Entrustable authentication encryption method

Abstract

The invention relates to an entrustable authentication encryption method. The method includes the following steps that: system parameters for encryption and decryption are generated; random numbers and system parameters are selected as the long-term private keys of users, wherein the long-term private keys include a private key of a sender, a private key of a receiver and a private key of a trustee; public keys are obtained according to the system parameters and the long-term private keys of the users, wherein the public keys include a public key of the sender, a public key of the receiver anda public key of the trustee; secret values shared by every two parties only are obtained through calculation; session keys are obtained according to the shared secret values and on the basis of the public key of the trustee, a temporary private key is randomly selected to encrypt a plaintext; the receiver uses the secret value shared with the sender to decrypt a ciphertext; and the trustee decrypts the ciphertext using its own private key.

Description

technical field [0001] The invention relates to a file authentication and encryption method. technical background [0002] With the comprehensive popularization of the Internet, information security has been paid more and more attention by people. In a secure cryptographic system, the key plays a vital role, and only legitimate users who have the key can perform encryption and decryption operations. In some specific environments, users are sometimes required to escrow the key to a trusted third party. For example, users may lose their own keys during the use of the service, resulting in previously encrypted files that cannot be decrypted. At this time, a backup of the key is required to restore the plaintext; Need, often need to get the user's key to decrypt the file. However, considering another important branch of cryptography——digital signature, in order to satisfy the non-repudiation of digital signature in the legal sense, only using a set of public / private key pairs...

AI Technical Summary

Problems solved by technology

However, considering another important branch of cryptography——digital signature, in order to satisfy the non-repudiation of digital signature in the legal sense, only using a set of public / private key pairs to realize the above services has natural defects.

In other words, asking users to submit their decrypted private keys to a trusted escrow center (EA: Escrowagency), although it solves the above problems, it brings another problem: in the traditional public key cryptosystem, the key used for signature The private key is the same as the private key used for decryption. Since the private key is no longer in the sole control of the user, when using the digital signature service, the user's signature will not be able to satisfy non-repudiation and lose the meaning of digital signature

However, in this scheme, users cannot choose the custodian by themselves, and the custodian can rely on its unique escrow decryption private key to decrypt the ciphertext of all users in the system, which is a passive scheme

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