Patent•
Enhanced block ciphers with data-dependent rotations
15 Jun 1998-
TL;DR: A plaintext message to be encrypted is segmented into a number of words, and an integer multiplication function is applied to a subset of the words, e.g., to the two words in registers B and D as mentioned in this paper.
Abstract: A plaintext message to be encrypted is segmented into a number of words, e.g., four words stored in registers A, B, C and D, and an integer multiplication function is applied to a subset of the words, e.g., to the two words in registers B and D. The integer multiplication function may be a quadratic function of the form ƒ(x)=x(ax+b) or other suitable function such as a higher-order polynomial. The results of the integer multiplication function are rotated by lg w bits, where lg denotes log base 2 and w is the number of bits in a given word, to generate a pair of intermediate results t and u. An exclusive-or of another word, e.g., the word in register A, and one of the intermediate results, e.g., t, is rotated by an amount determined by the other intermediate result u. Similarly, an exclusive-or of the remaining word in register D and the intermediate result u is rotated by an amount determined by the other intermediate result t. An element of a secret key array is applied to each of these rotation results, and the register contents are then transposed. This process is repeated for a designated number of rounds to generate a ciphertext message. Pre-whitening and post-whitening operations may be included to ensure that the input or output does not reveal any internal information about any encryption round. Corresponding decryption operations may be used to decrypt the ciphertext message.
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Patent•
29 Oct 2007
TL;DR: In this article, a dynamic credit card is provided in which a secret/hidden credit card number is encoded based on a timing signal (e.g., an internal counter) to provide a dynamic card number.
Abstract: A dynamic credit card is provided in which a secure credit card number (e.g., a secret/hidden credit card number) is encoded based on a timing signal (e.g., an internal counter) to provide a dynamic credit card number. This dynamic number may be displayed to a user via a display (e.g., so that online purchases can be made) or written onto a magnetic stripe such that the number may be processed by traditional credit card merchants (e.g., swiped). At a remote facility, the dynamic number may be decoded based on time (and/or a counter/key number/equation) or the facility may have the secure number and perform the same function as the dynamic credit card (e.g., encode using time data as a parameter to the encoding equation) and compare the resultant dynamic number to the dynamic number received. Thus, a dynamic credit card number may change continually or periodically (e.g., every sixty seconds) such that credit card numbers may not be copied by thieves and used at later times. A dynamic verification code may be utilized in addition to, or in lieu of, a dynamic credit card number.
326 citations
Patent•
19 Dec 2008
TL;DR: In this article, a payment card (e.g., credit and/or debit card) or other device is provided with a magnetic emulator operable to communicate data to a magnetic stripe read-head.
Abstract: A payment card (e.g., credit and/or debit card) or other device (e.g., mobile telephone) is provided with a magnetic emulator operable to communicate data to a magnetic stripe read-head. Data may include the type of reward that a user would like to earn as a result of making a purchase or the type of reward that a user would like to utilize to at least partially pay for a purchase.
187 citations
Patent•
[...]
29 Nov 2000
TL;DR: In this article, a data encryption system for encrypting an n-bit block of input in a plurality of rounds is presented, where n is preferably 128 bits or more, and the system includes a computing unit for the execution of each round; memory for storing and loading segments; a bit-moving function capable of rotating, shifting, or bit-permute round segments by predetermined numbers of bits preferably to achieve active and effective fixed rotation; a linear combination function which provides new one-to-one round segments using a round operator generally from one algebraic group to combine two different
Abstract: A data encryption system for encrypting an n-bit block of input in a plurality of rounds is presented, where n is preferably 128 bits or more. The data encryption system includes a computing unit for the execution of each round; memory for storing and loading segments; a bit-moving function capable of rotating, shifting, or bit-permute round segments by predetermined numbers of bits preferably to achieve active and effective fixed rotation; a linear combination function which provides new one-to-one round segments using a round operator generally from one algebraic group to combine two different one-to-one round segments taken from one one-to-one round segment set; and a nonlinear function which affects a one-to-one round segment from a particular one-to-one round segment set based on a value which depends on a preselected number of bits in a preselected location from a different one-to-one round segment from the same one-to-one round segment set. The nonlinear function is a variable rotation function or an s-box. A subkey combining function is generally employed in each round to provide new round segments by combining a round segment typically linearly with a subkey segment.
175 citations
Patent•
13 May 2005
TL;DR: In this article, a user successfully logs in to an information server (22, 104) such as an online banking server, an e-commerce server, or a VPN server, for greater security communication is transferred transparently to the user to an authentication server (106) for additional authentication.
Abstract: When a user successfully logs in to an information server (22, 104) such as an online banking server, an e-commerce server, or a VPN server, for greater security communication is transferred transparently to the user to an authentication server (106) for additional authentication. The additional authentication can include comparing elements of a previously deposited cookie on the user computer (12, 102) to test elements, and if the elements match, granting access and transparently transferring the user computer (12, 102) back to the information server (22, 104). If the secondary authentication fails, however, the user may be asked questions as tertiary authentication, or a PIN code can be sent to the user's cell phone, which PIN code can then be input on the user computer (12, 102) to gain access.
