Showing papers on "Two-square cipher published in 1997"
20 Jan 1997
TL;DR: This paper cryptanalyse 5 rounds of a variant of SHARK, which deviates only slightly from the proposed SHark, and shows that there exist ciphers constructed according to this design strategy which can be broken faster than claimed.
Abstract: In this paper we introduce a new method of attacks on block ciphers, the interpolation attack. This new method is useful for attacking ciphers using simple algebraic functions (in particular quadratic functions) as S-boxes. Also, ciphers of low non-linear order are vulnerable to attacks based on higher order differentials. Recently, Knudsen and Nyberg presented a 6-round prototype cipher which is provably secure against ordinary differential cryptanalysis. We show how to attack the cipher by using higher order differentials and a variant of the cipher by the interpolation attack. It is possible to successfully cryptanalyse up to 32 rounds of the variant using about 232 chosen plaintexts with a running time less than 264. Using higher order differentials, a new design concept for block ciphers by Kiefer is also shown to be insecure. Rijmen et al presented a design strategy for block ciphers and the cipher SHARK. We show that there exist ciphers constructed according to this design strategy which can be broken faster than claimed. In particular, we cryptanalyse 5 rounds of a variant of SHARK, which deviates only slightly from the proposed SHARK.
378 citations
20 Jan 1997
TL;DR: It is demonstrated that for certain block ciphers, trapdoors can be built-in that make the cipher susceptible to linear cryptanalysis; however, finding these trapdoor can be made very hard, even if one knows the general form of the trapdoor.
Abstract: This paper presents several methods to construct trapdoor block ciphers. A trapdoor cipher contains some hidden structure; knowledge of this structure allows an attacker to obtain information on the key or to decrypt certain ciphertexts. Without this trapdoor information the block cipher seems to be secure. It is demonstrated that for certain block ciphers, trapdoors can be built-in that make the cipher susceptible to linear cryptanalysis; however, finding these trapdoors can be made very hard, even if one knows the general form of the trapdoor. In principle such a trapdoor can be used to design a public key encryption scheme based on a conventional block cipher.
59 citations
24 Sep 1997
TL;DR: The BEAST cipher as mentioned in this paper is a new blockcipher for arbitrary size blocks, which is a Luby-Rackoff cipher and fast when the blocks are large, and it is provably secure if these building blocks are secure.
Abstract: This paper describes BEAST, a new blockcipher for arbitrary size blocks. It is a Luby-Rackoff cipher and fast when the blocks are large. BEAST is assembled from cryptographic hash functions and stream ciphers. It is provably secure if these building blocks are secure.
27 citations
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TL;DR: SPEED is a private key block cipher that supports three variable parameters: data length, key length and rounds.
Abstract: SPEED is a private key block cipher. It supports three variable parameters: (1) data length — the length of a plaintext/ciphertext of SPEED can be 64, 128 or 256 bits. (2) key length — the length of an encryption/decryption key of SPEED can be any integer between 48 and 256 (inclusive) and divisible by 16. (3) rounds — the number of rounds involved in encryption/decryption can be any integer divisible by 4 but not smaller than 32.
22 citations
TL;DR: The results of security analysis show that the hash function can be expected to have ideal computational security against the five attacks when the underlying cipher is assumed to have no weakness.
Abstract: A new 2m-bit iterated hash function based on an m-bit block cipher with a 2m-bit key is presented. The results of security analysis show that the hash function can be expected to have ideal computational security against the five attacks when the underlying cipher is assumed to have no weakness.
17 citations
TL;DR: The author examines the application of linear cryptanalysis to the RC5 private-key cipher and shows that there are expected to be weak keys for which the attack is applicable to many rounds, highlighting the sensitivity of RC5 security to its key scheduling algorithm.
Abstract: The author examines the application of linear cryptanalysis to the RC5 private-key cipher and shows that there are expected to be weak keys for which the attack is applicable to many rounds. It is demonstrated that, for the 12-round nominal RC5 version with a 64 bit block size and a 128 bit key, there are 2/sup 28/ weak keys for which only /spl sim/2/sup 17/ known plaintexts are required to break the cipher. There are 268 keys for which the cipher is theoretically breakable, requiring /spl sim/2/sup 57/ known plaintexts. The analysis highlights the sensitivity of RC5 security to its key scheduling algorithm.
7 citations
25 May 1997
TL;DR: A new class of unbalanced CAST ciphers which employ the same structure of S box and round function as the original CAST cipher but has a lower memory requirement are presented.
Abstract: The original CAST cipher is an efficient and secure private key block cipher designed to be an alternative to DES. We present a new class of unbalanced CAST ciphers which employ the same structure of S box and round function as the original CAST cipher but has a lower memory requirement. Furthermore, we investigate the security of the ciphers with respect to differential and linear cryptanalysis. The result of analysis shows that unbalanced CAST ciphers with appropriate parameters are resistant to differential and linear cryptanalysis.
