Showing papers on "Encryption published in 1979"

Crypto microprocessor for executing 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.

Data Security

Abstract: The rising abuse of computers and increasing threat to personal privacy through data banks have stimulated much interest in the technical safeguards for data. There are four kinds of safeguards, each related to but distinct from the others. Access controls regulate which users may enter the system and subsequently which data sets an active user may read or write. Flow controls regulate the dissemination of values among the data sets accessible to a user. Inference controls protect statistical databases by preventing questioners from deducing confidential information by posing carefully designed sequences of statistical queries and correlating the responses. Statistical data banks are much less secure than most people believe. Data encryption attempts to prevent unauthorized disclosure of confidential information in transit or in storage. This paper describes the general nature of controls of each type, the kinds of problems they can and cannot solve, and their inherent limitations and weaknesses. The paper is intended for a general audience with little background in the area.

Symmetric and Asymmetric Encryption

Abstract: All cryptosystems currently m use are symmetrm m the sense that they require the transmitter and receiver to share, m secret, either the same pmce of reformation (key) or one of a paLr of related keys easdy computed from each other, the key is used m the encryption process to introduce uncertainty to an unauthorized receiver. Not only is an asymmetric encryption system one in whmh the transmitter and receiver keys are different, but in addition it Is computatmnally mfeaslble to compute at least one from the other. Asymmetric systems make it possible to authent2cate messages whose contents must be revealed to an opponent or allow a transmitter whose key has been compromised to communmate m privacy to a receiver whose key has been kept secret--neither of which is possible using a symmetric cryptosystem. This paper opens with a brmf dmcussion of encryptmn principles and then proceeds to a comprehensive discussion of the asymmetric encryptmn/decryp tion channel and its application m secure communmations.

Structured Design of Substitution-Permutation Encryption Networks

Abstract: In attempting to solve the problems of data security, researchers, and practititioners are placing increasing emphasis on encryption An important class of encryption schemes is that of substitution-permutation (SP) encryption networks A variant of the SP network has been chosen by the National Bureau of Standards as the data encryption standard In this paper, we introduce the concept of completeness, which captures the intuitive notion of complexity of SP networks The completeness property is examined and a technique for designigning complete SP networks is demonstrated

Method and apparatus for transaction and identity verification

Abstract: A method and apparatus whereby the senders and receivers of messages sent over a transmission system including a Host CPU may guarantee the integrity of the data content of the message and also the absolute identity of the sender. Each user of the system as well as the Host CPU contains an identical key-controlled block-cipher cryptographic device with data chaining for encrypting and decrypting messages as required, wherein each user has knowledge of only his own cryptographic key and wherein the Host CPU has access to the unique cryptographic keys of all users of the system stored in a high security storage area available only to said CPU. Stated very generally, the originator of a message A sends a message to a receiver B which includes a transaction or message portion X and a unique digital signature portion Y which is a function both of the message and the senders unique cryptographic key K A . The receiver then communicates with the CPU for verification of the signature Y. The CPU accesses the sender's key K A from a secure memory and computes the digital signature Y utilizing the message portion X received from B and the key K A . Upon a successful verification of the signatures by the CPU, the CPU notifies B via an additional message that the signature of A is valid based on the data content of the message and the key K A . Based on the information received from the CPU, B may be certain that the signature and message originated with A and A may not later deny having sent the message as it would be virtually impossible for the signature to be forged since it is a complex function of the message content itself. A may also be assured that B cannot alter the message as the signature would no longer be valid. According to other aspects of the invention the interrupting of communications between A and B by an eavesdropper and the subsequent sending of stale messages is prevented. As a still further feature of the invention, an eavesdropper is prevented from sending the "forged" approval from the CPU to the receiver B.

Encryption and Secure Computer Networks

Abstract: There is increasing growth in the number of computer networks in use and in the kinds of distributed computing applications available on these networks This increase, together with concern about privacy, security, and integrity of information exchange, has created considerable interest in the use of encryptlon to protect information in the networks This survey is directed at the reader who ts knowledgeable about varmus network designs and who now wishes to consider incorporating encryption methods into these designs. It is also directed at developers of encryption algorithms who wish to understand the characteristics of such algorithms useful in network applications. Key management, network encryption protocols, digital signatures, and the utility of conventionalor public-key encryptlon methods are each discussed. A case study of how encryption was integrated into an actual network, the Arpanet, illustrates many issues present m the design of a network encryption facdity.

