Showing papers on "Cipher published in 1981"

On the security of multiple encryption

Abstract: Double encryption has been suggested to strengthen the Federal Data Encryption Standard (DES). A recent proposal suggests that using two 56-bit keys but enciphering 3 times (encrypt with a first key, decrypt with a second key, then encrypt with the first key again) increases security over simple double encryption. This paper shows that although either technique significantly improves security over single encryption, the new technique does not significantly increase security over simple double encryption. Cryptanalysis of the 112-bit key requires about 256 operations and words of memory, using a chosen plaintext attack. While DES is used as an example, the technique is applicable to any similar cipher.

Crypto microprocessor that executes enciphered programs

Abstract: A microprocessor for executing computer programs which are stored in cipher to prevent software piracy. Such a crypto-microprocessor deciphers the enciphered program piecemeal as it executes it, so that a large enciphered program can be securely executed without disclosing the deciphered program or associated data to persons who have access to the wiring of the computer in which the crypto-microprocessor is a component. Such a device may process valuable proprietary programs and data files which are distributed in cipher on videodiscs, semiconductor memory, or other media without risk of software piracy. Various methods of encryption may be used including methods which result in the cipher of a byte being a complicated function of the byte's address in memory. Each crypto-microprocessor chip may use a unique cipher key or tables for deciphering the program, so that a program that can be executed in one chip cannot be run in any other microprocessor.

Cryptographic decoder for computer programs

Abstract: An integrated circuit decoder for providing microcomputer users with access to several proprietary programs selected from a large group of such programs that have been distributed to users in cipher. The decoder chip can decipher a program if an enciphered key called a "permit code" is presented to the decoder chip. Permit codes are not interchangeable between decoders, are issued only to customers that have paid for use of a program product, and each code will work only with one program. As the program is being deciphered in a user's microcomputer, the decoder chip places random errors into the program which make copies of the program malfunction in other microcomputers. The decoder chip keeps a table of addresses where it has placed errors and dynamically corrects the errors on the data bus whenever an error word is addressed during execution. Using such a decoder, thousands of individually priced proprietary software products can be delivered securely to prospective customers in advance of sales on laserdiscs, diskettes, TV-cables, and digital radio broadcasts.

How Polish Mathematicians Broke the Enigma Cipher

Abstract: The paper gives a personal view of work in the Polish Cipher Bureau from 1932 to 1939 as mathematicians worked to decipher the codes of the military version of the Enigma. The author, who was a participant, relates details of the device and the successes and frustrations involved in the work. He also describes mathematical principles that enabled him and his colleagues to break successive versions of the Enigma code and to construct technical devices (cyclometers and "bombs") that facilitated decipherment of Enigma-coded messages.

Video cipher processing system

Abstract: A video cipher processing system comprising a detecting means for detecting average tone variation of TV video signals, an extracting means for extracting at random at least some of outputs from the detecting means as a result of the detection and a ciphering means for ciphering video signals by inverting or non-inverting polarities of video signals in response to outputs extracted at random by the extracting means.

The genesis of the jefferson/bazeries cipher device

Abstract: Cipher Device M-94 was adopted by the United States Army in 1922, the same year papers found in the Library of Congress revealed that Thomas Jefferson had invented the same device about 125 years earlier. Almost 100 years after Jefferson, Commandant Etienne Bazeries, a French army cryptologist, independently developed a similar device. Both inventions, which ultimately formed the basis for the most widely used cryptosystems in the 20th century, apparently had a common antecedent in the letter lock, which was popularized in France by Edme Regnier during the late 18th and early 19th centuries.

Graphic solution of a linear transformation cipher

Abstract: (1981). GRAPHIC SOLUTION OF A LINEAR TRANSFORMATION CIPHER. Cryptologia: Vol. 5, No. 1, pp. 1-19.

