T. Hwang. Cryptosystem for group oriented cryptography. In I. B. Damgard, editor, Advances in Cryptology|EUROCRYPT 90, volume 473 of Lecture Notes in Computer Science, pages 352-360, Aarhus, Denmark, May 1990. Springer-Verlag, 1991.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....a message to a group of people. The idea is that sometimes it is good to enforce cooperation among a group so that recipients cannot deny receiving the message and one recipient cannot prevent another recipient from getting the message. Soon secret sharing schemes proved to be a useful tool, [20, 14], which led to the term threshold cryptography since the solutions are base on threshold secret sharing scheme. Desmedt has written two surveys on threshold cryptography, 15, 13] The term threshold cryptography covers all distributed cryptographic operations, where the distribution is through a ....

T. Hwang. Cryptosystem for group oriented cryptography. In Notes in Computer Science, pages 352--360, 1990.

....in order to generate shares of the key so that partial cryptograms can be combined into a cryptogram for the correct message, cf. 1] Threshold encryption has not received a great deal of attention, perhaps because of its limited practical significance. 0. 44.2 Threshold decryption Hwang [49] proposes a cryptosystem for group decryption based on the discrete logarithm problem. In his system it is assumed that the sender knows the participants of the group. The sender encrypts the message using a predetermined (either private or public key) cryptosystem with a secret key known to the ....

T. Hwang. Cryptosystem for group oriented Cryptography. Proc. Eurocrypt'90. LNCS Vol. 473, Springer-Verlag, Berlin, 1990, pp. 353-360.

....group is a group with known members. Each member of the intended group is either an individual or a group with anonymous membership (from cryptographic point of view, groups with anonymous membership act as individuals) There has not been much research on group oriented cryptography. Hwang [7] proposed a shared decryption system in which the sender knows the set of receivers. The Hwang system utilises the Diffie Hellman [2] key distribution scheme, and concatenates the Shamir [11] secret sharing scheme with a predetermined cryptographic system. Franklin and Haber [4] also discussed ....

T. Hwang, "Cryptosystem for Group Oriented Cryptography," in Advances in Cryptology - Proceedings of EUROCRYPT '90 (I. Damgard, ed.), vol. 473 of Lecture Notes in Computer Science, pp. 352--360, Springer-Verlag, 1991.

....clerks. Desmedt and Frankel [4] showed an efficient (k; n) threshold ElGamal type public key cryptosystem such that (1) k out of n members must cooperate to decrypt a ciphertext. 2) Any k Gamma 1 dishonest members cannot decrypt any ciphertexts. This system requires a trusted center. Hwang [5] and then Pedersen [6] showed that the trusted center can be eliminated. In the system of Hwang 2 [5] however, the size of the group public key is much larger than that of Desmedt and Frankel [4] because each member publicizes his own public key. In the system of Pedersen [6] the public key is ....

....such that (1) k out of n members must cooperate to decrypt a ciphertext. 2) Any k Gamma 1 dishonest members cannot decrypt any ciphertexts. This system requires a trusted center. Hwang [5] and then Pedersen [6] showed that the trusted center can be eliminated. In the system of Hwang 2 [5], however, the size of the group public key is much larger than that of Desmedt and Frankel [4] because each member publicizes his own public key. In the system of Pedersen [6] the public key is as small as that of Desmedt and Frankel [4] Pedersen s system makes use of a noninteractive ....

T. Hwang, "Cryptosystem for group oriented cryptography ", In Proc. of Eurocrypt'90, Lecture Notes in Computer Science, LNCS 473, Springer Verlag, pp.352--360, 1991.

....first threshold cryptosystems [42] were independently developed by CroftHarris [35] Boyd [18] and Desmedt [41] They were, as most pioneering systems, either imperfect, having a hidden security bug, or too restrictive, or impractical. Since then, new threshold cryptosystems have been developed [43, 44, 53, 63, 71, 74] satisfying almost all of the ideal system s properties defined in one of the previous sections. In some threshold cryptosystems it is possible to generate a threshold group signature (see e.g. 44] Threshold signatures are somewhat related to multisignatures [120] and simple group signatures ....

....have to be chosen again. The public and the private key are then recomputed. Otherwise, the new member would know other members public keys before choosing his her own key, which is a contradiction to the purpose of key agreement. 1.5. 6 Group oriented cryptosystem with authorized members Hwang [71] presented a discrete logarithm based decryption scheme in which the sender knows the identities of the receiving shareholders. Hwang developed the group cryptosystem starting from the Diffie Hellman key distribution scheme [45] and Shamir s secret sharing scheme [143] As an encryption algorithm, ....

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Hwang, T., Cryptosystem for Group Oriented Cryptography, Proceedings of EUROCRYPT 90, Springer Verlag, 352--360, 1991

....However, a non interactive and practical solution to this problem was left as an open problem. 1 Support for this project was provided in part by the Australian Research Council under the reference number A49530480 and the ATERB grant. A. Related work At the Eurocrypt 90 conference, Hwang [6] proposed a solution to the above problem. However, his scheme is not a group oriented threshold cryptosystem. The Hwang system utilizes the Diffie Hellman [4] key distribution scheme, and concatenates Shamir s [9] secret sharing scheme with a predetermined cryptographic system, which can be ....

T. Hwang. Cryptosystem for Group Oriented Cryptography. In Advances in Cryptology - Proceedings of EUROCRYPT '90, Ed. I.B. Damgard, Lecture Notes in Computer Science, Vol. 473, pages 353--360. Springer-Verlag, 1990.