Method and apparatus for securing data transmissions

Abstract: A method and apparatus are provided for improving the security of data transmissions between stations. The method obviates the need for transmitting user-identification information such as personal identification number (PIN) from station to station, e.g., from the station utilized by the user to enter his PIN and initiate a transaction, to the station that processes the transaction. Also, for added security, the method provides for encryption (encoding) and decryption (decoding) of data during a transaction using encryption and decryption keys produced from different (independent) PINs. The apparatus includes at least one irreversible algorithm module, a random number generator and at least one data file (e.g., disc or magnetic tape storage). The apparatus also includes a comparator or, alternatively, an encoding algorithm module and a matching decoding algorithm module.

Method and apparatus for secure message transmission for use in electronic funds transfer systems

Abstract: METHOD AND APPARATUS FOR SECURE MESSAGE TRANSMISSION FOR USE IN ELECTRONIC FUNDS TRANSFER SYSTEMS Abstract An electronic funds transfer system wherein it is required that a bank be reasonably guaranteed that the two parties to a retail transaction (i.e., a person and a retailer), agree on the transaction before the funds transfer takes place. The message including the transaction information is encryp-ted by the person using a unique encryption key (Kp) stored in a highly secure storage location in his own personal portable transaction device (XATR) and his data storage and transfer card (DSTC) and this first encrypted message is sent to the retailer who doubly encrypts the initially received encrypted message from P under his own unique encryption key (KR) and this doubly encrypted message is sent to the bank. The person also sends the transaction message to the retailer in clear, and the retailer first verifies the message and then, utilizing his own encryption key (KR), encrypts same and similarly sends it to the bank. The bank utilizing unique retailer and customer identifica-tion data sent with the message, accesses a "key" file and first extracts the retailer's key (KR) and decrypts a first portion of the message, extracts the person's key (Kp) and decrypts a second portion of the received message. The bank then compares a predetermined portion of the transaction message originating with the person with a similar portion received from the retailer and if identical, it is presumed that both the person and the retailer agreed to the trans-action and the appropriate funds transfer is made. If the messages do not agree, some sort of default procedure occurs.

System for securing postage printing transactions

Abstract: A postage meter includes printing and accounting stations interconnected through an insecure communications link. Each time the meter is tripped, a number generator at the printing station is activated to generate a number signal which is encrypted to provide an unpredictable result. The number signal is also transmitted to the accounting station. At the accounting station the postage to be printed is accounted for and the number signal is encrypted to provide a reply signal. The reply signal is transmitted to the printing station where a comparator compares it with the encryption result generated at the printing station. An equality of the encryption result and the reply signal indicates that the postage to be printed has been accounted for and the printer is activated.

IV. `Hellman presents no shortcut solutions to the DES¿

Abstract: Prof. Martin Hellman presents no shortcut solutions to the Data Encryption Standard; the time-memory tradeoff is just one of many key-message exhaustion techniques. Therefore when he says, ?DES is only marginally secure today and will be totally insecure within ten years,? he is totally wrong.

Message format for secure communication over data links

Abstract: Communication over data links using binary synchronous protocol that is to be made secure according to the Federal data encryption standard (DES) is enhanced by utilizing an encrypted message format wherein the initialization vector for the DES algorithm is at the trailing end of the message. Additional information or control words may also be strung at the trailing end of the encrypted message format without causing throughput loss while enhancing the security and flexibility of the encrypted message in both point-to-point and multipoint systems.

On the cryptocomplexity of knapsack systems

Abstract: A recent trend in cryptographic systems is to base their encryption/decryption functions on NP-complete problems, and in particular on the knapsack problem. To analyze the security of these systems, we need a complexity theory which is less worst-case oriented and which takes into account the extra conditions imposed on the problems to make them cryptographically useful. In this paper we consider the two classes of one-to-one and onto knapsack systems, analyze the complexity of recognizing them and of solving their instances, introduce a new complexity measure (median complexity), and show that this complexity is inversely proportional to the density of the knapsack system. The tradeoff result is based on a fast probabilistic knapsack solving algorithm which is applicable only to one-to-one systems, and it indicates that knapsack-based cryptographic systems in which one can both encrypt and sign messages are relatively insecure. We end the paper with new results about the security of some specific knapsack systems.

