Symmetric Key Distribution Protocol (SKDP)

Introduction

SKDP is a next-generation protocol designed to solve one of the most challenging problems in cryptography: secure key distribution. With the growth of the Internet as a global communications medium, traditional methods based on a single pre-shared symmetric key are increasingly vulnerable. In these systems, if a device or server key is compromised, an attacker may decrypt all encrypted communications—past, present, and future. Additionally, such systems often lack forward secrecy, meaning that the compromise of a session key can expose all historical communications.

SKDP Help Documentation
SKDP Protocol Specification
SKDP Summary Document

Statement of the Problem

Traditional key distribution schemes using pre-shared symmetric keys suffer from several issues:

• Scalability:
  A single pre-shared key or a centralized key database creates a bottleneck. Its compromise can endanger the entire network.

• Single Point of Failure:
  If an attacker captures a device's embedded key or the server's key database, all messages can be instantly decrypted.

• Lack of Forward Secrecy:
  Without mechanisms to refresh keys, the capture of a session key can expose all previous communications.

The SKDP Solution

SKDP proposes a novel approach that leverages robust symmetric cryptographic primitives with longer key lengths, making the underlying problem far more computationally expensive—and potentially infeasible—to break. Key aspects of the SKDP solution include:

• Authentication & Token Exchange:
  Pre-shared keys are used primarily for authentication and for encrypting secret tokens exchanged between the server and the client.

• Ephemeral Session Keys:
  Secret tokens are used to derive ephemeral session keys that encrypt the actual message streams. This ensures that the compromise of a device's embedded key or the server's key database does not compromise past communications.

• Forward Secrecy:
  Each session is encrypted with a unique, ephemeral key that cannot be derived from the pre-shared key alone.

Hybrid Security Model

SKDP can be combined with a quantum secure protocol (such as QSMP) that periodically injects fresh entropy into the system. This hybrid approach not only enhances overall security but also provides true long-term security—even in the face of advancements in quantum computing.

Scalability and Network Management

One of the key strengths of SKDP is its scalability. Using a single master key, SKDP can securely manage millions of devices through a hierarchical key derivation scheme:

• Hierarchical Key Derivation:

  • A master key is used to derive branch keys.
  • Each branch key, in turn, is used to derive individual device keys.

• Flexible Connectivity:
  Any branch can securely connect with any client on another branch, provided they share the branch identification. This tree-like derivation minimizes the risk associated with a centralized key database and reduces the impact of any individual key compromise.

Applications

SKDP is ideal for a wide range of applications, including:

• Institutional transaction-based protocols (e.g., keys embedded on debit or credit cards).
• Communication systems that distribute keys via pluggable memory-storage devices with a central hub managing secure connections.
• Large-scale networks requiring the secure management of millions of devices from a single master key.

Conclusion

By leveraging robust symmetric cryptographic primitives and a scalable, hierarchical key derivation scheme, SKDP provides forward secrecy and addresses many of the vulnerabilities inherent in traditional pre-shared key systems. Its design mitigates the risk of mass compromise, ensuring that even if a device's key or a server's key is exposed, past communications remain secure. SKDP represents a significant advancement in secure key distribution, offering long-term security in an era of rapidly evolving cryptographic threats and quantum computing.

License

ACQUISITION INQUIRIES: QRCS is currently seeking a corporate acquirer for this technology. Parties interested in exclusive licensing or acquisition should contact: [email protected]

PATENT NOTICE: One or more patent applications (provisional and/or non-provisional) covering aspects of this software have been filed with the United States Patent and Trademark Office (USPTO). Unauthorized use may result in patent infringement liability.

QRCS-PL private License. See license file for details.
Software is copyrighted and SKDP is patent pending. Written by John G. Underhill, under the QRCS-PL license, see the included license file for details. Not to be redistributed or used commercially without the author's expressed written permission. All rights reserved by QRCS Corp. 2025.