**What type of key cryptography, the sender and the receiver of a message share a single common key?**

**Symmetric key cryptography**

As its name implies, symmetric-key cryptography, symmetric keys are used for both encryption and decryption purposes. That means the key which is used for the decryption is the same as the key for its encryption. For this reason, this type of key cryptography can be called with another name, symmetric encryption.

Where in asymmetric key encryption, it is just the opposite of symmetric key cryptography. That is, the key which is used for the decryption of an encrypted message is different from the key which is used for the encryption of that message.

By doing this process, that is when a message is encrypted with a secret key, then that message is converted to another format, where, it cannot be read or accessed by anyone other than who having that secret key which is used for the encryption of that message. In Symmetric key cryptography, anyone can read the encrypted message if he or she having the secret key used for the encryption. But, in the case of asymmetric key encryption, the one who must know the decryption key other than the encryption key to decrypt it, because, both keys are different.

In this method, a random number generator is used for the creation of the secret key. And the success of this method relies on the strength of this key generator.

The major application area of this symmetric key cryptography is today’s internet. There are two kinds of algorithms that are used in this cryptography are,

- Block
- Stream

Some of the common algorithms which are used in symmetric key encryption are the following:

- DES(Data Encryption Standard).
- 3DES(Triple Data Encryption Standard).
- AES(Advanced Encryption Standard).

This type of cryptography needs to share the key between the sender and the receiver for encryption and decryption. Thus, these methods need to use some protocols for this purpose. Some of them are as follows:

- RSA(Rivest-Shamir-Adleman)
- DH(Diffie-Hellman)
- EC(Elliptic Curve)

Since it needs the secret key by the receiver and the sender, this symmetric key cryptography method is much faster, efficient than the other type of encryption, asymmetric key cryptography. So this method is widely used in such cases where we want to send a large amount of data.

**Also Read:**

**Static Routing and Dynamic Routing****What is Asymmetric Encryption, Cyphertext****What is DMZ (Demilitarized Zone) ?**

We can have look at the working of asymmetric key cryptography: One needs to send a message to another one, which should not read by anyone else other than the correct receiver.

So the message to send, referred to as original text, is encrypted by using the symmetric key and makes the original text into an unreadable form called the cipher text. And at the receiver side, he or she needs the same key which is used for the encryption of the message by the sender to decrypt it and makes the cipher text back into the original text.

**Advantages of symmetric key encryption:**

- Relatively fast.
- Extremely secure.

**Disadvantages of symmetric key encryption:**

- Sharing of the key.
- If the encryption key got by one, he may get a chance to decrypt other messages which use the same key.