Simple and effective public-key cryptosystem

Abstract: A public encryption key (c 1 , c 2 , r) in which r is the product of two relatively prime numbers, and in which c 1 and r, as well as c 2 and r, are relatively prime numbers, is used in an encryption algorithm x=csub1 msub1 +csub2 msub2 (mod r) The decryption algorithm will be equivalent to solving simultaneous linear equations derived from the encryption algorithm Thus, both encrypting and decrypting are quite simplified while still maintaining a high degree of security

Some remarks concerning the M.I.T. public-key cryptosystem

Abstract: Let a messageM be encrypted by raisingM to a powere moduloR, whereR ande are integers which are made public. The recipient of this encrypted form ofM can decipher it by raising the cipher text to a powerd moduloR. Only the recipient knows the values of the two large primesp 1,p 2 such thatR=p 1 p 2; consequently, only he knowsd, ase is preselected such that (e, (p 1 − 1)(p 2 − 1))=1 anded ≡1 (mod (p 1 − 1)(p 2 − 1)). Recently several attacks have been made on the proposed security of this cryptosystem under iteration of the encryption procedure. In this paper we discuss methods of selecting the primesp 1,p 2 and the encryption exponente such that the possibility of breaking this cryptosystem by using an iteration procedure is minimized. Several numerical results are also presented.

Key management for encryption/decryption systems

Abstract: In a data encryption/decryption system providing for security of data communications channels, a sub-system for generating, transporting encryption/decryption keys and for introducing those keys into the system while at the same time providing a high level of security for the keys and, hence, the encryption/decryption system.

Voice encryption system

Abstract: An apparatus and method of voice encryption uses segment swapping. Features of the invention include weighting the input time-function segments by a Hamming or Hanning Window function, before converting to frequency domain segments.

Key variable generator for an encryption/decryption device

Abstract: An apparatus and method for generating a unique working key variable for controlling the operation of an encryption/decryption device during each user specified time period. The apparatus generates each working key variable by encrypting a user specified value, unique for each specified time period, under control of a fixed key variable stored in the apparatus. After the user specified value has been encrypted, the apparatus utilizes the encrypted (working) key variable to control the encryption/decryption of data during the corresponding user specified time period.

I. `DES will be totally insecure within ten years¿

Abstract: Cryptography. The very name conjures up images of secrecy and spying, with project code names like ?Magic? and ?Lucifer.? And indeed until fairly recently data encryption was a shrouded capability, used almost exclusively by military and diplomatic organizations. The computerization of information processing and transmission has changed this. In response to a growing commercial need, the National Bureau of Standards has promulgated a national Data Encryption Standard, developed by IBM. The standard, called DES, can be implemented in software or on a single LSI chip and can be used with any computer to encrypt and decrypt transmitted data. A single-chip version should sell for about $10 in quantity production. But just how good is the protection offered by DES?

Secure personal computing in an insecure network

Abstract: A method for implementing secure personal computing in a network with one or more central facilities is proposed. The method employs a public-key encryption device and hardware keys. Each user is responsible for his own security and need not rely on the security of the central facility or the communication links. A user can safely store confidential files in the central facility or transmit confidential data to other users on the network.

Multiple-destinational cryptosystem for broadcast networks

Abstract: A method of protecting communications through encryption is disclosed which is particularly useful for multiplexed communications. On the transmit side, each message is multiplied by an enciphering key corresponding to its destination, and the products are all added together to form a cryptogram. Each receiving station divides the entire cryptogram by its own deciphering key to obtain the message intended for that station.

Flexible mode DES system

Abstract: A DES (Data Encryption Standard) system utilizing an input register, control logic and output register to provide for a selection from a multiplicity of operable modes on a single chip or family of chips.

Cryptology: The Mathematics of Secure Communication

Abstract: If the model developed here for the abstract encryption/decryption channel is as general as is claimed, the discovery of asymmetric encryption techniques may be the ultimate revolution in cryptography. However, even if this should prove to be true, the impact on the practice of cryptography will continue for a very long time. For example, the mechanization of the encryption/decryption functions using computing elements, which began almost fifty years ago, has in just the past year progressed to a point where the NBS data encryption standard (DES) — a symmetric encryption scheme with a 64 bit key space [36,37] — is now offered on a single LSI chip by three manufacturers, and a two-chip MOS realization of the M.I.T. scheme with an eighty-decimal modulus has been designed. Since, in this article we were concerned more with the theory of secure communications than with the practice, no mention was made of the very significant fact that all of the asymmetric schemes which have been proposed thus far exact an extremely high price for their asymmetry — the increased amount of computation required in the encryption/decryption process cuts the channel capacity (bits per second of message information communicated) dramatically. In fact, at the moment no asymmetric scheme (to the best of the author’s knowledge) has been able to break theC 1/2 bound, whereC is the channel capacity of a symmetric channel having the same cryptosecurity and using the same basic clock or bit manipulation rate. If this difference is genuine, as we believe it to be, and not just an artifact of the asymmetric schemes which happen to have been considered, then both symmetric and asymmetric encryption/decryption schemes will be needed depending on the requirements of each application — and asymmetric techniques will not supplant symmetric techniques in general. We said earlier that the investigation of the abstract encryption/decryption channel is the most important question in contemporary applied mathematics; others have characterized it as a multimillion dollar problem [38] awaiting solution. Irrespective of the accuracy of these judgements though, we would hope that a compelling case has been presented that contemporary cryptology is an exciting and important mathematical discipline opening challenging new problems in many areas of mathematics.

