## Understanding Symmetric cryptography

To understand cyber security and cryptography we will continue further today. In the previous chapter, we discussed the basics elements.

Also In 1960-70 computers started getting popular in industry and offices. Initially, security and encryption were a concern for govt offices only.

In addition to In 1973 IBM developed the Fiestal cipher. in 1949 an American cryptographer Claude Shanon introduced the substitution and permutation method of cryptography.

Another Method of Cryptography came into the picture as well. “Confusion and Diffusion” was that new cryptography method.

### Confusion and Diffusion

Also Hiding any relationship between the plain text, ciphertext, and the key is termed **Confusion**. You can not determine plain text if do not have the key. Here, in the Confusion method, the plain text is changed to

a form where it is hard to find a relation between plaintext and the ciphertext.

For example, in the Ceaser Cipher method, the original character is related by the next third character.

So Diffusion is a rearrangement of letters of plaintext.Mix utilization of Confusion and Diffusion is termed **Product Cipher**.

## Key Ingredients

Five key ingredients are primarily important.

- Sender- The user willing to send message in a seucred way.
- Enrpytion Alogrithm- The metohd which covert palintext to cryptotext format.
- Cryptotext- The form of encypted message transferred.
- Decyption Algorithm – The decrypted message converted back to plain text using shared key.
- Reciever- The trageted use for whome this message meant to send.

### Modern elements of Symmetric Alogrithm

- Data Encryption Standards (DES).
- Internation Data Encryption Algorithm (IDEA)
- Advanced Encryption Standard (AES)

Above are the standards we use today to encrypt data.

So Symmetric encryption uses a single shared key to encrypt and decrypt data. Providing fast and efficient encryption between sender and receiver.

## What is DES

In 1973, The National Institute of Standard Technology NIST issued a public request. Where they demanded the encryption algorithm. Expected to meet few criteria like:

- Easy to understand.
- Hight level of Security.
- Adoptable and economical.
- Efficient and exportable.

So In response to this **IBM** submitted **Lucifer** in 1974. Lucifer was evaluated by National Security Agency. **NSA** reduced the key length from 128 bits to 56 bits.

This Lucifer then became **DES** in 1977 as the government standard for cyber security and data encryption. DES is also known as the Data Encryption algorithm or** DEA.**

Also Primarily security of Symmetric cryptography is based on two components;

- Algorithm.
- Lenght of the key.

With a 168-bit key size, the 3DES was introduced.

Though, few other Symmetric cryptographic methods also introduced. Blowfish used by OpenBSD.

## What is IDEA

Also IDEA or international data encryption algorithm developed to replace DES.It used a 128-bit key. IDEA is patented and required a commercial license to use. In 1991, it was described first time by James Messey and Xuejia Lai.

## Understanding Asymmetric cryptography

asymmetric key encryption is also known as public-key encryption. It uses two keys that are mathematically related.

A public key that you publish and share and a private key that keep private. Let’s understand by an example.

Also If Alice wants to send a message to Bob, she will use Bob’s public key to encrypted data.Now, Bob will use his private key to decrypt secret messages back to plain text.

In addition to the comparison to the Symmetric method, Asymmetric encryption required 10000 times more computation.Which may take huge processing and time.The key pair encryption is highly secure and harder to crack.

Let’s understand by an example by using pretty good privacy encryption or PGP. Click PGP Encryption Tool – iGolder.

Click on the key generator.

So Provide an email id, assign a password and generate the key.

So Copy and paste your public and private key to some text files.

Also click to decrypt message > paste public key > type desired secret message > Encrypt meaage > Copy encrypted message.

So Let’s decrypted that message now. Click to decrypt > Paster your private key > Provide password generated in the first step > paste decrypted text copied in the previous step > Decrypt message. You can see your original text in plain text here.

**Conclusion**

This is how public and private encryption works. In the next article, we will try to touch some another interesting topic related to Encryption and security. Have a great day and stay tuned.