Digital signatures for tangible medium delivery
First Claim
1. A method for a sender to send an encrypted message to an authorized recipient, the method having steps comprising:
- creating an encrypted content message that may be decrypted using a content decryption key that is unknown to the authorized recipient;
creating an encrypted authentication message that may be decrypted using a recipient'"'"'s key wherein the recipient'"'"'s key is known to the authorized recipient but unknown to others except perhaps known to the sender;
fixing the encrypted authentication message and the encrypted content message onto a tangible medium and thereafter permitting the authorized recipient to obtain the tangible medium;
if a valid reply has been received, wherein the valid reply is based upon the decrypted authentication message, then allowing the authorized recipient to obtain said content decryption key.
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Accused Products
Abstract
The invention provides a method for a sender to send a message on a tangible medium and ensure that it is privacy protected until verification that the medium has been received by the authorized recipient. The invention provides a method in which a sender creates an encrypted content message that may be decrypted using a content decryption key that is unknown to the authorized recipient. The sender creates an encrypted authentication message that may be decrypted using a recipient'"'"'s key that is known to the authorized recipient but is unknown to others, except perhaps to the sender. The sender fixes the encrypted content message and the encrypted authentication message onto a tangible medium and then permits the authorized recipient to obtain the tangible medium. The authorized recipient uses the recipient'"'"'s key to decrypt the encrypted authentication message and then creates a valid reply that is based upon or which uses the decrypted authentication message. The authorized recipient sends the valid reply to the sender and upon verification that the reply is valid the sender allows the authorized recipient to obtain the content decryption key. With the content decryption key, the authorized recipient is able to decrypt the encrypted content message. The invention also includes an article of manufacture for sending an encrypted message from a sender to an authorized recipient using a method, of the invention.
158 Citations
31 Claims
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1. A method for a sender to send an encrypted message to an authorized recipient, the method having steps comprising:
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creating an encrypted content message that may be decrypted using a content decryption key that is unknown to the authorized recipient; creating an encrypted authentication message that may be decrypted using a recipient'"'"'s key wherein the recipient'"'"'s key is known to the authorized recipient but unknown to others except perhaps known to the sender; fixing the encrypted authentication message and the encrypted content message onto a tangible medium and thereafter permitting the authorized recipient to obtain the tangible medium; if a valid reply has been received, wherein the valid reply is based upon the decrypted authentication message, then allowing the authorized recipient to obtain said content decryption key. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An article of manufacture for sending an encrypted message from a sender who possesses a content decryption key to a recipient who possesses a recipient'"'"'s key, the article, comprising:
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a tangible medium; an encrypted content message fixed on said tangible medium, wherein said encrypted content message may be decrypted using the content decryption key; an encrypted authentication message fixed on said tangible medium, wherein said encrypted authentication message may be decrypted using the recipient'"'"'s key; whereby after the article is delivered to the recipient the recipient may use the recipient'"'"'s key to decrypt said encrypted authentication message into a decrypted authentication message, the recipient may use the decrypted authentication message to send a valid reply to the sender confirming that the recipient received said article and the sender may then allow the recipient to obtain the content decryption key. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for an authorized recipient to receive an encrypted message from a sender, the method having steps comprising:
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receiving a tangible medium from the sender wherein the tangible medium has fixed upon it an encrypted authentication message and an encrypted content message; using a recipient'"'"'s key to decrypt the encrypted authentication message into a decrypted authentication message, wherein the recipient'"'"'s key is known to the authorized recipient but unknown to others except perhaps known to the sender; creating a valid reply using the decrypted authentication message; sending the valid reply to the sender; if the recipient has received a content decryption key from the sender, then using the content decryption key to decrypt the encrypted content message. - View Dependent Claims (28, 29, 30, 31)
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Specification