EV Certificate Provisioning Without TPM Using ECDH and AES-GCM
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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, especially when connected through networks, and are vulnerable to unauthorized access, necessitating a method for securely transmitting and installing a contract certificate private key without a trusted platform module.
Innovation Solution
A method and apparatus for installing a certificate based on encryption and decryption of a contract certificate private key using AES-Galois/counter mode (AES-GCM) encryption, generating an encryption key through the ECDH protocol, ensuring high confidentiality and reliability of the private key transmission to the EVCC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AES-GCM encryption with ECDH protocol is used to encrypt the contract certificate private key, then the security and confidentiality of private key transmission is improved, but the device complexity and computational overhead increase
Solution Approach 1:
The patent introduces an encryption key as an intermediary element that bridges the sender and receiver. The encryption key is generated through ECDH key exchange protocol, acting as a mediator that enables secure communication without directly exposing the private key. This intermediary mechanism resolves the contradiction by providing security through cryptographic protocols rather than direct private key transmission.
Solution Approach 2:
The patent changes the parameter of encryption mode from traditional AES to AES-GCM, which provides both confidentiality and authentication. This parameter change improves security by ensuring both encryption and integrity verification, while the GCM mode's efficiency helps manage computational overhead. The patent also parameters the initialization vector to be 128 bits and transmitted in specific message fields, optimizing the balance between security and system complexity.
2Reliability
If the initialization vector is randomly generated and transmitted in the message for certificate installation, then the security against replay attacks is improved, but the risk of IV reuse increases if not properly managed
Solution Approach 1:
The patent performs preliminary action by generating the initialization vector randomly before the encryption process and embedding it in the encrypted private key data structure. This preliminary generation and inclusion of the IV ensures that each encryption operation uses a unique IV, preventing replay attacks. The IV is prepared in advance and transmitted along with the encrypted data, ensuring its proper usage and preventing reuse issues.
3Adaptability or versatility
If the contract certificate data packet is transmitted through multiple intermediaries (MO to CPS to EVCC), then the flexibility and scalability of the system is improved, but the vulnerability to unauthorized access and security threats increases
Solution Approach 1:
The patent uses multiple cryptographic intermediaries to protect data through the transmission chain. The encryption key acts as a cryptographic mediator that protects the private key throughout its journey from MO to CPS to EVCC. Each intermediary (MO, CPS, EVCC) has specific cryptographic responsibilities, creating a chain of trust that maintains security while enabling flexible multi-hop transmission. The signature of the CPS guarantees data authenticity at each transmission stage.
Solution Approach 2:
The patent applies different security measures at different stages of transmission. The encryption key is generated and used specifically for protecting the private key during transmission, while the CPS adds its own signature for authentication. This local application of different cryptographic qualities at different transmission stages provides tailored security protection appropriate to each intermediary's role, maintaining overall security while enabling system flexibility.
Data Source
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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.