Cryptography & Network security

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What are symmetric cipher models for cryptography and network security?

scasc

Haha - There must be a reason for all the questions? Part of a project or studying for a cert/exam? . Either way, happy to help. 

Symmetric ciphers can be split into 2 types - block and stream. Block is normally used even though streams are faster and have less complexity. Types of Symmetric ciphers include DES/AES/Two-Fish/Blowfish/CAST/RC4. 

Cloudflare have written an excellent article around this - and issues with CBC mode utilized with AES. With block ciphers you split up what you want to encrypt in fixed block sizes and if needed add padding to append the end if the message does not fill out the block (hence padding oracle attack with CBC mode). Modes of operations with AES block ciphers include ECB, CBC, OFM, CFM, GCM - where the latter is authenticated encryption where the block turns to a stream approach. This is at present the most secure method to encrypt data using AES - GCM mode.

https://blog.cloudflare.com/padding-oracles-and-the-decline-of-cbc-mode-ciphersuites/

Symmetric ciphers do the bulk encryption of your data/messages whilst the asymmetric format (due to intensity in processing) will be used to exchange/send the session keys to the recipient. 

Hope this helps in some way.