Network Security(Symmetric Ciphers)
- 1. NETWORK SECURITY NAME OF THE STAFF : Mrs. M. FLORANCE DYANA NAME OF THE STUDENT : S.MAREESWARI, J.GAYATHRI DEVI, R.KAVITHA. REGISTER NUMBER : CB17S 250393 CB17S 250370 CB17S 250383 SUBJECT CODE : P8MCA27 CLASS : III BCA-A BATCH : 2017-2020 YEAR : 2019-2020
- 3. Introduction Block ciphers The feistel for block ciphers Data encryption standards(DES) Public key cryptography RSA encryption
- 4. Introduction Symmetric ciphers use symmetric algorithms to encrypt and decrypt data. These ciphers are used in symmetric key cryptography. A symmetric algorithm uses the same key to encrypt data as it does to decrypt data.
- 5. Symmetric ciphers are the opposite of symmetric ciphers, like those used in public-key cryptography. These ciphers use asymmetric algorithm which use one key to encrypt data and a different key to decrypt ciphers. For example, A symmetric algorithm will use key K to encrypt some plain text information like a ciphertext.
- 6. Block ciphers Block ciphers is one in which the plaintext is divided in blocks and one block is encrypted at one time producing a ciphertext of equal length Similar to substitution ciphers on very big characters: 64 bits or 128 bits are typical block lengths. Many modern ciphers are block ciphers.
- 7. The feistel structure for block ciphers The DES algorithm for encryption and decryption , which is the main theme of this lecture, is based on what is known as the Feistel structure. Named after the IBM cryptographer Horst Feistel structure and first implemented in the Lucifer by Horst Feistel and Don Coppersmith.
- 8. Data encryption standards(DES) DES is a symmetric system that was once a predominant standards in the 1970s but has since fallen our of favour due to its low security. Its introduction sparked heated debate about the role of standards in cryptography and led to much research and innovation in the field.
- 9. DES use block ciphers. The block ciphers in DES consists of 56 random bits, and 8 more bits are used for error detection. These error detecting bits makes DES unmalleable-attacks can’t change the ciphers on its way to its destination because they might accidentally delete a bit used for error detection, and then receivers would known the data had been attacked.
- 10. public-key cryptography Public –key cryptography refers to a class of cryptographic system in which each actor uses two keys: public key , private key The guiding principle is that messages Intended for a specific person should be encrypted using their public key in such a wat that the message can be only be decrypted through the use of the corresponding private key.
- 11. Public-key cryptography is important for securely transmitting messages across a potentially insecure channel, meaning that it is assumed all communications can be read by a malicious attacker. As such, public-key cryptography is especially important for ensuring the security of the internet.
- 12. RSA Encryption RSA encryption algorithm, used to securely transmit message over the internet. It is based on the principle that it is easy to multiply large numbers, but factoring large number is very difficult.