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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Patent•
23 Apr 2003TL;DR: In this paper, a method of presenting password information to a user, the method comprising: receiving a password, determining the number of unique character sets utilized in the password, and displaying the number that are contained within the password.
Abstract: A method of presenting password information to a user, the method comprising: receiving a password; determining the number of unique character sets utilized in the password; and displaying the number of unique character sets that are contained within the password.
57 citations
TL;DR: It is found that the STPKE protocol is still vulnerable to undetectable on-line password guessing attacks by using formal description, BPR model, and a countermeasure is suggested to resist these attacks.
57 citations
04 Dec 2005
TL;DR: In this paper, the authors present the Threshold Password-based Authenticated Key Exchange (GTPAKE) system, which uses a pair of public/private keys and, unlike traditional threshold-based constructions, shares only the private key among the servers.
Abstract: This paper brings the password-based authenticated key exchange (PAKE) problem closer to practice. It takes into account the presence of firewalls when clients communicate with authentication servers. An authentication server can indeed be seen as two distinct entities, namely a gateway (which is the direct interlocutor of the client) and a back-end server (which is the only one able to check the identity of the client). The goal in this setting is to achieve both transparency and security for the client. And to achieve these goals, the most appropriate choices seem to be to keep the client’s password private even from the back-end server and use threshold-based cryptography. In this paper, we present the Threshold Password-based Authenticated Key Exchange (GTPAKE) system: GTPAKE uses a pair of public/private keys and, unlike traditional threshold-based constructions, shares only the private key among the servers. The system does no require any certification except during the registration and update of clients’ passwords since clients do not use the public-key to authenticate to the gateway. Clients only need to have their password in hand. In addition to client security, this paper also presents highly-desirable security properties such as server password protection against dishonest gateways and key privacy against curious authentication servers.
56 citations
TL;DR: A round- and computation-efficient three-party authenticated key exchange protocol is proposed which fulfils all of the above mentioned requirements.
55 citations
Cites background from "Encrypted key exchange: password-ba..."
...Encryption key exchange between two communication parties (2PAKE) was first proposed to securely generate a session key with a weak shared password against dictionary attacks (Bellovin and Merrit, 1992)....
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References
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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....
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...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)....
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...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....
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...It works especially well with exponential key exchange [2]....
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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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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
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 1982TL;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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