Sunday, 5 August 2018

[Tips] Private Key Encryption - Symmetric Key Encryption

Hello everybody, today my topic is Private Key Encryption

What is private key encryption?

- Data is encrypted using a single SAME key that only the sender and the receiver know. That is why private key encryption is also called symmetric key (đối xứng) encryption.
- Because the same key is used during both the encryption and decryption of the data

Here is example:

Private Key Encryption - Symmetric Key Encryption

We have two method for private key encryption:
1. Stream ciphers
2. Block ciphers

- Stream cipher works on  a single bit at a time. It encrypts data on the fly, bit by bit. This method is not much used in modern cryptography. You can see RC4 (Rivest Cipher 4) is the most widely used of all stream ciphers, particularly in software.

Stream ciphers

- A block cipher is an algorithm operating on fixed-length groups of bits. called blocks. Its encrypts data in certain length, not bit by bit. When data comes in, data comes in chunks. The usual size of each block are 64 bits, 128 bits, and 256 bits.
Some notable block ciphers include:
1. DES (Data Encryption Standard).
2. Triple DES
3. IDEA (International Data Encryption Algorithm)
4. RC5 (Rivest Cipher 5)
5. AES (Advanced Encryption Standard)
6. Blowfish

Block ciphers

The disadvantage of Private key encryption:

- The private key algorithm is simple encryption method because parties use one same single key. 
- The biggest problem with private key encryption is that you need to have a way to get the key to the party with whom you are sharing data.
- If someone gets their hands on the key, they can decrypt everything encrypted with that key!

Any questions leave your comment, we can discuss about it!

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