Many papers died before the author died. However, some papers will be read and quoted until they become a part of our lives. In this case, they will live forever. Claude elwood shannon died on Saturday, February 24th, 2006 at the Courtyard Care Center in Medford, Massachusetts. He is 84 years old. Although he has passed away from this world, I believe that this classic paper "Communication Theory of Secure Systems" will not.

Symmetric key cryptosystem uses the same key to encrypt and decrypt messages, although a message or a group of messages may use different keys. A significant disadvantage of symmetric ciphers is that key management is required to use them safely. Ideally, each pair of different communication parties must share a different key, and may also share each ciphertext exchanged. The number of required keys increases with the square of the number of network members, which quickly requires complex key management schemes to maintain their integrity and confidentiality. When there is no secure channel between two communication parties, the difficulty of establishing a secret key between the two communication parties also raises the problem of chicken and egg, which is a considerable practical obstacle for cryptographers in the real world.

Many documents died before the author died. However, some papers will be read and mentioned until they become a part of our daily life. In this respect, they are immortal. Claude? Elwood. On February 24th, 2006, many people died in the courtyard nursing center in Medford, Massachusetts. He is 84 years old. Although he has passed away, I believe that this classic document "Communication Security System Theory" will not.

Symmetric key encryption uses the same key to encrypt and decrypt messages, but messages or group information may have different keys higher than other information. A significant disadvantage of symmetric encryption key management is that security must be used. For each different communication party, it must be ideal and have different keys, and perhaps the same is true for each ciphertext exchange. The number of keys needs to increase the number of square network members, which requires very fast and complicated key management methods to make them all straight and secret. When there is no secure channel between parties, the difficulty of establishing secure keys for communication between parties also introduces the problem of chicken and egg, which is a great practical obstacle to encrypt users in the real world.