Digital signature is the core technical basis of electronic signature. Digital signature is based on encryption technology, using public key encryption algorithm and hash function. Common digital signature algorithms are: RSA, DSS, ECDSA, ELGamal, Schnorr, etc. There are also some special-purpose digital signatures, such as blind signature, group signature, failed termination signature and so on.
The core technology of electronic signature is modern cryptography based on public key system. It is also one of the important applications of digital signature technology. Electronic signature (including digital certificate, private key and seal picture) is stored in a secure password ic card, and the private key cannot be derived from the IC card. When electronic signature is carried out, different signature software is needed according to different signature objects. Electronic signature system displays the traditional seal and handwritten signature in digital form, and relies on PKI/CA platform to ensure the security of electronic signature and the entity where the signature is located by using digital signature technology. For the electronic signature system embedded with office software (such as Word, Excel, etc.). ), the main technical difficulty lies in how to ensure that it can independently control the security of signatures and official documents, without relying on the security of the host. For example, it is necessary to ensure that the signed official document cannot be illegally modified or allowed, but it can be copied and inserted into other official documents; Once the signature document is maliciously tampered with, the system should find and identify it in time. For electronic signatures based on web pages, the transmission security and centralized management of signatures are important parts to be considered. For other non-embedded electronic signature systems (for example, electronic signature can be realized in a special file format through document format conversion), how to integrate with the user's office environment and make it as convenient as possible for users to use is a key point. Electronic signature is implemented according to public key system.