Cryptography
Overview of this blog?
This is written to get knowledge about Cryptography, Characteristic of cipher, Cryptographic Terminology, Encryption , Decryption, Symmetric and Asymmetric Encryption.
Cryptography Is Art of Secret Writing.
Cryptoanalysis is Art Of Converting the cipher text to plain text without using the secret key.
Cryptology include both cryptography and cryptoanalysis.
Characteristics of a good cipher
Confusion
Interceptor should not be able to predict how changing one character in plaintext will change the ciphertext.
Diffusion
The Characteristic of distributing the plaintext over the entire ciphertext.
Stream Cipher
Pros : Fast , Low Error Propagation
Cons : Less Diffusion , Susceptible to malicious inserts and modifications.
Block Cipher
Pros : Diffusion , Immunity to insertion
Cons : Error propagation , Slow
Unconditional Security
Cipher can’t be broken irrespective of the Computational Power / time available.
Computational Security
Cipher can be broken using a brute force attack. (Take a very Long Time)
Cryptographic Terminology
Plain text: the message before encryption.
Cipher text: the message after encryption.
Key: information needed to convert from plain text to cipher text (or vice-versa).
Function/cipher: the encryption or decryption algorithm used, in conjunction with key, to encrypt or decrypt message.
Key distribution: How to distribute keys between senders and receivers.
Encryption and Decryption
Symmetric Encryption and Asymmetric Encryption
Conclusion
You can get some basic knowledge about Cryptography. Mainly these essential points are discussed here.
