Message-handling server and method for handling secure message attachments for a mobile device

1. A method performed by a server for handling secure message attachments for a mobile device, the method comprising:

receiving a secure message that includes an attachment, the secure message having a secure layer that indicates that the secure message is at least digitally signed;

providing the secure message without the attachment to the mobile device over a wireless network; and

receiving a request from the mobile device to access the attachment,

wherein in response to the request to access the attachment, the method comprises:

looking through the secure layer of the secure message at the server in order to locate the attachment within the secure message;

rendering an initial portion of the attachment by the server in a format for transmission over the wireless network for viewing by the mobile device; and

rendering an additional portion of the attachment by the server in the format for viewing the additional portion by the mobile device.

2. The method of claim 1 wherein the request includes an attachment identifier (ID) that identifies the attachment in accordance with a message-attachment indexing system, and

wherein the method includes the server performing an index lookup to find the attachment based upon the attachment ID.

3. The method of claim 1 , wherein when the secure layer further indicates that the secure message is encrypted, the method further includes:

receiving a session key from mobile device in the request; and

decrypting the secure message at the server using the session key to locate the attachment.

4. The method of claim 1 wherein the secure message is provided without the attachment to the mobile device over a virtual-private network (VPN) connection established between the server and the mobile device, and

wherein the initial portion of the attachment that is rendered by the server is provided over the VPN connection.

5. The method of claim 1 wherein the secure message is structured according to a security scheme such that the secure message is handled as an attachment by the server.

6. The method of claim 5 wherein the security scheme is a Secure Multipurpose Internet Mail Extensions (S/MIME) scheme.

7. The method of claim 1 wherein the request to access the attachment is provided to the server from the mobile device over the wireless network when either the secure message previously received by the mobile device is opened or when the mobile device receives an indication of a user intent to view the attachment.

8. The method of claim 1 wherein the initial portion of the attachment is rendered by the server in the format for transmission over the wireless network for viewing by the mobile device without transmission of the attachment to the mobile device,

wherein the format is selected by the server to be compatible for viewing on the mobile device based on characteristics of the mobile device, and

wherein the additional portion of the attachment is rendered by the server in response to an additional request to access the additional portion of the attachment.

9. The method of claim 1 wherein the attachment comprises at least one of a textual document, word processing document, audio file, image file, and video file.

10. The method of claim 1 , wherein the secure message has a plurality of attachments, and

wherein the attachment ID identifies which attachment of the plurality is being requested.

11. A method performed by a server for handling secure message attachments for a mobile device, the method comprising:

receiving, at the server, a secure message that includes an attachment, the secure message having a secure layer that indicates that the secure message is at least digitally signed;

providing the secure message without the attachment to the mobile device over a wireless network; and

receiving a request from the mobile device to access the attachment, the request including an attachment identifier (ID) that identifies the attachment in accordance with a message-attachment indexing system;

wherein in response to the request to access the attachment, the method comprises:

performing an index lookup to find the attachment based upon the attachment ID;

looking through the secure layer of the secure message at the server in order to locate the attachment within the secure message; and

rendering at least an initial portion of the attachment by the server in a format for viewing by the mobile device.

12. The method of claim 11 further comprising rendering an additional portion of the attachment by the server in the format for viewing the additional portion by the mobile device in response to an additional request to access the additional portion of the attachment.

13. The method of claim 12 wherein when the secure layer further indicates that the secure message is encrypted, the method further includes:

receiving a session key from mobile device in the request; and

decrypting the secure message at the server using the session key to locate the attachment.

14. The method of claim 13 wherein the secure message is provided without the attachment to the mobile device over a virtual-private network (VPN) connection established between the server and the mobile device, and

wherein the initial portion of the attachment that is rendered by the server is provided over the VPN connection.

15. A server configured to handle secure message attachments for a mobile device, the server configured to:

receive a secure message that includes an attachment, the secure message having a secure layer that indicates that the secure message is at least digitally signed;

provide the secure message without the attachment to the mobile device over a wireless network; and

receive a request from the mobile device to access the attachment;

wherein in response to the request to access the attachment, the server is further configured to:

look through the secure layer of the secure message at the server in order to locate the attachment within the secure message;

render an initial portion of the attachment by the server in a format for transmission over the wireless network for viewing by the mobile device; and

render an additional portion of the attachment by the server in the format for viewing the additional portion by the mobile device.

16. The server of claim 15 wherein the request includes an attachment identifier (ID) that identifies the attachment in accordance with a message-attachment indexing system, and

wherein the server is configured to perform an index lookup to find the attachment based upon the attachment ID.

17. The server of claim 15 , wherein when the secure layer further indicates that the secure message is encrypted, the server is further configured to:

receive a session key from mobile device in the request; and

decrypt the secure message at the server using the session key to locate the attachment.

18. The server of claim 15 wherein the secure message is provided without the attachment to the mobile device over a virtual-private network (VPN) connection established between the server and the mobile device, and

wherein the initial portion of the attachment that is rendered by the server is provided over the VPN connection.

19. The server of claim 15 wherein the secure message is structured according to a security scheme such that the secure message is handled as an attachment by the server.

20. The server of claim 19 wherein the security scheme is a Secure Multipurpose Internet Mail Extensions (S/MIME) scheme.

21. The server of claim 15 wherein the request to access the attachment is provided to the server from the mobile device over the wireless network when either the secure message previously received by the mobile device is opened or when the mobile device receives an indication of a user intent to view the attachment.

22. The server of claim 15 wherein the initial portion of the attachment is rendered by the server in the format for transmission over the wireless network for viewing by the mobile device without transmission of the attachment to the mobile device,

wherein the format is selected by the server to be compatible for viewing on the mobile device based on characteristics of the mobile device, and

wherein the additional portion of the attachment is rendered by the server in response to an additional request to access the additional portion of the attachment.

23. The server of claim 15 wherein the attachment comprises at least one of a textual document, word processing document, audio file, image file, and video file.

24. The server of claim 15 , wherein the secure message has a plurality of attachments, and

wherein the attachment ID identifies which attachment of the plurality is being requested.