....operations is replaced by a group of participants who collaborate to perform the same cryptographic operation. Group oriented cryptography is particularly useful in the context of distributed computer systems where frequently an action, for example signing a message [3] or encrypting a cryptogram [8], requires the collaboration of a number of participants. There are two main approaches in modeling and assessment of group oriented systems: unconditional security where there is no limitation on the computational power of the enemy, and computational security, where security relies of excessive ....

T. Hwang. Cryptosystem for group oriented cryptography. In Advances in Cryptology - EUROCRYPT'90, I. Damgard (ED), Lecture Notes in Computer Science, Vol.473, pages 353--360. Springer Verlag, May 1990.

....main motivating factor is the increasing popularity of various types of groupware applications and the need of doing it securely. Since key distribution is the cornerstone of secure group communication, it has naturally received a lot of attention. See, for example: 2] 3] 4] 5] 6] 7] [8], 9] Unfortunately some of the results are of only theoretical interest, while the security of some others remains unproven. In this paper we consider a class of protocols that we call natural extensions of the 2 party Diffie Hellman key exchange. We define a generic protocol of this class ....

Tzonelih Hwang. Cryptosystem for group oriented cryptography. In I.B. Damgard, editor, Advances in Cryptology -- EUROCRYPT '90, number 473 in Lecture Notes in Computer Science, pages 352--360. Springer-Verlag, Berlin Germany, May 1991.

....scheme based on the RSA cryptosystem, but in some cases their scheme is time consuming. A good review of literature in this area can be found in [4] Note that for the majority of cryptosystems published so far, senders do not know whether the recipient is an individual or a group. Hwang [10] presented a cryptosystem in which the sender knows the participants. Unfortunately, the proposed scheme does not work well with threshold systems. As mentioned in [10] both conventional and public key cryptosystems are applicable in this scheme and therefore one can claim that a share decryption ....

....for the majority of cryptosystems published so far, senders do not know whether the recipient is an individual or a group. Hwang [10] presented a cryptosystem in which the sender knows the participants. Unfortunately, the proposed scheme does not work well with threshold systems. As mentioned in [10], both conventional and public key cryptosystems are applicable in this scheme and therefore one can claim that a share decryption based on conventional cryptosystems (like the DES) is possible (while no such scheme has been proposed so far) 3 Shortcomings of existing threshold cryptosystems In ....

T. Hwang. Cryptosystem for group oriented cryptography. In Advances in Cryptology - EUROCRYPT'90, I. Damgard (ED), Lecture Notes in Computer Science, Vol.473, pages 353--360. Springer Verlag, May 1990.

....for threshold signatures) A threshold decryption scheme based on the El Gamal cryptosystem [11] was presented in [8] 5.4 Recent results Since the authors presented the idea of threshold cryptography [8] many variant schemes have been presented. A threshold decryption scheme was developed in [17]. Its main advantage was that a trusted key distribution center is not needed, however the scheme is impractical when l is large because the ciperhtext grows in function of l. A threshold multisignature and threshold decryption scheme was presented in [19] This scheme is based on RSA. This ....

Hwang, T. Cryptosystems for group oriented cryptography. In Advances in Cryptology, Proc. of Eurocrypt '90 (Lecture Notes in Computer Science 473) (1991), I. Damgard, Ed., Springer-Verlag, pp. 352--360. Aarhus, Denmark, May 21--24.

....the participants update their shares the signatures can be easily modified to certify the new shares. 2 Summary of previous results Exponentiation in GF (q) q is a prime) is often used as a one way function. Diffie and Hellman [8] used it to design their public key distribution system. Hwang [9] made use of the discrete logarithm problem to design a cryptosystem for group oriented cryptography. Lin and Harn [10] used the RSA exponentiation to design a secret sharing scheme which detects cheating. Some other applications of exponentiation in secret sharing schemes are related to threshold ....

T. Hwang. Cryptosystem for group oriented cryptography. In Advances in Cryptology - EUROCRYPT'90, Lecture Notes in Computer Science, Vol.473, pages 353--360. Springer Verlag, May 1990.

....the help of trusted clerks) Later Desmedt and Frankel [6] proposed a solution to the problem. A good review of literature in this area can be found in [7] Note that for the majority of cryptosystems published so far, senders do not know whether the recipient is an individual or a group. Hwang [10] proposed a cryptosystem in which the sender knows the participants. Unfortunately, his scheme does not work well with the concept of group oriented threshold cryptography. As mentioned in [10] both conventional and public key cryptosystems are applicable in this scheme and therefore one can ....

....published so far, senders do not know whether the recipient is an individual or a group. Hwang [10] proposed a cryptosystem in which the sender knows the participants. Unfortunately, his scheme does not work well with the concept of group oriented threshold cryptography. As mentioned in [10], both conventional and public key cryptosystems are applicable in this scheme and therefore one can claim that a threshold decryption based on conventional cryptosystems (like the DES) is possible, while no such scheme has been proposed so far. 3. Shortcomings of existing threshold cryptosystems ....

T. Hwang. Cryptosystem for Group Oriented Cryptography. In Advances in Cryptology - Proceedings of EUROCRYPT '90, Ed. I.B. Damgard, Lecture Notes in Computer Science, Vol. 473, pages 353--360. Springer-Verlag, 1990.

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T. Hwang. Cryptosystem for group oriented cryptography. In I. B. Damgard, editor, Advances in Cryptology|EUROCRYPT 90, volume 473 of Lecture Notes in Computer Science, pages 352-360, Aarhus, Denmark, May 1990. Springer-Verlag, 1991.

No context found.

Hwang T (1990) Cryptosystem for group oriented cryptography. In: Proc. EUROCRYPT '90. LNCS, vol 473. Springer, Berlin Heidelberg New York, pp 352--360

No context found.

T. Hwang. Cryptosystem for group oriented cryptography. In EUROCRYPT '90 (LNCS 473), pages 352--360, 1990.

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