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Key Scheduling in DES Type Cryptosystems
 in Advances in Cryptology: Auscrypt '90 (Lecture Notes in Computer Science
, 1990
"... This paper reviews some possible design criteria for the key schedule in a DES style cryptosystem. The key schedule involves a Key Rotation component, and the permutation PC2. Together these provide for a diffusion of dependency ofciphertext bits on key bits. Some empirical rules which seem to accou ..."
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This paper reviews some possible design criteria for the key schedule in a DES style cryptosystem. The key schedule involves a Key Rotation component, and the permutation PC2. Together these provide for a diffusion of dependency ofciphertext bits on key bits. Some empirical rules which seem to account for the derivation of the key schedule used in the DES are first presented. Anumber of trials were run with various key schedules, and some further design rules were derived. An alternative form of key schedule was then tested. This used either a null PC2, or one in which permutations only occurred within the inputs to a given Sbox, and a much larger rotation schedule than used in the DES. This was found to be as effective as the key schedule used in the current DES, and is proposed for use in new cryptosystems. 1.
On the Design of Permutation P in DES Type Cryptosystems
 Advances in Cryptology: Proceedings of EUROCRYPT ’89
, 1990
"... This paper reviews some possible design criteria for the permutation P in a DES style cryptosystem. These permutations provide the diffusion component in a substitutionpermutation network. Some empirical rules which seem to account for the derivation of the permutation used in the DES are first pre ..."
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Cited by 7 (3 self)
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This paper reviews some possible design criteria for the permutation P in a DES style cryptosystem. These permutations provide the diffusion component in a substitutionpermutation network. Some empirical rules which seem to account for the derivation of the permutation used in the DES are first presented. Then it is noted that these permutations may be regarded as latinsquares which link the outputs of Sboxes to their inputs at the next stage. A subset of these with an extremely regular structure, and which perform well in a dependency analysis are then presented and suggested for use in future schemes of both current and extended versions of the DES. 1.
A Generalised Testbed for Analysing Block and Stream Ciphers
 in Proceedings of the Seventh In tern a tion IFIP TC1l Conference on Information Security
, 1991
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Disciplines
, 1991
"... A generalised testbed for analysing block and stream ciphers ..."
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Revisiting Key Schedule’s Diffusion In Relation With Round Function’s Diffusion
"... Abstract. We study the weakness of key schedules from an observation: many existing attacks use the fact that the key schedules poorly distribute key bits in the diffusion path of round function. This reminds us of the importance of the diffusion’s relation between key schedule and round function. W ..."
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Abstract. We study the weakness of key schedules from an observation: many existing attacks use the fact that the key schedules poorly distribute key bits in the diffusion path of round function. This reminds us of the importance of the diffusion’s relation between key schedule and round function. We present new cryptanalysis results by exploring such diffusion relation and propose a new criterion for necessary key schedule diffusion. We discuss potential attacks and summarize the causes for key schedules without satisfying this criterion. One major cause is that overlapping between the diffusion of key schedule and round function leads to information leakage of key bits. Finally, a measure to estimate our criterion for recursive key schedules is presented. Today designing key schedule still lacks practical and necessary principles. For a practical key schedule with limited diffusion, our work adds more insight to its requirements and helps to maximize the security level. 1
Australian Defence Force Academy,
"... The Data Encryption standard (DES) has achieved wide utilization, especially in the financial industry. Whilst DES is a standard, the design criteria used in its development have been classified by the US government. This paper reviews what is known about the design criteria for the Sboxes, Pboxes ..."
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The Data Encryption standard (DES) has achieved wide utilization, especially in the financial industry. Whilst DES is a standard, the design criteria used in its development have been classified by the US government. This paper reviews what is known about the design criteria for the Sboxes, Pboxes, and key scheduling in the current DES. It then indicates how this information could be used to design an extended scheme with a double length key. There are two main objectives indoing this. One is because of increasing doubts about the ability of DES to withstand an attack based on exhaustive keyspace searches, using specialized hardware. The other is to develop an encryption scheme for which the design rules used are known, and hence open to analysis and criticism.
DES80
"... In the Fall of 1996, the Canadian Government issued a request for a study on the feasibility of strengthening the Data Encryption Standard (DES) by increasing the key length to 80 bits. What made this request both interesting and challenging was the overall constraint placed on the project: there wa ..."
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In the Fall of 1996, the Canadian Government issued a request for a study on the feasibility of strengthening the Data Encryption Standard (DES) by increasing the key length to 80 bits. What made this request both interesting and challenging was the overall constraint placed on the project: there was to be no change whatsoever made to the actual encryption / decryption algorithm; rather, changes were to be confined solely to the key scheduling algorithm. Any method may be used to input and process the (maximum) 80bit primary key, but the result of the process must be sixteen 48bit round keys suitable for keying the DES rounds in the standard manner.
Des80
"... In the Fall of 1996, the Canadian Government issued a request for a study on the feasibility of strengthening the Data Encryption Standard (DES) by increasing the key length to 80 bits. What made this request both interesting and challenging was the overall constraint placed on the project: there wa ..."
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In the Fall of 1996, the Canadian Government issued a request for a study on the feasibility of strengthening the Data Encryption Standard (DES) by increasing the key length to 80 bits. What made this request both interesting and challenging was the overall constraint placed on the project: there was to be no change whatsoever made to the actual encryption / decryption algorithm; rather, changes were to be confined solely to the key scheduling algorithm. Any method may be used to input and process the (maximum) 80bit primary key, but the result of the process must be sixteen 48bit round keys suitable for keying the DES rounds in the standard manner. This paper summarizes the results of the above study, including a new key scheduling algorithm that appears to satisfy all requirements of the DES80 project. The full report (dated May 2, 1997) is the property of the Canadian Government. 2. Introduction The Data Encryption Standard (DES) is perhaps the most widely known and widely use...