3 citations
Dissertation•
1 Jan 1997
TL;DR: It is suggested that the maximum static and dynamic input-output bit information leakages for the unbalanced CAST ciphers constructed by 8 x 32 S-boxes are much smaller than for DES.
Abstract: The original CAST cipher is an efficient and secure private-key block cipher designed to be an alternative to the Data Encryption Standard (DES). In this thesis, we present a new class of unbalanced CAST ciphers which employs the same structure of S-box and round function of the original CAST cipher but has a lower memory requirement. Unbalanced CAST ciphers with one or two 8x32 S-boxes in the round function require only 1/4 or 1/2 the memory of the original CAST cipher, respectively. -- This thesis examines the application of differential and linear cryptanalysis, two of the most powerful methodologies for attacking private-key block ciphers, to the unbalanced CAST ciphers. The results of analysis show that a 48-round unbalanced CAST cipher with one 8 x 32 S-box and a 24-round unbalanced CAST cipher with two 8 x 32 S-boxes, both of which are equivalent to a 12-round original CAST cipher in efficiency, are resistant to both differential and linear cryptanalysis. -- We also investigate the unbalanced CAST ciphers from the perspective of information theory. The results suggest that the maximum static and dynamic input-output bit information leakages for the unbalanced CAST ciphers constructed by 8 x 32 S-boxes are much smaller than for DES. -- The conclusion reached by the thesis is that unbalanced CAST ciphers can be considered to be efficient, secure ciphers which require less memory than the original CAST cipher.
3 citations
Journal Article•
TL;DR: A receiver sheet for electrostatic recording comprises a dense paper base sheet having a bulk porosity of less than 200 Sheffield units as measured by a Sheffield Porosimeter, and a preferred conductive coat, which can be applied from aqueous dispersion or solution without adversely affecting resistivity of the dielectric coat.
Abstract: A receiver sheet for electrostatic recording comprises a dense paper base sheet having a bulk porosity of less than 200 Sheffield units as measured by a Sheffield Porosimeter with a 1 1/2 inch orifice and air at 1 1/2 psi; a thin first conductive coat on one side of the paper base containing 20 to 30 percent by weight of conductive material, distributed so as to provide the conductive material in a coat weight of 0.05 to 0.25 pound per 1000 sq/ft. of paper; a dielectric coat on top of the first conductive coat, having a surface resistivity greater than 1 x 1016 ohms per square at 20% relative humidity; and a second conductive coat on the opposite side of the paper base. A preferred conductive coat comprises a vinylbenzyl quaternary ammonium compound mixed with a starch derivative binder and coating clay. Both the first conductive coat and the dielectric coat can be applied from aqueous dispersion or solution without adversely affecting resistivity of the dielectric coat.
1 citations
1 Jan 1997
TL;DR: There is described a class of the encryption functions based on data-dependent selection of subkeys that are proposed for elaboration of the indeterminate ciphers with very large number of dierent modifications of the cryptalgorithm.
Abstract: There is described a class of the encryption functions based on data-dependent selection of subkeys. Such functions are proposed for elaboration of the indeterminate ciphers with very large number of dierent modifications of the cryptalgorithm. A 128bit undetermined cipher is described. The number of possible modifications is … 10 20R , where 2 • R • 7, R is the number of
17 Sep 1997
TL;DR: In this article, a byte-oriented block cipher with a key of length 64 bits is proposed, which is composed of two simple operations (exclusive-or and addition) and three cryptographically strong S-boxes (one is 8 x 8 S-box, two are 8-bit involution Sbox) to provide necessary confusion and diffusion and facilitate both hardware and software implementation.
Abstract: In this paper, a new byte-oriented block cipher with a key of length 64 bits is proposed. In the proposed cipher, the block length is 64 bits and only byte operations are utilized. The cipher structure is composed of two simple operations (exclusive-or and addition) and three cryptographically strong S-boxes (one is 8 x 8 S-box, two are 8-bit involution S-boxes) and chosen to provide necessary confusion and diffusion and facilitate both hardware and software implementation. The design principles of the proposed cipher are explained and a sample data is given.
TL;DR: An efficient set of statistical methods for analysing the security of these algorithms under the black-box approach can be fully automated, which provides the designer or user of a block cipher with a useful set of tools for security analysis.
Abstract: A block cipher is one of the most common forms of algorithms used for data encryption. This paper describes an efficient set of statistical methods for analysing the security of these algorithms under the black-box approach. The procedures can be fully automated, which provides the designer or user of a block cipher with a useful set of tools for security analysis.