Patent ID: 7505945

Claim:
A method of electronically negotiating an electronic negotiable document, transferred along a chain of sellers and buyers, wherein said electronic negotiable document has a value which is an amount of money or quantity of goods, and wherein said seller is not a bank, the method comprising: issuing from a trusted supplier said seller with seller tamper-resistant document carrier hardware, said seller tamper-resistant document carrier hardware having its own public-secret key pair, and wherein said secret key is not accessible to said seller, said tamper-resistant document carrier hardware bearing said electronic negotiable document and a signature calculated using said secret key; issuing from a trusted supplier said buyer with buyer tamper-resistant document carrier hardware, said buyer tamper-resistant document carrier hardware having its own public-secret key pair, and wherein said secret key is not accessible to said buyer; transferring said electronic negotiable document from said seller tamper-resistant document carrier hardware to said buyer tamper-resistant document carrier hardware; splitting the original value of said electronic negotiable document electronically in said buyer tamper-resistant document carrier hardware by creating two or more split versions of said electronic negotiable document each with a new sequence number; inputting to said buyer tamper-resistant document carrier hardware, now acting as a seller tamper-resistant document carrier hardware, values defining values of each new said split version, wherein each new said split version comprises the signature of the original electronic negotiable document, and wherein each new said split version has a value such that the sum of the values of said two or more split versions adds up to said value of said original electronic negotiable document; digitally signing said split versions using said secret key of said buyer tamper-resistant document carrier hardware acting as a seller tamper-resistant document carrier hardware to generate a splitting signature; and transferring said two or more split versions separately to one or more further buyers without the involvement of a trusted third party; wherein each of said further buyers is able to transfer a said split version to one or more buyers in the chain.