A digital certificate is a file digitally signed by a certificate authority, which contains public key owner information and public key. Electronic signature products, only by obtaining three qualifications about password products and using certified CA digital certificates, can have legal compliance. In the digital certificate, the information that can be found is the issuing authority of the certificate, the signing time, the validity period of the certificate and so on. All CA certificates adopt national uniform standards, and there is no difference.

Digital certificate (source: e-sign treasure)

Therefore, digital certificates can solve the problem of forging public keys, which are issued by the authoritative organization CA, also known as certificate authority, and can be used to identify the other party's identity on the Internet.

CA will hash the contents of the user certificate, and then use its own private key to asymmetrically encrypt the calculated digest. CA's public key is public. Users can decrypt the original digest encrypted by CA private key with CA public key, and get the content of the original user certificate at the same time, and then use the same hash algorithm to get a digest value. Comparing the two digest values, it is consistent that they have not been tampered with and can be trusted, thus ensuring the legitimacy and non-tampering of the certificate.

CA certificate verification

2. Electronic signature

China's "Electronic Signature Law" defines that an electronic signature refers to the data contained in the data message in electronic form, and attached with the data used to identify the identity of the signer and indicate the content approved by the signer. Simply put, electronic signature is actually a digital certificate composed of handwritten signature or enterprise signature, plus a string of encrypted data or codes. These data or codes can show the real identity information of the signer.

Electronic signature (source: electronic signature)

Therefore, electronic signature is an electronic technical means that can identify the true identities of both signatories in electronic documents, ensure the security, authenticity and non-repudiation of signatures, and play the same role as handwritten signatures or seals.

3. Electronic signature

Electronic signature is an application of electronic signature technology, which uses image processing technology to transform electronic signature operation into the same visual effect as paper document stamping operation. Electronic signature technology is used to ensure the authenticity and integrity of electronic documents and the non-repudiation of signers.

Valid electronic signature (source: electronic signature)

Electronic signature adds the appearance of seal image on the basis of electronic signature technology, and follows the traditional visual effect of seal that people are used to. Generally speaking, electronic signature includes two forms: signature and seal. Before the original text is digitally signed, the signer's seal (signature) appearance is used and attached to the original text to form a new signed original text, and then the hash operation and digital signature are carried out to realize the electronic signature with the appearance of electronic signature.

Above, electronic signature is an application of electronic signature technology, including signature and stamp. Digital certificate, as a "network ID card", shows the real identity information of the signer and endows the electronic signature and electronic signature with authenticity and legitimacy.