Abstract: A first computer, in data registration processing: determines a type of biometric information for encryption with which the data is to be encrypted; acquires the determined type of biometric information for encryption from a user of the first computer; generates, from each piece of the acquired biometric information for encryption, a public key based on a predetermined algorithm; transmits the public key to a second computer; and transmits the data encrypted with the public key to the third computer, the first computer, in data presentation processing: acquires the encrypted data from a third computer; acquires the determined type of biometric information for decryption from the user of the first computer; generates, from each piece of the acquired biometric information for decryption, a private key based on the predetermined algorithm; decrypts the encrypted data with use of the private key; and presents each piece of the decrypted registered data.

Abstract: A product and the like can be managed after trading the product and the like to reduce trade risks. A trade management system includes a node having a calculating unit that performs, with transaction data issued by a predetermined node on an occasion of selling a predetermined product being set as a start point, processing for determining whether or not a commercial trade is valid on the basis of information on a trade condition of the product included in transaction data at the start point, and preliminarily held party-in-charge information relating to the party in charge when performing each processing of a series of commercial trades for repeating purchase and sale of the product.