Method and system for secure information distribution based on group shared key

A system for secure information distribution, comprising:

• a server for generating a key pair which includes a public key and a private key and is required by a public key cryptographic algorithm, generating a group shared key and a key deriving parameter corresponding to the group shared key, wherein the server is configured to encrypt a package of sensitive content by use of the group shared key to obtain a package of encrypted information;
• and
• a plurality of terminals, configured to receive the encrypted information broadcasted by the server through an open channel, decrypt the encrypted information by use of the group shared key to obtain the sensitive content,
• wherein, each of the plurality of terminals is configured to encrypt its private identifier which is global unique by use of the public key, to generate a ciphertext of the private identifier,
• wherein, the server is configured to generate the key deriving parameter by executing following steps:
• collecting the private identifiers of the plurality of terminals;
• constructing a group according to the collection of private identifiers submitted by the plurality of terminals;
• and
• calculating the key deriving parameter according to the group shared key, an additional parameter and said collection of private identifiers of the plurality of terminals,
• wherein each one of the plurality of terminals is configured to obtain the group shared key by executing the following step:
• performing an inverse operation in accordance with the key deriving parameter, the additional parameter and the private identifier of the corresponding one of the plurality of terminals, to obtain the group shared key.