Secure messaging system with return receipts

• US 6,807,277 B1
• Filed: 06/12/2000
• Issued: 10/19/2004
• Est. Priority Date: 06/12/2000
• Status: Active Grant

• Current Assignee: Surety, LLC
• Original Assignee: Surety, LLC
• Inventors: Wettlaufer, Albert J., Doonan, Wes
• Primary Examiner(s): Darrow, Justin T.
• Application Number:
  US09/591,686
• Time in Patent Office: 1,590 Days
• Field of Search: 380/29, 380/30, 380/27, 380/28, 380/282, 380/286, 713/155, 713/165, 713/168, 713/170, 713/201, 705/53
• US Class Current: 380/281
• CPC Class Codes: H04L 63/0442 wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30
• CPC Class Codes: H04L 63/0823 using certificates cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263

Abstract

A method and system for electronic messaging in which a sender of an electronic message receives a return receipt, without having to send the message contents to a third party. The sender contacts a server to obtain an encryption key to encrypt the message. The server returns an encryption key along with key retrieval information to the sender. The key retrieval information can be used to obtain from the server the decryption key corresponding to the returned encryption key. The sender encrypts the message using the encryption key and sends the message, along with the key retrieval information, to the recipient. The recipient sends the key retrieval information to the server to retrieve the corresponding decryption key. The recipient then decrypts the encrypted message received from the sender using the decryption key. When the recipient sends a request to obtain the decryption key, the server notifies the sender when the key has been successfully retrieved. The fact that the decryption key was retrieved by the recipient indicates to the sender that the recipient received the message.

Claims

1. An electronic messaging system having a return receipt feature, the system comprising a sender computer, a server computer and a recipient computer, wherein:

the sender computer is configured to send to the server computer, an issue request to have an encryption key issued;

the server computer is configured to receive the issue request, issue a first encryption key and key retrieval information to the sender computer in response to the issue request, and store a first decryption key corresponding to the first encryption key in an associated memory whose location is referenced by said key retrieval information;

the sender computer is further configured to encrypt a message using the first encryption key to thereby form an encrypted message, and send the encrypted message along with the key retrieval information to the recipient computer;

the recipient computer is configured to receive the encrypted message and the key retrieval information, and send to the server computer a retrieval request including the key retrieval information to obtain the corresponding first decryption key; and

the server computer is further configured to receive the retrieval request from the recipient computer, send to the recipient computer the corresponding first decryption key, as indicated by the key retrieval information sent by the recipient computer, and notify the sender computer that the corresponding first decryption key was retrieved by the recipient.

2. The electronic messaging system according to claim 1, wherein the sender computer is further configured to encrypt at least the key retrieval information with a second encryption key which is different from the first encryption key, prior to sending the key retrieval information to the recipient computer.

3. A method for operating a server computer configured to provide a receipt message to a first computer, after receiving a request for information from a second computer, the method comprising:

a step of receiving a key issue request to provide an encryption key to a first party;

a step of sending a first encryption key to the first party along with key retrieval information leading to a first decryption key for decrypting a message encrypted using the first encryption key;

a step of receiving a retrieval request from a second party different from the first party, the retrieval request including the key retrieval information;

a step of sending the first decryption key information to the second party; and

a step of notifying the first party after receiving the retrieval request from the second party.

4. A method according to claim 3, wherein the first encryption key and the first decryption key are the same.

5. A method according to claim 3, wherein the first encryption key and the first decryption key are different yet related through an asymmetric encryption algorithm.

6. A method according to claim 3, wherein the issue request and the retrieval request are both received via the Internet.

7. A method according to claim 3, further comprising:

a step of generating a first encryption key in response to the issue request;

a step of arranging the first encryption key and the key retrieval information into a response message;

a step of sending the response message to the first party; and

a step of updating a record with information related to the first encryption key that was sent.

8. A computer readable medium storing executable software code thereon, the executable software code including:

code to receive an issue request to provide an encryption key to a first party;

code to send a first encryption key to the first party along with key retrieval information leading to a first decryption key for decrypting a message encrypted with first encryption key;

code to receive a retrieval request from a second party, the retrieval request including the key retrieval information;

code to send the first decryption key to the second party; and

code to notify the first party after receiving the retrieval request from the second party.

9. The computer readable medium of claim 8, further comprising:

code to generate the first encryption key in response to the issue request;

code to arrange the first encryption key and the key retrieval information into a response message;

code to send the response message to the first party; and

code to update A record with information related to the first encryption key that was sent.

10. A method for operating a first computer configured to send a message to a recipient and receive a receipt message in response thereto, the method comprising:

a step of sending a key issue request to obtain an encryption key;

a step of receiving a first encryption key along with key retrieval information leading to a first decryption key from a key server for decrypting a message encrypted using the first encryption key;

a step of encrypting a message with the first encryption key to form an encrypted message;

a step of sending the encrypted message and the key retrieval information to the recipient; and

a step of receiving confirmation from the key server signifying that an attempt was made to retrieve the first decryption key.

11. The method according to claim 10, further comprising a step of encrypting at least the key retrieval information using a second encryption key which is different from the first encryption key, prior to sending the key retrieval information to the recipient.

12. A computer readable medium storing executable software code thereon, the executable software code including:

code to send a key issue request to obtain an encryption key;

code to receive a first encryption key along with key retrieval information leading to a first decryption key from a key server for decrypting a message encrypted using the first encryption key;

code to encrypt a message with the first encryption key to form an encrypted message;

code to send the encrypted message and the key retrieval information to a recipient; and

code to receive confirmation from the key server signifying that an attempt was made to retrieve the first decryption key.

13. The computer readable medium of claim 12, further comprising:

code to encrypt at least the key retrieval information using a second encryption key which is different from the first encryption key, prior to sending the key retrieval information to the recipient.