Proxy Device TLS Handshake Traffic Control

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Solution Overview

Problem

Firewalls struggle to inspect and apply policy decisions to encrypted network traffic, requiring resource-intensive decryption and facing regulatory restrictions, especially in secure communications where they cannot view network traffic in its entirety without first decrypting messages.

Innovation Solution

A proxy device intercepts the initial message of a handshaking procedure, extracts server name identification information, and applies policies based on this information without decrypting the message data, allowing or denying connections and controlling traffic without decrypting, thereby conserving network and computational resources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If the firewall decrypts encrypted network traffic to inspect and apply policy decisions, then the firewall can view and control network traffic, but resource consumption increases and regulatory restrictions are violated

Engineering Contradiction:
Improvevisibility of network trafficVSAvoidcomputational resources
Core Design Contradiction:
Loss of informationVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the necessary identification information (SNI extension) from the encrypted TLS handshake process, allowing the firewall to identify and apply policies to specific traffic without decrypting the entire encrypted payload. This selective extraction maintains traffic visibility while avoiding the computational overhead of full decryption.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The firewall performs policy evaluation during the TLS handshake phase, before the actual encrypted data transmission begins. By intercepting and analyzing the SNI extension in the initial handshake messages, the firewall can make policy decisions upfront without needing to decrypt subsequent data traffic.

Inventive Principle:
Principle #10Preliminary action

2Loss of information

If the firewall decrypts encrypted network traffic to inspect and apply policy decisions, then the firewall can view and control network traffic, but regulatory restrictions are violated

Engineering Contradiction:
Improvevisibility of network trafficVSAvoidcompliance with regulations
Core Design Contradiction:
Loss of informationVSAdaptability or versatility

Solution Approach 1:

The firewall extracts only the minimal necessary information (SNI extension) from the encrypted traffic to apply policies, avoiding full decryption. This approach maintains compliance with regulations that restrict decryption of sensitive traffic while still enabling policy enforcement based on server identification.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of operation

If the firewall performs deep packet inspection on encrypted traffic, then the firewall can apply policy decisions, but decryption is required which consumes resources

Engineering Contradiction:
Improvepolicy application capabilityVSAvoidcomputational resources
Core Design Contradiction:
Ease of operationVSUse of energy by moving object

Solution Approach 1:

Instead of performing deep packet inspection that requires decryption, the firewall extracts the SNI extension from the TLS handshake process. This provides sufficient information for policy decisions without the need for resource-intensive decryption of the encrypted payload.

Inventive Principle:
Principle #2Taking out (Extraction)

4Productivity

If the firewall allows traffic to pass through before applying policy decisions, then encrypted traffic can flow, but the firewall cannot inspect the traffic content

Engineering Contradiction:
Improvetraffic flow efficiencyVSAvoidtraffic inspection capability
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The firewall performs inspection of the SNI extension during the TLS handshake phase, before allowing the encrypted data traffic to flow. This preliminary inspection provides traffic inspection capability without blocking productivity, as the policy decisions are made upfront based on server identification.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2850770B1Transport layer security traffic control using service name identification
Publication Date: 2019.12.18 CISCO TECHNOLOGY INC
  • EP2850770B1 patent drawingFigure 1
  • EP2850770B1 patent drawingFigure 2
  • EP2850770B1 patent drawingFigure 3

AI summary

Traffic control techniques are provided for intercepting an initial message in a handshaking procedure for a secure communication between a first device and a second device at a proxy device. Identification information associated with the second device is extracted from the initial message. A policy is applied to communications between the first device and second device based on the identification information.