During the production of an electronic official seal, key security is crucial for ensuring its legal validity and data integrity. As the "digital DNA" of the electronic official seal, keys operate throughout the seal's entire lifecycle, from generation to storage, use, and verification. Their security requires coordinated protection across multiple dimensions, including technical, managerial, and physical aspects.
Key generation requires the use of high-strength algorithms and a secure environment. Key pairs for electronic official seals are typically generated using asymmetric cryptography, such as RSA or ECC. The former is widely used due to its maturity, while the latter offers comparable security with a shorter key length and is becoming the mainstream choice. The generation process must be performed within a hardware security module (HSM) or a trusted execution environment (TEE). These physically isolated devices prevent key theft or tampering during the generation phase. For example, platforms like Tencent E-Signature use HSMs to store private keys, ensuring that keys are kept in a controlled environment from the moment they are generated, preventing them from being exposed in plaintext.
Key storage requires a combination of encryption and access control. Generated private keys must be stored in encrypted form, and encryption keys must be managed separately from stored keys. Some platforms employ a layered encryption strategy, such as using a master key to encrypt data keys, which in turn protect private keys, creating a "key chain" of protection. Furthermore, storage media must be tamper-resistant, such as smart cards or USB keys. These devices have built-in security chips that can detect physical attacks and automatically destroy keys. Access to private keys requires multi-factor authentication, such as a digital certificate, a PIN, and biometrics, to prevent a single authentication method from being compromised.
Key usage must be strictly restricted and audited. The electronic official seal system should implement role-based access control (RBAC), assigning key operation permissions to specific roles. For example, administrators are responsible for key backups, while operators can only access keys for signing. Each access must record information such as the time of operation, IP address, and purpose of use. For example, platforms like eSignbao use log auditing to track key usage throughout its lifecycle. Any unusual access (such as signing during off-hours) triggers an immediate alert and freezes the key.
Key transmission must utilize secure protocols and temporary key mechanisms. If keys are accessed remotely, the transmission must utilize encrypted channels such as SSL/TLS to prevent man-in-the-middle attacks. In some scenarios, the system generates a temporary session key to encrypt private key fragments during transmission. After the session ends, the temporary key is automatically destroyed to prevent long-term exposure. For example, in government systems, cross-departmental calls for electronic official seals are often implemented through secure middleware, ensuring that keys remain encrypted during transmission.
Key renewal and revocation mechanisms are crucial for ongoing security. Keys for electronic official seals must be regularly replaced to reduce the risk of leakage from long-term use. During renewal, the old key must be revoked and the revocation time recorded. After the new key is generated, it must be re-bound to the digital certificate. Revoked keys must be included in the Certificate Revocation List (CRL) for verification by validators. For example, in the financial industry, electronic insurance policy seal keys are typically updated quarterly. Revoked keys are synchronized to the industry-wide CRL within 24 hours to prevent malicious reuse.
Physical security and disaster recovery design are the final line of defense for key protection. Hardware devices storing keys must be located in a controlled computer room equipped with fire, moisture, and electromagnetic interference protection, and physical access must be restricted. Keys must also be backed up off-site, using off-site storage, such as encrypted hard drives sealed in fireproof safes, to ensure rapid recovery in the event of a master key vault compromise. For example, some large platforms deploy key backup nodes in three different geographic locations, ensuring that the overall security remains intact even if any one node is compromised.
