- Broadcast encryption helps a sender to securely distribute messages to a dynamically changing set of users over an uncertainty channel. The broadcast encryption scheme needs a trusted party to distribute decoded keys. Group key agreement (GKA) protocols set up a group of members to negotiate a common encryption key via open networks so that only the group members can decrypt the texts and the contributory broadcast encryption (Con BE) can enable the sender to send message to particular member of the group but, it do not offer a fully trusted third-party to set up the system and Existing GKA protocols does not handle sender/member changes effectively. We proposed Arbitrary Topology Generalization and Identity-based Broadcast Encryption (ATIBE) scheme. The scheme holds a Private Key Generator (PKG). The PKG generates private keys from users’ identities by using a master secret key (MSK). The PKG also strengthen the public broadcast encryption key and distributes information of decryption keys to users. This scheme allows avoiding the neighbors’ communication problems, efficient encryption/decryption and only one round is requires setting up the public group. In addition to this proxy re-encryption scheme is used to improve the security level. This proposed scheme establishes secure Broadcast channels and provides a secure numerous emerging distributed computation applications.
Broadcast encryption helps a sender to securely distribute messages to a dynamically changing set of users over an uncertainty channel. The broadcast encryption scheme needs a trusted party to distribute decoded keys. Group key agreement (GKA) protocols set up a group of members to negotiate a common encryption key via open networks so that only the group members can decrypt the texts and the contributory broadcast encryption (Con BE) can enable the sender to send message to particular member of the group but, it do not offer a fully trusted third-party to set up the system and Existing GKA protocols does not handle sender/member changes effectively. We proposed Arbitrary Topology Generalization and Identity-based Broadcast Encryption (ATIBE) scheme. The scheme holds a Private Key Generator (PKG). The PKG generates private keys from users’ identities by using a master secret key (MSK). The PKG also strengthen the public broadcast encryption key and distributes information of decryption keys to users. This scheme allows avoiding the neighbors’ communication problems, efficient encryption/decryption and only one round is requires setting up the public group. In addition to this proxy re-encryption scheme is used to improve the security level. This proposed scheme establishes secure Broadcast channels and provides a secure numerous emerging distributed computation applications.
Modern collaborative and group-oriented applications typically involve communications over open networks. Given the openness of today's networks, communications among group members must be secure and, at the same time, efficient. Group key agreement (GKA) is widely employed for secure group communications in modern collaborative and group-oriented applications. This paper studies the problem of GKA in identity-based cryptosystems with an emphasis on round-efficient, sender-unrestricted, member-dynamic, and provably secure key escrow freeness. The problem is resolved by proposing a one-round dynamic asymmetric GKA protocol which allows a group of members to dynamically establish a public group encryption key, while each member has a different secret decryption key in an identity-based cryptosystem. Knowing the group encryption key, any entity can encrypt to the group members so that only the members can decrypt. We construct this protocol with a strongly unforgeable stateful identity-based batch multisignature scheme. The proposed protocol is shown to be secure under the k -bilinear Diffie-Hellman exponent assumption.
A recent primitive known as asymmetric group key agreement allows a group of users to negotiate a common encryption key which is accessible to any entities while each user holds her respective secret decryption key. This concept not only enables confidential communications among group users but also permits any outsider to send encrypted messages to the group. The existing instantiation is only secure against passive adversaries. In this paper, we first propose an authenticated asymmetric group key agreement protocol which captures the practical security properties against active attacks. Based on our protocol, we then propose a broadcast encryption system without relying on a trusted dealer to distribute the secret keys to the users. Our system has also short ciphertexts. Furthermore, the proposal is equipped with the perfect forward security property.
Identity-based Broadcast Encryption (IBBE) has the inherent key escrow problem that Private Key Generator (PKG) can fully determine the user's private key, which is an obstacle of the application of IBBE. The existing approaches to solving key escrow problem need the user to submit identity to multiple PKGs or interactions between PKG and the user in the private key extraction phase. For Point-to-Multipoint Identity-based Broadcast Encryption (P2MIBBE) that the computing capabilities of receiver are limited, these approaches are impracticable. We propose a new approach what we call Augmented Broadcaster Identity-based Broadcast Encryption (AB- IBBE). It requires neither multiple PKGs nor calculation of receiver in the private key extraction phase. We construct a universal scheme to realize AB-IBBE, such that any IND-ID-CPA secure IBBE scheme can be extended to an IND-ID-CPA secure AB-IBBE scheme.
Abstract. In identity-based public-key cryptography, an entity’s public key can be easily derived from its identity. The direct derivation of public keys in identity-based public-key cryptography eliminates the need for certificates and solves certain public key management problems in traditional public-key cryptosystems. Recently, the notion of asymmetric group key agreement was introduced, in which the group members merely negotiate a common encryption key which is accessible to any entity, but they hold respective secret decryption keys. In this paper, we first propose a security model for identity-based authenticated asymmetric group key agreement (IB-AAGKA) protocols. We then propose an IB-AAGKA protocol which is proven secure under the Bilinear Diffie-Hellman Exponent assumption. Our protocol is also efficient, and readily adaptable to provide broadcast encryption.
Nowadays, emerging technologies such as smart terminals, cloud computing, and the Internet of Things are developing rapidly. The "One-to-one" encrypted transmission method is difficult to meet the communication needs in complex network environments due to high computational costs. Broadcast encryption technology can provide data encryption protection during information sharing among multiple users. However, most of the existing schemes are based on bilinear groups, which cannot resist quantum computing attacks. And these schemes also suffer from the key escrow problem. For this reason, a novel distributed broadcast encryption scheme is proposed based on the Learning with Errors (LWE) difficulty assumption on the lattice. The scheme avoids key interaction negotiation among users by introducing a public key bulletin board. Meanwhile, the scheme solves the security problem caused by the authoritative user's complete mastery of the user's private key.
A robust group key agreement protocol (GKA) allows a set of players to establish a shared secret key, regardless of network/node failures. Current constant-round GKA protocols are either efficient and nonrobust or robust but not efficient; assuming a reliable broadcast communication medium, the standard encryption-based group key agreement protocol can be robust against arbitrary number of node faults, but the size of the messages broadcast by every player is proportional to the number of players. In contrast, nonrobust group key agreement can be achieved with each player broadcasting just constant-sized messages. We propose a novel 2-round group key agreement protocol, which tolerates up to T node failures, using O(T)-sized messages for any T. We show that the new protocol implies a fully-robust group key agreement with logarithmic-sized messages and expected round complexity close to 2, assuming random node faults. The protocol can be extended to withstand malicious insiders at small constant factor increases in bandwidth and computation. The proposed protocol is secure under the (standard) Decisional Square Diffie-Hellman assumption.