Mobile Attachment Decryption via Server-Side Key Mediation

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Solution Overview

Problem

Mobile devices without native attachment viewers struggle to process messages with attachments encrypted using different session keys, as they cannot decrypt and render such attachments efficiently, leading to security risks and inefficiencies in bandwidth usage.

Innovation Solution

A system and method where encrypted session keys for message attachments are transmitted from remote servers to mobile devices, allowing decryption and rendering of requested attachments, with the decrypted session key transmitted back to the server to retrieve and send the attachment data in a device-friendly format.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If attachments are transmitted to mobile devices for viewing, then users can access attachment content, but bandwidth is wasted when attachments cannot be rendered due to lack of native viewers

Engineering Contradiction:
Improveattachment accessibilityVSAvoidbandwidth consumption
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The server performs preliminary actions by transmitting encrypted session keys and attachment metadata before the user requests the attachment. The server prepares the attachment for potential retrieval by having the decryption key ready, so that when the user requests an attachment, it can be quickly decrypted and transmitted without wasting bandwidth on attachments that won't be viewed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism where the server acts as a mediator between the user's attachment viewing request and the actual attachment data. The server transmits encrypted session keys and metadata as intermediaries that enable efficient attachment retrieval only when needed, preventing bandwidth waste while maintaining ease of access.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple attachments with different session keys are sent to mobile devices, then secure selective decryption is enabled, but device complexity increases due to multiple key management requirements

Engineering Contradiction:
ImprovesecurityVSAvoidkey management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the complexity of managing multiple session keys from the mobile device and places it on the server. Each attachment has its own session key encrypted with the user's public key, but the device only needs to manage its own private key. When the user requests an attachment, the server handles the decryption using the appropriate session key, reducing device complexity while maintaining security.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter of key management from device-side to server-side. Instead of requiring the mobile device to manage multiple decryption keys, the system transforms the architecture so that the server manages the session keys and performs decryption, while the device only needs to securely store its own private key for encrypting requests.

Inventive Principle:
Principle #35Parameter changes

3Loss of energy

If attachments are processed on remote servers before transmission, then bandwidth is conserved by not sending unviewable attachments, but processing time and server load increase

Engineering Contradiction:
Improvebandwidth conservationVSAvoidprocessing time
Core Design Contradiction:
Loss of energyVSLoss of time

Solution Approach 1:

The server performs preliminary processing by transmitting encrypted session keys and attachment metadata in advance, before the user requests the actual attachment. This preliminary action allows the server to prepare decryption capabilities without actually transmitting the attachment data, conserving bandwidth while minimizing processing time when the user requests an attachment.

Inventive Principle:
Principle #10Preliminary action

4Adaptability or versatility

If mobile devices without native viewers receive attachments, then attachment viewing capability is limited, but transmitting attachments in original format wastes bandwidth

Engineering Contradiction:
Improvedevice compatibilityVSAvoidbandwidth waste
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by transmitting attachments in their original format only when and where needed (when a user requests them), rather than converting all attachments to a universal format. The server handles format-specific decryption and transmission based on the user's device capabilities and requests, optimizing bandwidth usage while maintaining device compatibility.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2034687B1System and method for processing attachments to messages sent to a mobile device
Publication Date: 2012.06.13 BLACKBERRY LTD
  • EP2034687B1 patent drawingFigure 1
  • EP2034687B1 patent drawingFigure 2
  • EP2034687B1 patent drawingFigure 3

AI summary

A system and method for processing attachments to messages sent to a mobile device is described herein. Embodiments described herein apply to encrypted messages comprising multiple message parts, in which different encryption keys (e.g. session keys) have been used to encrypt the different message parts. In at least one example embodiment, the encrypted session keys for every message content part comprising an attachment is received at the mobile device. In one embodiment, all of the encrypted session keys are stored together in a main message header. The mobile device may then decrypt the encrypted session key associated with a user requested attachment, and transmits the decrypted session key to one or more remote servers in an attachment request for use in decrypting the requested attachment. Data associated with the requested attachment, in decrypted form, is returned to the mobile device.