Electronic negotiable documents
A method of issuing an electronic negotiable document (END) comprising: creating as data an END and storing this in a tamper-resistant document carrier, the document carrier containing a unique public-secret key pair for signing and verifying and a unique document carrier identifier; signing the unique document-carrier identifier, the END and an END identifier using the secret key of the public-secret key pair and storing the result in the document carrier.
1. 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.
2. The method as claimed in claim 1 wherein said seller and said buyer tamper-resistant document carrier hardware each have a document carrier identifier, and wherein each said document carrier identifier is signed by a said secret key.
3. The method as claimed in claim 1 wherein said seller tamper-resistant document carrier hardware bears an issuing signature, and wherein said transferring includes transferring said issuing signature from said seller tamper-resistant document carrier hardware to said buyer tamper-resistant document carrier hardware.
4. The method as claimed in claim 3 further comprising deleting said issuing signature after said transferring.