1, authentication
Public key encryption system allows anyone to encrypt information with public key when sending information and decrypt information with private key when receiving information. Of course, the receiver can't be 100% sure of the real identity of the sender, only if the password system is not attacked and translated.
The importance of authentication is particularly prominent in financial data. For example, suppose a bank sends instructions from its branches to its central management system. The format of the instruction is (a, b), where a is the account number of the account and b is the current amount of the account. At this time, the remote client can deposit money first, observe the results of transmission, and then send instructions in (a, b) format one after another. This method is called replay attack.
2. Data integrity
Data integrity refers to the process of transmitting and storing information or data, ensuring that information or data can be found quickly without being tampered with or tampered with.
Both sides of data transmission always want to confirm that the message has not been modified during transmission. Encryption makes it very difficult for the third party to read the data, but the third party can still use feasible methods to modify the data during transmission.
A popular example is the same type of attack: in retrospect, it is the same bank that sends instructions in the format of (A, B) from its branches to its central management system, where A is the account number and B is the amount in the account. A remote customer can save money first, then intercept the transmission result and transmit it (A, B), so that he becomes a millionaire immediately.
3. Undeniability
In the context of ciphertext, the word "denial" refers to Naijian's denial of actions related to the message (that is, claiming that the message comes from a third party). The receiver of the message can prevent all subsequent denials by digital signature, because the receiver can show the signature to others to prove the source of the information.