Showing papers on "Cryptography published in 1981"

On the security of public key protocols

Abstract: Recently the use of public key encryption to provide secure network communication has received considerable attention. Such public key systems are usually effective against passive eavesdroppers, who merely tap the lines and try to decipher the message. It has been pointed out, however, that an improperly designed protocol could be vulnerable to an active saboteur, one who may impersonate another user or alter the message being transmitted. Several models are formulated in which the security of protocols can be discussed precisely. Algorithms and characterizations that can be used to determine protocol security in these models are given.

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.

Cryptography, a primer

Abstract: From the Publisher: The first systematic development of the principles and technology underlying the disguising of text and computer data. Formulates the principles underlying encipherment, analyzes a number of basic systems including the ``Enigma machine,'' and treats applications to data processing: public key systems, electronic signatures, communication and file security.

Cryptographic Authentication of Time-Invariant Quantities

Abstract: With any strong cryptographic algorithm, such as the data encryption standard (DES), it is possible to devise protocols for authentication. One technique, which allows arbitrary, time-invariant quantities (such as encrypted keys and passwords) to be authenticated, is based upon a secret cryptographic (master) key residing in a host processor. Each quantity to be authenticated has a corresponding precomputed test pattern. At any later time, the test pattern can be used together with the quantity to be authenticated to generate a nonsecret verification pattern. The verification pattern can in turn be used as the basis for accepting or rejecting the quantity to be authenticated.

Cryptographic application for interbank verification

Abstract: In a data communication network which includes terminals interconnected via a central switch, a process for verifying the identity of a terminal user who is provided with secret data associated with his identity. In carrying out the verification process, the secret data is first encrypted at the terminal under a transfer-in key for transmission to an associated data processing system. When it is determined that the terminal user maintains an account at the associated data processing system, a first translate operation is performed to translate the data from encryption under the transfer-in key to encryption under an authentication key, both of which keys are protected under other keys which are different from each other, thereby providing an authentication parameter which may be used to verify the identity of the terminal user. When it is determined that the terminal user does not maintain an account at the associated data processing system, a second translate operation is performed to translate the data from encryption under the transfer-in key to encryption under a transfer-out key for transmission to the next associated host system, the switch or a remote host system. At each such node, except the switch, a determination is made as to whether a verification process can be performed otherwise, the encrypted data is translated for transmission to the next or a remote node of the network for such verification.

An algorithm for modular exponentiation

Abstract: The best known algorithm for modular exponentiation Me mod t for arbitrary M, e and t is of O(n3) where n is the number of bits in the largest of M, e and t. This paper presents an O(n2) algorithm for the problem where Me mod t is required for many values of M and e with constant t some preprocessing is done on t, and the results are applied repeatedly to different values of M and e. The main algorithm involves on-line arithmetic in a redundant. number system. An immediate application is in encoding/decoding of messages in an RSA-based public-key cryptosystem.

Security Requirements and Protocols for a Broadcast Scenario

Abstract: Previous work (e.g., [1], [2]) has characterized communication security requirements in connection-oriented (virtual circuit) environments supporting applications such as interactive communication and file transfer. This work has developed protocols to achieve these requirements using conventional ciphers (CC's) such as the NBS data encryption standard (DES) [3]. More recently, several authors [4]-[6] have analyzed key distribution protocols for such environments based on CC's and on public-key ciphers (PKC's) such as the RSA algorithm [7], noting similarities in form, function, and vulnerability. Advances in satellite and packet radio technology [8], [9] and the development of high-speed, local area networks [10] have stimulated interest in broadcast protocols for various applications. This article examines security requirements for a simple broadcast scenario characteristic of some of these applications and develops protocols for achieving these requirements. Two sets of protocols, one based on CC's and the other based on PKC's, are developed and analyzed in terms of functionality and performance.

Integrating the Data Encryption Standard into Computer Networks

Abstract: The NBS Data Encryption Standard may be integrated into computer networks to protect personal (nonshared) files, to communicate securely both on- and off-line with local and remote users, to protect against key substitution, to authenticate system users, to authenticate data, and to provide digital signatures using a nonpublic key encryption algorithm. Key notarization facilities give users the capability of exercising a set of commands for key management as well as for data encryption functions. The facilities perform notarization which, upon encryption, seals a key or password with the identities of the transmitter and intended receiver. Thus, in order to decrypt a message, the receiver must authenticate himself and supply the correct identity of the transmitter. This feature eliminates the threat of key substitution which must be protected against to attain a high level of security.

Error-Correcting Codes and Cryptography

Abstract: This paper is intended to serve as an introduction to the exciting developments in secret codes that have taken place in the last ten years. David Kahn’s interesting book The Codebreakers appeared in 1967 [29], which unfortunately was just before IBM described its Lucifer encryption scheme [11], [20], [51] and triggered the developments that I am going to describe.

Encryption and Authentication in On-Board Processing Satellite Communication Systems

Abstract: Encryption is an efficient method for information protection in communication links which are subject to wiretapping. In this paper we discuss the application of encryption to satellite communication systems in which the satellite has on-board processing capability. The on-board processor can be used in the key distribution process. Two examples of such processes are described. The first requires the storage in the satellite of one key for each user of the communication system. These are used together with a conventional encryption algorithm (DES, for example) to distribute communication keys to the users. The communication keys are then used to encrypt and decrypt information. The other key distribution process utilizes a trap-door one-way function, whose inverse is implemented in the satellite. The need for storage space in the satellite is smaller than that with the first method.

Digital signature schemes for computer communication networks

Abstract: This paper introduces four new digital signature schemes for computer communication networks. These involve one or more arbitrators who validate and authenticate messages and signatures without having access to the actual contents of the messages.

