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Shadow Cipher

Pelcgbytbtl(Cryptography)

Cryptography

  • Encryption
    The act of taking a message, called plaintext, and applting an opeation to it, called a cipher, so that you receive a garbled, unreadable message as the output, called ciphertext.

  • Decryption

  • Holly Wyrld

  • key

  • Encryption algorithm
    The underlying logic of process that’s used to convert the plaintext into ciphertext

  • Security through obscurity

  • Kerchoff’s principle

  • Cryptosystem
    A collection of algorithms for key generation and encryption and decryption operations that comprise a cryptography service should remain secure - even if everything about the system is known, except the key

  • Shannon’s maxim
    The system should remain secure even if your adversary knows exactly what kind of encryption systems you’re employing, as long as your keys remain secure.

  • Cryptology

  • Cryptoanalysis

  • Frequency analysis
    The practice of stuying the frequency with letters appear in a ciphertext

  • e t a o

  • th er on an

  • Stenography
    The practice of hiding information from observers, but not encoding it

Symmetric Cryptography

  • Symmetric-key algorithm

  • Substition cipher
    An encryption mechanism that replaces parts of your plaintext with ciphertext

  • Caesar Cipher

  • Stream cipher
    Takes a stream of input and encrypts the stream one character or one digits at a time, outputting one encrypted character or digit at a time.

  • Block ciphers
    The picker takes data in, places it into a bucket or block of data that’s fixed size, then encodes that entire block as one unit.

  • Initialization vector

Symmetric Encryption Algorithms

  • SData Encryption Standard

  • FIPS
    Federal Information Processing standard

  • Key length

  • Brute-force attack

  • 2 

    56

  • National Institute of standards & technology

  • Advanced Encryption Standard

  • Because of large key size, brute-force attacks on AES are only theoritical right now, because the computing power required(or time required using moderm technology) exceeds anything feasible today.

  • An important thing to keep in mind when considering various encrytpion algorithms is speed and ease of implementation.

  • RC4 (Rivest Cipher 4)
    A symmtric stram cipher that gained widespread adoption because of its simplicity and speed

  • TLS 1.2 with AES GCM

Asymmetric Cryptography

  • Asymmetric or public key ciphers

  • Public key signatures

  • Confidetiality

  • Authenticity

  • Non-repudiation

  • Message Authentication Codes(MACs)

  • MAC
    A bit of information that allows authentication of a received message, ensuring that he message came from the alleged sender and not a third party

  • HMAC
    Key-hash message authentication code

  • CMACs Cipher-Based Message Authentication Codes

  • CBC-MAC
    Cipher block chaining messge authentication codes

Asymmetic Encryption Algorithms (RSA)

  • Digital Signature Algorithm

  • Diffie-Hellman

  • Elliptic curve crytography(ECC)
    A public-key encryption system that uses the algrebic structures of elliptic curves over finite fields to generfate secure keys

  • Both Diffie-Hellmen and DSA have elliptic curve variants, referred to as ECDH and ECDSA, respectively.