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Proceedings ArticleDOI

Encrypted key exchange: password-based protocols secure against dictionary attacks

04 May 1992-pp 72-84
TL;DR: A combination of asymmetric (public-key) and symmetric (secret- key) cryptography that allow two parties sharing a common password to exchange confidential and authenticated information over an insecure network is introduced.
Abstract: Classic cryptographic protocols based on user-chosen keys allow an attacker to mount password-guessing attacks. A combination of asymmetric (public-key) and symmetric (secret-key) cryptography that allow two parties sharing a common password to exchange confidential and authenticated information over an insecure network is introduced. In particular, a protocol relying on the counter-intuitive motion of using a secret key to encrypt a public key is presented. Such protocols are secure against active attacks, and have the property that the password is protected against offline dictionary attacks. >

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Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors present a simple technique by which a device that performs private key operations (signatures or decryptions) in networked applications and whose local private key is activated with a password or PIN can be immunized to offline dictionary attacks.
Abstract: We present a simple technique by which a device that performs private key operations (signatures or decryptions) in networked applications and whose local private key is activated with a password or PIN can be immunized to offline dictionary attacks in case the device is captured. Our techniques do not assume tamper resistance of the device but rather exploit the networked nature of the device in that the device's private key operations are performed using a simple interaction with a remote server. This server, however, is untrusted --- its compromise does not reduce the security of the device's private key unless the device is also captured --- and need not have a prior relationship with the device. We further extend this approach with support for key disabling, by which the rightful owner of a stolen device can disable the device's private key even if the attacker already knows the user's password.

42 citations

Journal ArticleDOI
TL;DR: This paper proposes a protocol that allows a client to securely use a single password across multiple servers, and also prevents phishing attacks, and is an anti-phishing password protocol that is simple, secure, efficient and user-friendly.

42 citations

Book ChapterDOI
05 Dec 2004
TL;DR: In this article, a new password-authenticated key exchange protocol, called PEKEP, which allows using both large and small prime numbers as RSA public exponent was proposed, based on number-theoretic techniques.
Abstract: We investigate efficient protocols for password-authenticated key exchange based on the RSA public-key cryptosystem. To date, most of the published protocols for password-authenticated key exchange were based on Diffie-Hellman key exchange. It seems difficult to design efficient password-authenticated key exchange protocols using RSA and other public-key cryptographic techniques. In fact, many of the proposed protocols for password-authenticated key exchange based on RSA have been shown to be insecure; the only one that remains secure is the SNAPI protocol. Unfortunately, the SNAPI protocol has to use a prime public exponent e larger than the RSA modulus n. In this paper, we present a new password-authenticated key exchange protocol, called PEKEP, which allows using both large and small prime numbers as RSA public exponent. Based on number-theoretic techniques, we show that the new protocol is secure against the e-residue attack, a special type of off-line dictionary attack against RSA-based password-authenticated key exchange protocols. We also provide a formal security analysis of PEKEP under the RSA assumption and the random oracle model. On the basis of PEKEP, we present a computationally-efficient key exchange protocol to mitigate the burden on communication entities.

42 citations

BookDOI
01 Jan 2000
TL;DR: Results on pseudorandomness of some block cipher constructions and on message authentication code constructions are covered and handy tools based on Decorrelation Theory are provided for dealing with them and how to make their proof easier is shown.
Abstract: Many previous results on the provable security of conventional cryptography have been published so far. We provide here handy tools based on Decorrelation Theory for dealing with them and we show how to make their proof easier. As an illustration we survey a few of these results and we (im)prove some by our technique. This paper covers results on pseudorandomness of some block cipher constructions and on message authentication code constructions. Decorrelation theory was introduced in [18]–[25]. Its first aim was to address provable security in the area of block ciphers in order to prove their security against differential and linear cryptanalysis. As a matter of fact, these techniques can also be used for other areas of conventional cryptography as shown in this paper. In [25] was noticed that decorrelation distances of some integral order d was linked to the advantage of the best attacks which is limited to d samples in several classes of attacks. Namely, non-adaptive attacks was characterized by decorrelation distance with the |||.|||∞ norm, chosen input attacks was characterized by decorrelation distance with the ||.||a norm, and chosen input and output attacks was characterized by decorrelation distance with the ||.||s norm. This can be used to address provable security of, say, MAC construction schemes. Due to nice properties of decorrelation distances, some previous results turn out to get simpler and more systematic. A similar systematic approach was recently addressed by Maurer [11] and it would be interesting to compare both approaches. 1 Definitions and Properties This section recalls basic facts in decorrelation theory. 1.1 Definitions and Notations First of all, for any random function F from a set M1 to a set M2 and any integer d we associate the “d-wise distribution matrix” which is denoted [F ], defined in the matrix set RM d 1×M2 by [F ]d(x1,...,xd),(y1,...,yd) = Pr[F (x1) = y1, . . . , F (xd) = yd]. JooSeok Song (Ed.): ICISC’99, LNCS 1787, pp. 1–16, 2000. c © Springer-Verlag Berlin Heidelberg 2000

42 citations

Posted Content
TL;DR: Catena is memory-hard, which can hinder massively parallel attacks on cheap memory-constrained hardware, such as recent “graphical processing units”, GPUs, and has been designed to resist cache-timing attacks.

