초록 ▼

An encryption method and stored value system comprising a host computer, a reader/writer that communicates with the host computer, and an RF transponder that communicates with the reader/writer. The transponder comprises a transponder chip having a memory with a plurality of memory sections, which e

An encryption method and stored value system comprising a host computer, a reader/writer that communicates with the host computer, and an RF transponder that communicates with the reader/writer. The transponder comprises a transponder chip having a memory with a plurality of memory sections, which encryption method protects data stored in the memory. The method provides a secure way to increase and decrease the value stored the transponder and to selectively write and data to and from the transponder.

대표청구항 ▼

[ What is claimed is:] [1.] A stored value system comprising:an RF transponder retainable by an individual public user comprising a transponder chip including a transponder memory that stores transponder data therein including a stored value, and an RF transponder antenna for transmitting the transp

[ What is claimed is:] [1.] A stored value system comprising:an RF transponder retainable by an individual public user comprising a transponder chip including a transponder memory that stores transponder data therein including a stored value, and an RF transponder antenna for transmitting the transponder data and receiving commands;a reader/writer physically accessible to a plurality of the individual public users for communicating with the transponder by way of the RF transponder antenna, including receiving the transponder data from the transponder and transmitting commands to the transponder;a secure central host computer remotely positioned relative to the reader/writer and physically inaccessible to the plurality of individual public users for communicating with a plurality of the reader/writers, for transforming the transponder data and for generating a secret key, a public key, and an encrypted validation signature from the secret key and the transformed transponder data, wherein the central host computer includes a host computer memory for storing the secret key and the public key; anda communications link between the central host computer and the reader/writer for communicating the encrypted validation signature and public key from the central host computer to the reader/writer and for communicating the transponder data from the reader/writer to the central host computer, wherein the reader/writer includes means for transforming the transponder data, for decrypting the encrypted validation signature using the public key, comparing the decrypted validation signature to the transformed transponder data and transmitting a value change command for the stored value in response to a match between the decrypted validation signature and the transformed transponder data.