Symmetric cryptography

Cryptography:- 

We can divided all the cryptography algorithms(ciphers) into three groups:

1. Symmetric cryptography
2. Asymmetric cryptography
3. Hash Function

Symmetric cryptography:-

          In symmetric-key cryptography, the same key is used by both parties. The sender uses this key and an encryption algorithm to encrypt data; the receiver uses the same key and the corresponding decryption algorithm to decrypt the data.

 A symmetric encryption scheme has five ingredients:

• Plaintext:  This is the original intelligible message or data that is fed into the algorithm as input.

• Encryption algorithm: The encryption algorithm performs various substitutions and transformations on the plaintext.

• Secret key: The secret key is also input to the encryption algorithm. The key is a value independent of the plaintext and of the algorithm. 

• Ciphertext: This is the scrambled message produced as output. It depends on the plaintext and the secret key. For a given message, two different keys will produce two different ciphertexts. The ciphertext is an apparently random stream of data and, as it stands, is unintelligible.

• Decryption algorithm: This is essentially the encryption algorithm run in reverse. It takes the ciphertext and the secret key and produces the original plaintext.

Private key Cryptography:-    

        Symmetric encryption also called private-key encryption or secret-key encryption involves using the same key for encryption and decryption.