Methods and systems are provided for authenticating a message μ, at a user computer of a group signature scheme, to a verifier computer. The method includes, at the user computer, storing a user id m for the user computer and a user signing key which comprises a signature on the user id m under a secret key of a selectively-secure signature scheme. The user id m is an element of a predetermined subring, isomorphic to .sub.q[x]/(g(x)), of a ring R=.sub.q[x]/(f(x)), where f(x) and g(x) are polynomials of degree deg(f) and deg(g) respectively such that deg(f)>deg(g)>1. The method includes, at the user computer, generating a first cryptographic proof Π.sub.1 comprising a zero-knowledge proof of knowledge of the user signing key and including the message μ in this proof of knowledge. The user computer sends the message μ and a group signature, comprising the first proof Π.sub.1, to the verifier computer.

The disclosed embodiments provide a system that provides wireless service groups. During operation, a wireless device's advertising mechanism advertises a service group over Wi-Fi, wherein the service group comprises at least the wireless device and wherein the service group's security requirements regulate multicast protection within the service group. In response to receiving a request from a second device to be admitted into the service group, the wireless device's security mechanism admits the second device into the service group and sends the service group's security requirements to the second device, thereby enabling the second device to initialize multicast protection in accordance with the service group's security requirements.

Cryptographically secure data communications between layered groups of devices in a wireless cooperative broadcast network encrypts datagrams twice prior to transmission by a source device, first using an inner layer key that is shared by a first group of devices, and second using an outer layer key that is shared by a second group of devices; the devices of the first group being members of the second group. Received datagrams are recovered by first decrypting with the outer layer key and second decrypting with the inner layer key.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, to a node, a request for a security key for sidelink connectionless groupcast communication that is performed without a radio resource control connection between UEs. The request may indicate a distance from the UE for using the security key. The UE may receive, from the node, information that indicates the security key. Numerous other aspects are described.

This disclosure relates to systems and methods for managing connected devices and associated network connections. In certain embodiments, trust, privacy, safety, and/or security of information communicated between connected devices may be established in part through use of security associations and/or shared group tokens. In some embodiments, these security associations may be used to form an explicit private network associated with the user. A user may add and/or manage devices included in the explicit private network through management of various security associations associated with the network's constituent devices.

Secure data transfers between communication nodes is performed using a group encryption key supplied by a remote management system. A first node transmits a request for secure communications with a second node to the remote management system using a control channel. The remote management system generates and encrypts a group encryption key usable by the first and second nodes and forwards the encrypted group encryption key to the first and second nodes using one or more control channels. The first and second communication nodes decrypt the group encryption key and use it to encrypt data transmitted between the nodes using a data transport network. In some implementations the securely communicating nodes may use encryption keys and/or techniques that prevent the remote management system from eavesdropping on the nodes' communications.

Disclosed are systems and methods that facilitate encryption of email messages that are transported between mail servers. In some cases, email messages may be relayed through relay mail servers as well. An email message can be encrypted using a public key that corresponds to an organization associated with the recipient rather than a public key associated with the particular recipient. The email message can then be decrypted by the recipient mail server and deposited into a mailbox of the recipient.

Methods of half-duplex communication systems or full-duplex communication systems are provided. The half-duplex communication system includes n number user units-including a transmitting unit of transmitting units, wherein the transmitting unit including a channel estimation module, an identity update module and a modulation module; a receiving unit of receiving units including a demodulation module, a post-processing module and a reconciliation and verification module; a memory unit for storing prime identities, data to be transmitted and shared secret key; a control unit; an antenna connected to each of the transmitting units and each of the receiving units; and the methods are used for realizing a generation of shared secret keys, and an integrated identity verification and a data transmission using the half-duplex communication systems and the full-duplex communication systems.

Method, server, and communication device for updating identity-based cryptographic private keys of compromised communication devices. One method includes receiving, at a server, a security status indicating that the security of a first communication device has been compromised. The first communication device is associated with a user and includes a first identity-based cryptographic private key and a first user identifier. The method also includes, responsive to receiving the security status, determining, with the server, a second user identifier based on the first user identifier. The method further includes determining, with the server, a second identity-based cryptographic private key based on the second user identifier. The method also includes distributing, via the server, the second identity-based cryptographic private key to a second communication device. The second communication device is associated with the user.

Method and server for issuing a cryptographic key. One method includes distributing a first group key to a first communication device and a second communication device. The method also includes distributing a security request to the first communication device. The method further includes receiving a security status from the first communication device responsive to transmitting the security request. The method also includes determining when security of the first communication device is compromised based on the security status. The method further includes distributing, via a server, the cryptographic key to the first communication device when the security of the first communication device is not compromised. The method also includes distributing, via the server, a second group key to the second communication device when the security of the first communication device is compromised and the first communication device cannot be fixed or deactivated.