The hand-held calculator as a cryptographic machine

Abstract: The degree of sophistication available in today's programmable personal calculators may be used to provide a practical field cipher capability of significant power. Procedures are presented for key management, key generator cycling alarm, cipher-type selection to match cryptanalytic threat level, and key length options as an answer to key-search attacks. Three basic cipher procedures are presented with special emphasis given to the inherent power of transposition techniques. Four cryptogram examples are included to demonstrate four of the levels of available security offered by the system.

Measuring cryptographic performance with production processes

Abstract: A measure of complexity based on production processes is presented as a measure of the resistance of a given cipher to cryptanalysis. Complexity calculations for several ciphers are presented and discussed.

Higher-order homophonic ciphers

Abstract: In a recent paper, James J. Gillogly [1] asserts that Beale Cipher No. 1 is spurious. We take no issue with his statistics but wish to point out that he has missed an important alternative: Higher—Order Homophonics. We provide here an overview of second – and higher-order homophonic enciphering/deciphering principles and apply this concept to a further analysis of the Beale Ciphers. We shall finally suggest that the Beale Ciphers should not readily be dismissed as a hoax, as J. J. Gillogly, Greg Mellen [2,3] and others would have us do.

Processing device of window transaction

Abstract: PURPOSE:To enhance the efficiency of window business and prevent the leakage of cipher numbers etc. by enabling the customer himself to input his magnetic card and cipher number at the time of performing transaction at the window by using an on-line banking system. CONSTITUTION:A customer 5 has a magnetic card 8 read in a magnetic card read part 3. Next, a cipher number 16 is inputted from a cipher input part 4. This cipher number 16 is compared and collated with the cipher number in the read data of the magnetic card 8 in an arithmetic control part 11, and when they coincide, the coincidence and the account number of the customer 5 are displayed in a data display output part 12. When the customer's account number is inputted from the data input part 15, the read data of the magnetic card 8 is read out into the arithmetic control part 11 from a memory part 13 and are processed together with the data necessary for the transaction inputted from the data input part 15, in the arithmetic control part 11.

Registration system of electronic cash register

Abstract: PURPOSE:To prevent wrong registration by another's operation by inputting a cipher code for the start of registration after a person in charge and then returns to leaves his or her position and by allowing the registration only when the input code agrees with a previously stored cipher code. CONSTITUTION:A casher, when to leave his or her position during operation, turns off the casher key. Consequently, ''0'', i.e. an unregisterable state is set in registrable-unregisterable state memory part 23 of memory area 21 of RAM. In this state, even if registration information is inputted, the cash register never accepts it. The casher, when returning the position and restarting the registration, turns on the casher key and inputs his or her own cipher code and casher code from ten keys. Next, when the input cipher code agrees with the memory contents of cipher code memory part 24, ''1'' is set in memory part 23 and the registration is allowed. Consequently, even if a htird person tries to perform the registration without permission, the cash register does not accept it, preventing wrong registration.

On Pure and Related Ciphers

Abstract: It is possible to formulate several properties of a cipher that can be said to make the cipher homogeneous with respect to the key, i.e. whatever key used different aspects of the enciphering, deci ...

Data processing system

Abstract: PURPOSE:To realize sending and receiving a secret data to and from each computer center, by calculating a position in the secret data based on both the intrinsic information the the incidental information of each computer center in case of receiving and sending a data between each computer system, and ciphering its position CONSTITUTION:When the electronic computer 1 starts writing to a data relay medium 4, at first it inputs the intrinsic information such as unit manufacturing No of a destined electronic computer 2, etc into the unit intrinsic information register 11d, and subsequently inputs the incidental information of a sending side electronic computer 1 into the register 11a Being based on the contents of the aforesaid two registers 11a, 11d, the cipher preparing means 11s prepares a cipher embedding position and a data for embedment, and the embedding means 11p embeds a designated cipher into a position designated by the means 11s, transfers it to the data buffer 11t, and it is output to the medium 4 by the input/output nameee11x When the electronic computer 2 loads the contents of the medium 4, it calculates a cipher embedding position and a data for embedment by the self-intrinsic information and the incidental information, inspects whether there is a calculated cipher in the loaded data or not, and if it is correct, a data except a cipher is loaded