A computer-implemented method for protecting sensitive data via data re-encryption is provided. Encrypted data is maintained. A data query is received from a user associated with a public key and a secret key. Results of the query are computed by identifying at least a portion of the encrypted data and by adding plaintext for the identified portion of the encrypted data as the results. A re-encryption key is generated for the results using the public key of the user and the results are re-encrypted using the re-encryption key. The re-encrypted results are then transmitted to the user.

Managing access to digital content within a particular domain, including: receiving the digital content at a first client device; decrypting the received digital content at the first client device using a first key; transcoding the digital content to another format; re-encrypting the transcoded content using a second key, wherein the second key is obtained by one of: (1) directly from a server; or (2) indirectly by deriving it locally based on information received from the server; and transmitting the re-encrypted content to a second client device, wherein the second client device obtains the second key and decrypts the re-encrypted content at the second client device.

Techniques and architectures may be used to provide an environment where a data owner storing private encrypted data in a cloud and a data evaluator may engage in a secure function evaluation on at least a portion of the data. Neither of these involved parties is able to learn anything beyond what the parties already know and what is revealed by the function, even if the parties are actively malicious. Such an environment may be useful for business transactions, research collaborations, or mutually beneficial computations on aggregated private data.

Systems and methods to securely send or write data to a cloud storage or server. In one embodiment, a method includes: establishing a connection to a client using a client-side transport protocol; receiving, over the connection, data from the first client; decrypting, using a client session key, the received data to provide first decrypted data; encrypting the first decrypted data using a stored payload key (that is associated with the client) to provide first encrypted data; encrypting, using a cloud session key, the first encrypted data using a remote-side transport protocol to provide second encrypted data; and sending the second encrypted data to the cloud storage or server.

Techniques for employing a secure enclave to enhance the security of a system that makes use of a remote server that proxies cryptographic keys. In one technique, a proxy server receives a request for a cryptographic operation that is initiated by a client device. The request includes a key name of a cryptographic key and a (e.g., authentication) code. In response, the proxy server sends the code and the request to a secure enclave that is associated with a cryptographic device that stores the cryptographic key. The secure enclave validates the code based on a local key and sends, to the cryptographic device, (1) data associated with the secure enclave and (2) the cryptographic request. The proxy server receives result data that was generated by the cryptographic device that performs the cryptographic operation. The proxy server sends the result data to the client device.

A device and method are provided for establishing a session key between two entities of a communication network that may be highly heterogeneous in terms of resources. The method, based on the Diffie-Hellman (DH) algorithm, provides for the delegation to assistant nodes of the network of the cryptographic operations required for the computations of the DH public value and of the DH session key for the node which is constrained in terms of resources.

This application discloses quantum key distribution methods and devices, and storage media. In an implementation, an i.sup.th node generates, based on a determined first quantum key corresponding to the i.sup.th node on a target routing path and a determined second quantum key corresponding to the i.sup.th node on the target routing path, a third quantum key corresponding to the i.sup.th node on the target routing path, and sends the third quantum key corresponding to the i.sup.th node on the target routing path to a destination node on the target routing path, or encrypts a received first ciphertext by using the third quantum key corresponding to the i.sup.th node on the target routing path, and sends an obtained second ciphertext corresponding to the i.sup.th node to an (i+1).sup.th node on the target routing path.

An apparatus in one embodiment comprises a processing platform having at least one processing device. The processing platform implements a trusted bridge configured for at least temporary coupling between one or more data sources and a smart contract program of a blockchain. The trusted bridge comprises a secure enclave component and a relay component. Data obtained from a given one of the data sources via the relay component of the trusted bridge is authenticated in the secure enclave component of the trusted bridge. Information based at least in part on the data authenticated in the secure enclave component of the trusted bridge is provided to the smart contract program of the blockchain via the relay component of the trusted bridge. The secure enclave component illustratively receives a request for authenticated data from the blockchain smart contract program via the relay component, and responds to the request via the relay component.

A method is provided for delegating behavior of a smart contract associated with a blockchain to code that is not part of the blockchain. A system directs execution by a virtual machine of the smart contract. During execution of the smart contract, the smart contract sends to a cryptlet container service, via a cryptodelegate, a request to delegate a behavior to a cryptlet that executes on an attested host. During execution the cryptlet container service identifies a host for executing code of the cryptlet in an appropriate cryptlet container. The cryptlet container service directs the identified host to execute the code of the cryptlet to perform the delegated behavior. After the delegated behavior is performed, the cryptlet container service receives from the cryptlet a response to the requested behavior. The cryptlet container service sends the response to the smart contract on the blockchain that is verified by the cryptodelegate.

An e-mail firewall applies policies to e-mail messages between a first site and second sites in accordance with administrator selectable policies. The firewall includes a simple mail transfer protocol relay for causing the e-mail messages to be transmitted between the first site and selected ones of the second sites. Policy managers enforce-administrator selectable policies relative to one or more of encryption and decryption, signature, source/destination, content and viruses.