When exchanging information on the Internet, it is necessary to use cryptography to ensure security. Representative encryptions are symmetric key and public key encryption. A new advanced encryption is being researched.
Public key encryption solves the problem of key sharing in symmetric key encryption. However, when using a public key encryption, the information sender must obtain the receiver's public key to encrypt a message in advance. Advanced network systems, like cloud computing system, require a more sophisticated encryption scheme. We call the encryption that satisfies this requirement "fine-grained encryption."
This new encryption scheme achieves the most advanced logic in the encryption-decryption mechanism. We have created the world's first functional encryption that can use arbitrary logical expression judgment during encryption-decryption and also can provide realistic safety. Fine-grained encryption makes an encrypted information possible to configure access control for the encrypted information by itself ? for example, to set an access contorol that the document can only be decrypted by the director or the personnel devision's manager.
Our team now plans to study how to efficiently implement and utilize this scheme for various applications.
Example of use of confidential information sharing within an enterprise of fine-grained encryption
- Tatsuaki Okamoto, Katsuyuki Takashima, "Fully Secure Functional Encryption with General Relations from the Decisional Linear Assumption", CRYPTO 2010, pp.191-208 (2010)