- periodic (repeatable sets)
- fast
- deterministic (predictable sets)
Pseudo-Random Number Generators (PRNGs)
- aperiodic
- slow
- Non-deterministic
True Random Number Generators (TRNGs)
8-bit values, up to 256 characters
ASCII
16- bit values, up to 65,536 characters
UTF-16
Secret Key encryption is needed for…
symmetric cryptography; makes use of a single secret key for both encryption and decryption.
What specific algorithm is used in asymmetric cryptography overcome the weakness of symmetric cryptography through secret key encryption?
Diffie-Hellman is a widely used key exchange algorithm used to exchange the secret key in symmetric cryptography.
Aescrypt
encrypts individual files
Bitlocker
encrypts full disks
FileVault
encrypts full disks
Pseudo-Random Number Generators (PRNGs)
- periodic repeats the random numbers after a given time
* They are fast deterministic and are useful in producing a repeatable set of random numbers.
True Random Number Generators (TRNGs)
•This method generates a true random number and uses some form of random
process.
•Overall, the method is generally slow, but is non-deterministic and aperiodic.
- Poly-alphabetic cipher
- Like multiple Caesars
- based on a keyword
- difficult to guess
Vigenere
- Encrypts two letters instead of one, this makes it more complex.
- 5x5 table
- based on a keyword and rule set
- Removes repeating letters
Playfair
- Mono-alphabetic substitution cipher
- maps plaintext characters to symbols rather than to letters
- 2 square grids, 2 X-shaped grids, dots.
- Easy to remember
Pigpen
- Makes use of a grid
* maps the letters into numeric values.
BIFID
- Transposition cipher
- encrypts the message by altering each letter on a different row
- message must then be written down left to right and put into rows
Rail Fence (Zig-Zag)
- mitigates frequency analysis
- mono-alphabetic
- mappings depend number of occurrences for a letter
homophonic substitution code
- Can optionally use four 5x5 matrices arranged in square
- 25 letters
- bigrams.
- Maps to numbers
Four-square Cipher
extension of BIFID?
- poly-alphabetic
- substitution cipher
- secret key
- letters could not be ciphered as itself.
Enigma Machine
- substitution cipher
- maps letters to numbers
- Uses mod math algorithm
Affine Cipher
- transposition cipher
- 36 letter alphabet
- Polybius square
- single columnar
ADFVGX Cipher
- poly-Alphabet
* Turning produced different ciphertexts.
Cipher Disk
Examples of poly-alphabetic ciphers
Vigenere
Cipher disk
Enigma machine
