The main tasks of cryptography


Cryptography is not only a method to provide information security, but also a collection of mathematical techniques. There is no doubt that cryptography mainly deals with information security, but in general, in many aspects of information security, cryptography mainly provides the following protection for digital information in storage and transmission.


It is a kind of security attribute that allows specific users to access and read information, but not authorized users to understand the information content. In cryptography, the confidentiality of information is realized by encryption technology.

Data integrity

Data integrity is used to ensure that the data in the process of storage and transmission is not modified by unauthorized security attributes. In order to provide this information security attribute, users must have the ability to detect unauthorized modifications. Unauthorized modification includes data tampering, deletion, insertion and replay. Cryptography can protect the integrity of data by means of data encryption, message authentication or digital signature.


Authentication service includes authentication of identity and authentication of data source. For a communication, we must be sure that the opposite end of the communication is the expected entity, which involves identification. For data, we still want each data unit to be sent to or from the expected entity, which is data source identification. Data source authentication implicitly provides data integrity services. Cryptography can provide this authenticity service through data encryption, digital signature or authentication protocol.

Non repudiation

This is a complete feature used to prevent the communication entity from denying the previous communication behavior and related content. Cryptography provides this service through symmetric encryption or asymmetric encryption, digital signature and other technologies, and with the help of trusted institutions or certificate authorities.

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