In fact, digital signature is to extract the data digest (hash value) from the data through the hash algorithm, encrypt the data digest with the private key in the asymmetric key to prevent the digest from being cracked and tampered in the transmission process, decrypt the digest with the public key after receiving it, and then extract another data digest from the data, and compare the two abstracts. The abstracts are the same, indicating whether the data has been tampered with. Digital signature is generally used to publish data in clear text, which can be read by everyone (such as software packages, official documents, etc. ), but they are worried about being tampered with during transmission (such as adding Trojan virus, etc.). ), so digital signature is needed, and its main function is to ensure the integrity of data and the confidentiality of data abstract.
It can be better understood with this schematic diagram. /Basic/images/codesign _ Basic . gif