42 citations

References
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Journal ArticleDOI
TL;DR: This paper suggests ways to solve currently open problems in cryptography, and discusses how the theories of communication and computation are beginning to provide the tools to solve cryptographic problems of long standing.
Abstract: Two kinds of contemporary developments in cryptography are examined. Widening applications of teleprocessing have given rise to a need for new types of cryptographic systems, which minimize the need for secure key distribution channels and supply the equivalent of a written signature. This paper suggests ways to solve these currently open problems. It also discusses how the theories of communication and computation are beginning to provide the tools to solve cryptographic problems of long standing.

14,980 citations


"Encrypted key exchange: password-ba..." refers background or methods in this paper

  • ...ElGamal’s algorithm is derived from the DiffieHellman exponential key exchange protocol[2]; accordingly, we will review the latter first....

    [...]

  • ...And even this risk is minimal if B performs certain checks to guard against easily-solvable choices: that β is indeed prime, that it is large enough (and hence not susceptible to precalculation of tables), that β − 1 have at least one large prime factor (to guard against Pohlig and Hellman’s algorithm[13]), and that α is a primitive root of GF (β)....

    [...]

  • ...The use given above for asymmetric encryption — simply using it to pass a key for a symmetric encryption system — is an example of what Diffie and Hellman[2] call a public key distribution system....

    [...]

  • ...It works especially well with exponential key exchange [2]....

    [...]

Journal ArticleDOI
TL;DR: An encryption method is presented with the novel property that publicly revealing an encryption key does not thereby reveal the corresponding decryption key.
Abstract: An encryption method is presented with the novel property that publicly revealing an encryption key does not thereby reveal the corresponding decryption key. This has two important consequences: (1) Couriers or other secure means are not needed to transmit keys, since a message can be enciphered using an encryption key publicly revealed by the intented recipient. Only he can decipher the message, since only he knows the corresponding decryption key. (2) A message can be “signed” using a privately held decryption key. Anyone can verify this signature using the corresponding publicly revealed encryption key. Signatures cannot be forged, and a signer cannot later deny the validity of his signature. This has obvious applications in “electronic mail” and “electronic funds transfer” systems. A message is encrypted by representing it as a number M, raising M to a publicly specified power e, and then taking the remainder when the result is divided by the publicly specified product, n, of two large secret primer numbers p and q. Decryption is similar; only a different, secret, power d is used, where e * d ≡ 1(mod (p - 1) * (q - 1)). The security of the system rests in part on the difficulty of factoring the published divisor, n.

14,659 citations


"Encrypted key exchange: password-ba..." refers methods in this paper

  • ...Section 2 describes the asymmetric cryptosystem variant and implementations using RSA[ 3 ] and ElGamal[4]....

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  • ...We will use RSA[ 3 ] to illustrate the difficulties....

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Journal ArticleDOI
Taher Elgamal1
23 Aug 1985
TL;DR: A new signature scheme is proposed, together with an implementation of the Diffie-Hellman key distribution scheme that achieves a public key cryptosystem that relies on the difficulty of computing discrete logarithms over finite fields.
Abstract: A new signature scheme is proposed, together with an implementation of the Diffie-Hellman key distribution scheme that achieves a public key cryptosystem. The security of both systems relies on the difficulty of computing discrete logarithms over finite fields.

7,514 citations

Book ChapterDOI
Taher Elgamal1
19 Aug 1984
TL;DR: In this article, a new signature scheme is proposed together with an implementation of the Diffie-Hellman key distribution scheme that achieves a public key cryptosystem and the security of both systems relies on the difficulty of computing discrete logarithms over finite fields.
Abstract: A new signature scheme is proposed together with an implementation of the Diffie - Hellman key distribution scheme that achieves a public key cryptosystem. The security of both systems relies on the difficulty of computing discrete logarithms over finite fields.

2,351 citations

Book
01 Jan 1982
TL;DR: The goal of this book is to introduce the mathematical principles of data security and to show how these principles apply to operating systems, database systems, and computer networks.
Abstract: From the Preface (See Front Matter for full Preface) Electronic computers have evolved from exiguous experimental enterprises in the 1940s to prolific practical data processing systems in the 1980s. As we have come to rely on these systems to process and store data, we have also come to wonder about their ability to protect valuable data. Data security is the science and study of methods of protecting data in computer and communication systems from unauthorized disclosure and modification. The goal of this book is to introduce the mathematical principles of data security and to show how these principles apply to operating systems, database systems, and computer networks. The book is for students and professionals seeking an introduction to these principles. There are many references for those who would like to study specific topics further. Data security has evolved rapidly since 1975. We have seen exciting developments in cryptography: public-key encryption, digital signatures, the Data Encryption Standard (DES), key safeguarding schemes, and key distribution protocols. We have developed techniques for verifying that programs do not leak confidential data, or transmit classified data to users with lower security clearances. We have found new controls for protecting data in statistical databases--and new methods of attacking these databases. We have come to a better understanding of the theoretical and practical limitations to security.

1,937 citations


"Encrypted key exchange: password-ba..." refers background in this paper

  • ...Can such a random odd number less than a known n be distinguished from a valid public key e? Assume that p and q are chosen to be of the form 2p′ + 1 and 2q′ + 1, where p′ and q′ are primes, a choice that is recommended for other reasons [9]....

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