Contract Certificate Private-Key Installation With AES-GCM and ECDH
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Solution Overview
Problem
Existing communication technologies for electric vehicles face security threats due to the difficulty in verifying a trusted certification authority in real time and vulnerability to unauthorized access, particularly when using TLS and electronic signatures without a trusted platform module (TPM), necessitating a secure method for transmitting and installing contract certificate private keys.
Innovation Solution
A method and apparatus for encrypting and decrypting contract certificate private keys using AES-Galois/counter mode (GCM) based on ECDH protocol, ensuring high confidentiality and reliability in the vehicle-to-grid environment, utilizing a public key encryption method for secure communication between the EVCC and secondary actors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If TLS and electronic signatures are used without TPM, then communication can be established, but security is vulnerable to unauthorized access
Solution Approach 1:
The patent introduces a certificate installation process as an intermediary mechanism that establishes a trusted communication channel before actual TLS communication begins. The EVCC obtains and installs certificates from a trusted authority through a secure provisioning process, which then enables secure TLS communication. This intermediary step resolves the contradiction by preparing the security credentials in advance through a controlled process.
Solution Approach 2:
The patent performs preliminary security setup by installing certificates and private keys in the EVCC before actual charging operations begin. The certificate installation request and response messages are exchanged in advance to establish the security context. This preliminary action ensures that when TLS communication occurs, the security credentials are already in place, preventing unauthorized access while enabling smooth communication.
2Ease of manufacture
If contract certificate private key is transmitted without encryption, then installation is simple, but confidentiality is compromised
Solution Approach 1:
The patent applies different quality levels to different parts of the certificate installation process. The certificate data itself is transmitted in plain text for ease of installation, while the private key component is encrypted with AES-GCM using a derivation key. This local differentiation allows the certificate to be installed simply while the sensitive private key portion maintains high confidentiality through encryption.
Solution Approach 2:
The patent creates a composite transmission structure where the certificate installation response message contains both unencrypted certificate data and encrypted private key data. The encrypted private key is wrapped with a derivation key that only the EVCC can unlock using its ECDH public key. This composite approach combines the simplicity of plain text transmission with the security of encrypted sensitive elements.
3Reliability
If AES-GCM with ECDH is used for encryption, then confidentiality is high, but device complexity increases
Solution Approach 1:
The EVCC performs self-service by generating its own ECDH key pair and using its public key to decrypt the encrypted private key. The system leverages the EVCC's inherent cryptographic capabilities to derive the decryption key without requiring external assistance. This self-service approach reduces overall system complexity by eliminating the need for additional key management infrastructure while maintaining high confidentiality through AES-GCM encryption.
Data Source
AI summary
Disclosed are a method and device for installing a certificate on the basis of encryption and decryption of a contract certificate private key for an electric vehicle communication controller. The method for installing the certificate comprises: a step in which the electric vehicle communication controller transmits, to a secondary actor, a certificate installation request message signed with a private key associated with a manufacturer's provisioning certificate; and a step of receiving, from the secondary actor, a certificate installation response message signed with a private key associated with a leaf certificate of a certificate provisioning service, wherein an encrypted private key element of the certificate installation response message stores a private key belonging to a new contract certificate which is encrypted for the electric vehicle communication controller without a trust platform module, the private key belonging to the new contract certificate is encrypted with AES-GCM-256 on the basis of an encryption key which is entered from a public key of the manufacturer's provisioning certificate and generated through an ECDH protocol, and the private key encrypted with the AES-GCM-256 is included in a ciphertext at 528-bits or 448-bits after an initial initialization vector of a contract certificate data packet.