154 citations
Patent•
27 Apr 2006TL;DR: In this article, a method for manufacturing an electronic card having at least two components is presented, where the processor and batter are essentially coplanar, and are sandwiched between and enclosed by two flexible covers.
Abstract: An electronic card (10) includes a digital processor, an electromechemical battery and a communication port. The processor and batter are essentially coplanar, and are sandwiched between and enclosed by two flexible covers (12, 14), preferably made from an insulating plastic material, and preferably fitted to the components that they enclose. The communications port can include, for example, a Smart Card contact port, a stripe emulator, an RF port, and IR port, etc. The battery may comprise a rechargeable battery. In an exemplary embodiment, at least the processor is carried by a flexible printed circuit (PC board). In another exemplary embodiments, switches and/or indicators are also carried by the PC board. A method for manufacturing an electronic card having at least two components is also disclosed.
130 citations
References
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Book•
10 Nov 1993
TL;DR: This document describes the construction of protocols and their use in the real world, as well as some examples of protocols used in the virtual world.
Abstract: CRYPTOGRAPHIC PROTOCOLS. Protocol Building Blocks. Basic Protocols. Intermediate Protocols. Advanced Protocols. Esoteric Protocols. CRYPTOGRAPHIC TECHNIQUES. Key Length. Key Management. Algorithm Types and Modes. Using Algorithms. CRYPTOGRAPHIC ALGORITHMS. Data Encryption Standard (DES). Other Block Ciphers. Other Stream Ciphers and Real Random-Sequence Generators. Public-Key Algorithms. Special Algorithms for Protocols. THE REAL WORLD. Example Implementations. Politics. SOURCE CODE.source Code. References.
3,432 citations
02 Jan 1994
TL;DR: A new method is introduced for cryptanalysis of DES cipher, which is essentially a known-plaintext attack, that is applicable to an only-ciphertext attack in certain situations.
Abstract: We introduce a new method for cryptanalysis of DES cipher, which is essentially a known-plaintext attack. As a result, it is possible to break 8-round DES cipher with 221 known-plaintexts and 16-round DES cipher with 247 known-plaintexts, respectively. Moreover, this method is applicable to an only-ciphertext attack in certain situations. For example, if plaintexts consist of natural English sentences represented by ASCII codes, 8-round DES cipher is breakable with 229 ciphertexts only.
2,753 citations
14 Dec 1994
TL;DR: This document describes the RC5 encryption algorithm, a fast symmetric block cipher suitable for hardware or software implementations and a novel feature of RC5 is the heavy use of data-dependent rotations.
Abstract: This document describes the RC5 encryption algorithm, a fast symmetric block cipher suitable for hardware or software implementations. A novel feature of RC5 is the heavy use of data-dependent rotations. RC5 has a variable word size, a variable number of rounds, and a variable-length secret key. The encryption and decryption algorithms are exceptionally simple.
894 citations
Patent•
21 Dec 1989TL;DR: In this paper, a method and apparatus for encrypting and decrypting data which operates efficiently on computers of differing architectures is disclosed, which uses part of the data input to access a table of pseudo-random numbers.
Abstract: A method and apparatus for encrypting and decrypting data which operates efficiently on computers of differing architectures is disclosed. Unlike previous encryption/decryption method and apparatus, the present invention executes efficiently in the computer's software. The method uses part of the data input to access a table of pseudo-random numbers. The pseudo-random numbers are exclusively ORed (XORed) with the remaining part of the data input. The output from the XOR operation is then used to access the table where the other portion of the data is in turn XORed with the pseudo random numbers. This iterative process continues until the data is fully randomized. Several variations of this method are presented.
160 citations
Patent•
07 Oct 1992
TL;DR: In this article, a two-key cryptosystem for communication and electronic signatures is described, where the private decoding key is not feasibly determinable from the associated public encoding key, and the ciphertext is deciphered with a secret key known only to the intended receiver.
Abstract: A cryptographic method for communication and electronic signatures is described. The system includes at least one encoding device coupled to at least one decoding device by a communications channel. The method is a form of public-key or two-key cryptosystem, where the private decoding key is not feasibly determinable from the associated public encoding key. A block of ns bits of a message-to-be-transferred M (or key-to-be-distributed) is enciphered to ciphertext by first mapping M to a set {x 1 , x 2 , . . . , x n }, where x i [0, 2 s ). Then the ciphertext {y 1 , y 2 , . . . , y m } is determined by ##EQU1## mod q j , for j=1 to m', and ##EQU2## for j=m'+1 to m, where ##EQU3## The encoding key (associated with the intended receiver) consists of integers a ij , g j , and positive fractions f i , for i=1 to n and for j=1 to m, and positive integers q j , for j=1 to m'. The ciphertext is deciphered (with a secret key known only to the intended receiver) by solving a knapsack ##EQU4## with secret superincreasing weights {b 1 , b 2 , . . . , b n } and target value b≡|w -1 |w' -1 y| Q | P , where y≡{y 1 , y 2 , . . . , y m } mod {q 1 , q 2 , . . . , q m }, ##EQU5## and w, w', and {q m'+1 , q m'+2 , . . . , q m } are secret integers. The resulting terms {x' 1 , x' 2 , . . . , x' n } correspond to the original message terms {x 1 , x 2 , . . . , x n }.
131 citations