Abstract: An information using device 300 adds an encryption public key held to a blockchain, an information holding device 200 transmits encrypted information as a result of acquiring the encryption public key from the blockchain 400 and encrypting the target information, the information management device 100 stores the encrypted information received, and transmits a storage destination address, the information holding device 100 adds the storage destination address of the encrypted information received to the blockchain 400, the information using device 300 acquires the storage destination address of the encrypted information, and accesses the storage address, the information management device 100 transmits the encrypted information at the storage destination address, in response to the access from the information using device 300, and the information using device 300 decrypts the encrypted information received, using an encryption secret key held.

Abstract: An information using device 300 adds an encryption public key held to a blockchain, an information holding device 200 transmits encrypted information as a result of acquiring the encryption public key from the blockchain 400 and encrypting the target information, the information management device 100 stores the encrypted information received, and transmits a storage destination address, the information holding device 100 adds the storage destination address of the encrypted information received to the blockchain 400, the information using device 300 acquires the storage destination address of the encrypted information, and accesses the storage address, the information management device 100 transmits the encrypted information at the storage destination address, in response to the access from the information using device 300, and the information using device 300 decrypts the encrypted information received, using an encryption secret key held.

Abstract: Provided is an investment management proposal system that proposes a suitable investment management algorithm and portfolio which flexibly respond to the diverse needs of an investor. A representative embodiment of the present invention is an investment management proposal system that proposes, to a user, investment management in respect to a financial product, the investment management proposal system having a plurality of types of prerecorded algorithms pertaining to investment management which can be called from a program, and having a determination engine which receives the input of information pertaining to an investment stance from the user and selects at least one suitable algorithm on the basis of the input investment stance information.