Digital signature is an important tool to realize identity authentication, which can ensure the authenticity of electronic documents or messages in digital communication and provide proof of original and unmodified documents by using encryption technology. One of the functions of digital signature is to replace the traditional manual signature and stamp in the network environment.

Advantages of digital signature:

1, anti-counterfeiting (forgery)

Only the signer knows the private key, so it is impossible for others to construct it correctly.

2, can identify the identity

Because the traditional manual signature is usually a direct meeting between the two parties, the identity can be clear. In the network environment, the receiver must be able to identify the identity claimed by the sender.

3. Tampering (preventing the integrity of information from being destroyed)

For the traditional manual signature, if you want to sign a 200-page contract, do you just sign at the end of the contract? Or sign every page? If you only sign at the end of the contract, will the other party steal a few pages? For digital signature, the signature and the original file have formed a mixed whole data, which can not be tampered with, thus ensuring the integrity of the data.

4. Anti-replay

For example, in daily life, A borrows money from B and writes an IOU to B. When A pays back the money, he must ask B for the IOU he wrote and tear it up. Otherwise, I'm afraid he'll have to ask A for money again with an iou. In digital signature, if the technology of adding serial number and timestamp to the signature message is adopted, replay attack can be prevented.

Step 5 refuse to prevent

Digital signature can identify identity, and it is impossible to pretend to be forged. Then, as long as the signed message is retained, it is like retaining the handwritten contract text, that is, retaining the evidence, and the signer cannot deny it. What if the receiver did receive the other party's signature message, but denied it? To prevent the recipient's denial. In digital signature system, the receiver is required to return the message with his own signature to another party or a third party, or introduce a third party mechanism. In this way, neither side can deny it.

6. Confidentiality (confidentiality)

Handwritten documents (like text) are not confidential, and once the document is lost, the information in it is likely to be leaked. Digital signature can encrypt the hash value of the message to be signed, but it is not necessary to encrypt the message itself. Of course, if the signature registration does not need confidentiality, it does not need encryption.

7. Ensure the integrity of information transmission, the identity authentication of the sender, and prevent denial in the transaction.

Digital signature technology encrypts abstract information with the sender's private key and sends it to the receiver together with the original text. The receiver decrypts the encrypted digest information with his own public key, and then generates the digest information for the received original text with a hash function, and compares it with the decrypted digest information. If they are the same, it means that the received information is complete and has not been modified during transmission, otherwise it means that the information has been modified, so the digital signature can verify the integrity of the information.

Digital signature is an encryption process and digital signature verification is a decryption process.

Knowledge expansion

What does digital signature mean?

Digital signature, also known as public key digital signature, is a kind of digital string that can only be generated by the sender of information and cannot be forged by others. This number string is also an effective proof of the authenticity of the information sent by the information sender. It is a method to authenticate digital information, which is similar to the ordinary physical signature written on paper, but it is realized by using the technology in the field of public key encryption. A set of digital signatures usually defines two complementary operations, one for signing and the other for verification. Digital signature is the application of asymmetric key encryption technology and digital digest technology.