9-9-2024

Steganography

• Hiding the existence of data
• Images, audio or video files can contain hidden messages imbedded in the file
• Dividing data and hiding in unused portions of file
• Often hidden in data header between sections of metadata

Cryptography

• Scrambling data so that it may be read by only the sender and receiver (in theory)
• Plaintext - unencrypted data
• Ciphertext - scrambled unreadable data
• Cleartext - unencrypted data that is not intended to be encrypted
• Key - mathematical value placed into the algorithm to produce cyphertext

Benefits of cryptography

• Confidentiality - makes sure only authorized parties can view
• Integrity - ensures info is correct and unchanged
• Authentication - ensures sender can be verified through cryptography
• Nonrepudiation - proves that a user performed and action
• Obfuscation - making something obscure or unclear
• Security through obscurity - an approach where virtually any system can be made secure as long as outsiders never know about it or what it is

Cryptographic algorithms

• Hash
• Symmetric cryptographic
• Asymmetric cryptographic

Variations of algorithms

• OTP(one time pad) combines plaintext with a randomized key
• A pad is a long sequence of random letters
• In order to decipher, recipient must have a copy of the pad
• Stream cipher - takes one char and replaces with another
• Block cipher - manipulates an entire block of plaintext at once
• Sponge function - takes a string of any length as input and returns a string of any requested variable length

Hash algorithms

• A unique "digital fingerprint" of a set of data
• Represents contents of a message
• Primarily used for comparison purposes
• Intended to be one way that its digest cannot be reversed to reveal original data set
• Considered secure if it has a fixed size, is unique, is original, and is secure (cannot be reversed to determine plaintext)
• SHA (Secure Hash Algorithm)
• RipeMD
• Whirlpool

Symmetric cryptographic algorithm

• Use same key to encrypt and decrypt data
• Also called private key cryptography
• Key is kept private between sender/receiver
• Can provide strong encryption if key is kept secure
• AES (Advanced Encryption Standard)
• Blowfish and Twofish