04926480 is referenced by 320 patents and cites 16 patents.

A user controlled card computer C and communicating tamper-resistant part T are disclosed that conduct secure transactions with an external system S. All communication between T and S is moderated by C, who is able to prevent T and S from leaking any message or pre-arranged signals to each other. Additionally, S can verify that T is in immediate physical proximity. Even though S receives public key digital signatures through C that are checkable using public keys whose corresponding private keys are known only to a unique T, S is unable to learn which transactions involve which T. It is also possible for S to allow strictly limited messages to be communicated securely between S and T.

Card-computer moderated systems
Application Number
Publication Number
Application Date
May 24, 1988
Publication Date
May 15, 1990
David Chaum
14652 Sutton St., Sherman Oaks, 91403
Nixon & Vanderhye
H04K 1/00
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