The history of symmetric encryption technology can be traced back to the last century. During World War II, cryptography was extremely important in military and politics. Password cracking and password secrecy between the Allied Forces and the Axis Powers are crucial tactics, so the research and development of encryption technology has received more attention and investment.

Symmetric encryption adopts symmetric cryptographic coding technology, which is characterized by using the same key for file encryption and decryption, that is, the encryption key can also be used as the decryption key. This method is called symmetric encryption algorithm in cryptography.

Symmetric encryption algorithm is simple and fast to use, and the key is short, so it is difficult to decipher. In addition to data encryption standard (DES), another symmetric key encryption system is International Data Encryption Algorithm (IDEA), which has better encryption than DES and does not need so many computer functions. The IDEA encryption standard is used by PGP (quite good privacy) systems.

There are several problems in symmetric encryption algorithm in e-commerce transactions;

1. It is required to provide a secure channel for both parties to communicate so that they can negotiate the same key when communicating for the first time. Direct face-to-face negotiations may be unrealistic and difficult to implement, so the two sides may need to negotiate by mail, telephone and other relatively unsafe means;

2. The number of keys is difficult to manage. Because each collaborator needs to use different keys, it is difficult to adapt to a large number of information exchanges in the open society;

3. Symmetric encryption algorithms generally cannot provide information integrity authentication. It cannot verify the identity of the sender and the receiver;

Management and distribution of symmetric keys

The management and distribution of symmetric keys is a potentially dangerous and troublesome process. Symmetric encryption is realized on the basis of confidentiality. Both parties using symmetric encryption technology must ensure that they use the same key, ensure the safety and reliability of key exchange between them, and set up procedures to prevent key leakage and change keys.