Report of the public cryptography study group

Abstract: In the spring of 1980, the American Council on Education (ACE) formed and commissioned the Public Cryptography Study Group (PCSG) to examine the question of prepublication review of papers in cryptology. This question had been raised by the National Security Agency (NSA) in its concern for protecting the national security. ACM President Daniel McCracken appointed David Brandin as ACM's representative to the PCSG. (In PCSG jargon, Brandin was our \"'nominee\".) '

Some cryptographic principles of authentication in electronic funds transfer systems

Abstract: One essential requirement of an Electronic Funds Transfer (EFT) system is that institutions must be able to join together in a common EFT network such that a member of one institution can initiate transactions at entry points in the domain of another institution. The use of such a network is defined as interchange. Cryptographic implementations are developed for such a network in such a way as to keep personal verification and message authentication processes at different institutions completely separate. This is accomplished through the combined use of user-remembered personal identification numbers (PINs), secret system keys, and intelligent secure (bank) cards on which are recorded secret personal cryptographic keys.

The case against restraints on non-governmental research in cryptography

Abstract: A device for cooling liquid metals in atomic nuclear reactors or an installation for simulating the conditions in such reactors. The liquid metal is conducted over the exterior surfaces of heat energy conducting pipes and the preferably gaseous cooling medium is conducted through said pipes, the two fluids being thus separately conducted. The pipes are mounted between a pair of parallel end plates and are open at both ends and are surrounded by a cylindrical member.

Required Cryptographic Authentication Criteria for Electronic Funds Transfer Systems

Abstract: A set of required security criteria is developed which assures that the personal verification processes at different institutions in an interchange environment are isolated from one another. It is assumed that only information stored on the bank card and information remembered by a systerm user are employed for personal verification. Under that assumption, it is shown that only through the use of a secret quantity (a personal cryptographic key) stored on the bank card will the set of required criteria be satisfied. With a personal key, the same degree of isolation can be achieved for authentication of transaction request messages sent from the entry point to the issuer. However, authentication of transaction response messages sent from the issuer to the entry point requires a system key unknoun to the user.

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.

Cryptographic sealing for information secrecy and authentication

Abstract: The problem of computer security can be considered to consist of four distinct components: secrecy (ensuring that information is only disclosed to authorized users), authentication (ensuring that information is not forged), integrity (ensuring that information is not destroyed), and availability (ensuring that access to information can not be maliciously interrupted).The paper describes a new protection mechanism called cryptographic sealing that provides primitives for secrecy and authentication. The mechanism is enforced with a synthesis of classical cryptography, public-key cryptography, and a threshold scheme.

Future Applications of Cryptography

Abstract: Cryptography is no longer the province of a specialized elite of mathematicians and military operatives. Its potential cost-effective applications to modern computer/communications systems appear to be many and varied. In spite of disappointing sales of cryptographic equipment, the market for these devices is expected to rapidly expand over the next several years.

Security or Censorship? The Cryptography Controversy

Abstract: 12. Nicholas Bethell, The Palestine Triangle: The Struggle Between the British, the Jews and the Arabs. 1935-1948 (London, 1979), passim; Hurewitz, pp. 295-329. 13. Curtis et al, pp. 52-62, 70, 131. 14. Nadav Safran, Israel: the Embattled Ally (Cambridge, Mass., 1978), pp. 67-82, 385. 15. ibid., pp. 258-61, 266-71; Bard E. O'Neill, Armed Struggle in Palestine: a Political-Military Analysis (Boulder, Colo., 1978), pp. 43-50, 107-23; Curtis et al, pp. 114-16, 139. 16. The war stirred considerable controversy within Israel, especially in the Israeli Defence Forces. For a useful account and analysis see Chaim Herzog, The War of Atonement: October 1973 (Boston, 1975). 17. George Lenczowski, The Middle East in World Affairs. 4th ed. (Ithaca, N.Y., 1980), pp. 568-71. 18. O'Neill, PP. 215-17. 19. Lenczowski, pp. 606-10; Safran, p. 567. 20. Colin Legum, ed.. Middle East Contemporary Survey. Vol. 2. 1977-78 (New York, 1979), pp. 213-15, 227-30, 232-33. 21. See "A Sudden Vision of Peace", Time, 25 Sept. 1978, and "A Glimpse of Peace", Newsweek, 26 Mar. 1979; New York Times, 5 June 1980; Economist, 23 Aug. 1980; Washington Post, 5 Mar. 1981. 22. Adeed Dawisha, "Saudi Arabia's Search for Security", Adelphi Papers, no. 158 (1980); Washington Post. 6 Feb. 1980; Newsweek, 3 Mar., 4 Aug. 1980; Time, 16 Mar. 1981. 23. Interviews with Yasser Arafat, Time, 9 Apr. 1979, International Herald Tribune, 31 July, 6 Aug. 1980; see also, Time, 14 Apr. 1980; Newsweek, 8 Sept. 1980; Guardian Weekly, 16 Mar. 1980; Economist, 21 June, 9 Aug. 1980. 24. New York Times, 1 June 1980, 5 Feb. 1981; Newsweek, 11 Aug. 1980, 23 Mar. 1981; Economist, 28 Feb. 1981; Time, 16 Mar. 1981.

A Critique of Some Public-Key Cryptosystems

Abstract: Several of the public-key cryptosystems that received considerable publicity are examined. The uses, implementation, and potential cryptoanalytic attacks are discussed. Since most of the suggested systems depend on the manipulation of large numbers, special multi precision computer programs have been developed to demonstrate system implementation and cryptoanalytic attacks. Examples of the use and timing of these programs are included.

The Discrete Logarithm Public Cryptographic System

Abstract: The report is a study and primer of the discrete logarithm public key cryptographic system. Implementation and strengths and weaknesses are discussed.