Secure stand alone positive personnel identity verification system (SSA-PPIV)

Abstract: The properties of a secure stand-alone positive personnel identity verification system are detailed. The system is designed to operate without the aid of a central computing facility and the verification function is performed in the absence of security personnel. Security is primarily achieved by means of data encryption on a magnetic stripe badge. Several operational configurations are discussed. Advantages and disadvantages of this system compared to a central computer driven system are detailed.

Public key vs. conventional key encryption

Abstract: As distributed computer systems grow and their convenience attracts uses for which maintenance of privacy and security is important, the means by which encryption is integrated into these systems also becomes important. Encryption is the only practical way by which secure, private communication can be conducted while employing untrusted media to carry the transmission. The interest has spurred developments in the use of conventional encryption algorithms and there is even a federal standard algorithm for commercial use. 4 In addition, an innovative approach to encryption, called public key algorithms, has recently been proposed as a way to address many of the key distribution and other problems which are present in conventional algorithm-based approaches.

Transaction terminal systems provided with potential user authentication

Abstract: A transaction terminal system includes a user accessible terminal coupled by a message transmission link to a remote controller and incorporates a potential user authentication combination based on an encryption check and arranged so that the crictical encryption key is not resident nor is transmitted overtly to the user accessible terminal. The potential user enters into the terminal a transaction identifier and a first message from a card together with a second memorized message. The two messages are combined in the terminal to provide a key which is used to encrypt the transaction identifier. The identifier is transmitted to the controller, with and without encryption by their particular key where the identifier is encrypted by a key stored in the controller and a compari- ! son is performed between the two encrypted forms to test for validity of the input and an acceptance signal is transmitted back to the terminal. Other tests can be performed as to the validity of the transaction and the status of the terminal and the transmission can be overlayed by levels of encryption and decryption. The controller may form part of a host computer or of an intermediate node or both and authentication may be performed at the node when the host computer is off-line.

Random ciphering bounds on a class of secrecy systems and discrete message sources

Abstract: The problem of enciphering a stationary finite discrete message so that a cryptanalyst is unlikely to decrypt an intercepted cryptogram is considered. Additive-like instantaneous block (ALIB) encipherers are studied that employ a list of e^{nr} keywords of length n , called the cipher. An ALIB encipherer produces a cryptogram word of length n from a message word and a key word of the same length by combining corresponding message letters and key-word letters. Certain technical restrictions sure placed on the combining function. The decipherer uses a decoder which combines a letter from the key word used in enciphering with a letter from the cryptogram to form a letter of the decoded message. cryptanalyst also decodes letter by letter with an identical decoder; however, he uses a keyword that is not necessarily that used in enciphering. For a given message source and combiner, the design of the cipher consists in choosing the block length n , the key rate r , and the set of e^{nr} key words. These are to be chosen so that p_{w} , the probability of correct decryptment of the message word, and p( \Delta) , the probability that the per letter nonzero Hamming distance between the decrypted message and the true message is smaller than \Delta , are very small for every cryptanalyst. A set of pairs ( \Delta,r) for which there exist ciphers with key rate r such that, p_{w} and p( \Delta) can be made arbitrarily small for every cryptanalyst is determined using the concepts of random ciphering and exponential bounding.

DES Parity check system

Abstract: A system for providing on-line parity checking in data encryption/decryption systems such as DES and which is especially useful where multiple stage shifting is accomplished on a single clock input to the algorithm shift register of such a system. The parity system provides for simultaneous parity checks on a plurality of bytes where the bits of each byte are distributed through the algorithm shift register in a pseudorandom pattern.