PFS Protected MACsec Key Distribution via Dynamic KEK
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Solution Overview
Problem
Existing Media Access Control Security (MACsec) key distribution schemes are vulnerable to hacks due to their static key hierarchy, where the Connectivity Association Key (CAK) is used to derive the static Key Encrypting Key (KEK), compromising the entire key hierarchy if the root key is compromised.
Innovation Solution
Implementing Perfect Forward Secrecy (PFS) protected MACsec key distribution using the Diffie-Hellman (DH) key exchange to generate a dynamic Key Encrypting Key (KEK), which is unique for each communication session, thereby avoiding exposure of the final Diffie-Hellman key on a public channel and making it computationally difficult to derive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a static Key Encrypting Key (KEK) is used for key distribution, then the key hierarchy is simple and easy to manage, but the entire key hierarchy becomes vulnerable if the root key is compromised
Solution Approach 1:
The patent transforms the static KEK into a dynamic key by incorporating a session-specific random value (nonce) into the KEK derivation process. Each session generates a unique KEK using the formula: KEK = KDF(CAK || nonce), where CAK is the Connectivity Association Key and nonce is a session-specific random value. This dynamic approach ensures that even if one session's key is compromised, other sessions remain secure, resolving the contradiction between simplicity and security.
2Ease of operation
If the Key Encrypting Key (KEK) is derived from a static Connectivity Association Key Name (CKN), then key derivation is straightforward, but the KEK remains static and vulnerable to compromise
Solution Approach 1:
The patent changes the parameters used in KEK derivation by introducing a session-specific nonce alongside the static CKN. Instead of KEK = KDF(CAK || CKN), the new approach uses KEK = KDF(CAK || CKN || nonce). This parameter change maintains the ease of derivation through the existing KDF function while adding the nonce parameter ensures each session produces a unique, secure key, resolving the contradiction between operational simplicity and security reliability.
3Device complexity
If a single root key Connectivity Association Key (CAK) is used to derive all keys, then the key management is centralized and simple, but compromise of the root key exposes the entire key hierarchy
Solution Approach 1:
The patent segments the key hierarchy by introducing session-specific nonces that divide the single root key CAK into multiple isolated session keys. Each session's KEK and subsequent SAK are derived independently using their unique nonce, creating logical segmentation within the centralized structure. This ensures that compromise of one session's key does not affect other sessions, resolving the contradiction between centralized simplicity and vulnerability to hacks.
Data Source
AI summary
A non-transitory computer readable medium including instructions stored thereon, when executed, the instructions being effective to cause at least one processor of a first network device to: derive a private key encryption key based on a public key, a first private key of the first network device, a second private key of a live peer device, and a Connectivity Association Key (CAK); transmit a secret key encrypted by the private key encryption key to the live peer device; and receive a communication from the live peer device, the communication being encrypted by the secret key.