encryption scheme using cross-coupling of two Piece-wise Linear Chaotic Maps (PWLCM). In this scheme, cross-coupled PWLCM systems are used to perform both the permutation and diffusion operation. The sorted iterated sequences of cross-coupled PWLCM systems are used to perform the row-column diffusion operation, whereas their corresponding indexed sequences are used to execute the row-column permutation operation. The cross-coupled chaotic map improves the discrete dynamics of chaos and avoids the weakness of using a single chaotic map for permutation-diffusion operation. The use of a cross-coupled chaotic map increases the difficulty of cryptanalysis of the cipher image because the cipher output is generated by the mixing of different chaotic orbits. In addition to this, the cross-coupling of a single type of chaotic map (PWLCM system) increases the software and hardware efficiency of the algorithm. As well as, the use of the PWLCM system increases the encryption speed of the algorithm. The proposed technique also uses the Secure Hash Algorithm SHA-256 to resist the algorithm against the known-plaintext attack and the chosen-plaintext attack. Simulation results and security analysis reveals that the proposed algorithm is more encryption efficient and enhances security in multiple cipher images.

Multiple grayscale image encryption using cross-coupled chaotic maps

In this paper, methods of generating self-invertible matrix for Hill Cipher algorithm have been proposed. The inverse of the matrix used for encrypting the plaintext does not always exist. So, if the matrix is not invertible, the encrypted text cannot be decrypted. In the self-invertible matrix generation method, the matrix used for the encryption is itself self-invertible. So, at the time of decryption, we need not to find inverse of the matrix. Moreover, this method eliminates the computational complexity involved in finding inverse of the matrix while decryption.

/pdf/novel-methods-of-generating-self-invertible-matrix-for-hill-31qsq7z700.pdf

Novel Methods of Generating Self-Invertible Matrix for Hill Cipher Algorithm

Nowadays, internet is the medium through which people are sharing digital images. However, security is an issue in sharing of those images. Encryption techniques play an important role for the security of images. In this paper, an efficient colour image encryption scheme is proposed using multiple piece-wise linear chaotic map (PWLCM) systems. The proposed scheme first performs two-times multi-way block-based rotational permutation operations and then row-column rotational permutations. Finally, it performs row, column, and block diffusion operations. This scheme is simple and secure because it involves only simple rotational permutation operations using only PWLCM systems. Also, this scheme is efficient because it requires less computations and less simulation time to encrypt colour images. The advantages of this scheme are high key space, high security, simplicity and high efficiency in terms of computational complexity and simulation time. The simulation outputs and the security analyses indicate that the proposed method has better performance in terms of encryption efficiency, security, and resistivity for most of the common attacks.

An efficient colour image encryption scheme based on 1-D chaotic maps

In recent days, there is a high demand of encryption of multiple digital images for secure transmission of multiple images. This paper proposes a multi-level permutation operation based secure multiple colour image encryption technique which is totally different than the currently used multiple image encryption techniques. The proposed encryption technique uses three levels of permutation operation: the first level of permutation operation performs pixel-shuffling operations in R, G, and B components, itself; the second level of permutation operation performs row-shuffling operations in between the pixel-shuffled R, G, and B components; the third level of permutation operation performs column-shuffling operations in between the row-shuffled components. At last, the proposed encryption algorithm performs block-diffusion operations to get the final encrypted images. Multi-level permutation operations and diffusion operation only use PWLCM systems multiple times to make the algorithm more secure and stronger. Multiple PWLCM systems in multi-level permutation operations not only produces larger key space and higher key sensitivity but also generates greater randomness of pixels and weaker correlation of adjacent pixels in images as compared to the currently used multiple image encryption techniques. In addition the secret keys which are used in this proposed algorithm not only depends on the original key values but also depends on the original colour images. This protects the algorithm against known-plaintext attack and chosen-plaintext attack. The simulation results and the security analysis indicate that the proposed algorithm has good encryption results, large secret-key space, higher sensitivity towards secret keys and the plaintext, weaker correlation of adjacent pixels, greater randomness of pixels, and enough resistance against various common attacks.

Bibhudendra Acharya

Papers

Image Encryption Using Advanced Hill Cipher Algorithm

Multiple grayscale image encryption using cross-coupled chaotic maps

Novel Methods of Generating Self-Invertible Matrix for Hill Cipher Algorithm

An efficient colour image encryption scheme based on 1-D chaotic maps

Secure multi–level permutation operation based multiple colour image encryption