D334 Intro to Cryptography

D334 Intro to Cryptography (1 review) Students also studied Terms in this set (53) Western Governors UniversityD 278 Save C839v5/D334 Additional Practice Teacher 165 terms ShawnD_Preview Introduction to Cryptography - D33...250 terms Square_Bubble Preview C839v5/D334 Algorithms Drill Teacher 51 terms ShawnD_Preview WGU C 293 term Wie Practice questions for this set Learn1 / 3Study using Learn • The simplest encryption mode • Too simple for most use cases • Each block is encrypted with the same key • Identical plaintext blocks create identical ciphertext blocks Choose an answer 1Mono-alphabetic substitution2ECB (Electronic Code Book) 3Combination vs. Permutation4TRNGs Don't know?

Mono-alphabetic substitutiona substitution cipher that only incorporates a single alphabet in the encryption process polyalphabetic substitutiona substitution cipher that incorporates two or more alphabets in the encryption process One-time padan example of perfect (unbreakable) encryption, which is achieved by using, only once, a random polyalphabetic key that is as long the message itself.PRNGsPseudo-random number generators. Algorithms that can greate long runs of numbers with good random properties, but eventually the sequence repeats.TRNGsTrue Random Number Generators This method generates a true random number and uses some form of random process. One approach is to monitor the movements of a mouse pointer on a screen or from the pauses between keystrokes. Overall, the method is generally slow, especially if it involves human interaction, but is non-deterministic and aperiodic.Frequency AnalysisA technique that is based on how frequently certain letters appear in English versus others.EX. a three-letter ciphered text combination spotted at the beginning of a string too often could tip us off that those three letters correlate the letters THE in the English alphabet.EntropyA measure of disorder, randomness, or unpredictability.

• common binary to characters encoding methods ASCII (8-bit values, up to 256 characters)

UTF-16 (16- bit values, up to 65,536 characters).HSM (Hardware Security Module)is a tamper-evident and intrusion-resistant physical device that safeguards and manages cryptographic keys and provides cryptographic processing.TPM (Trusted Platform Module)A trusted platform module (TPM) is a dedicated processor that handles hardware- level encryption; allows the use of full disk encryption on a hard drive in a manner that minimizes the impact on system performance. TPM contains the encryption keys.

Binary mathBasic premise is knowing what combination of binary digits will produce a binary "1". AND requires two 1's to output a 1; OR requires at least one 1 to output a 1, and with XOR, there must be a mismatch Modulus Operator MathSimply divide the first number by the second and return the remainder. Annotated using the (mod) or (%). Example: 5 mod 2 = 1 [2 goes into 5 a max of twice (4), 5-4 = the remainder which is 1]

Combination vs. Permutationcombination: order doesn't matter

permutation: order matters

set theory Modulus operator Math Early Cryptosystems Recap Diffe Hellman Key ExchangeDiffie-Hellman is a way of generating a shared secret between two people in such a way that the secret can't be seen by observing the communication. That's an

important distinction: You're not sharing information during the key exchange,

you're creating a key together.

• types of symmetric encryptionBlock and stream

Symmetric block encryption involves grouping data into blocks and encrypting the individual blocks symmetric stream encryption involves encrypting one bit at a time, i.e., a synchronous stream Common Block Cipher ModesElectronic Code Book (ECB), Cipher Block Chaining (CBC), Cipher Feedback (CFB), Output Feedback (OFB), Counter (CTR) Mode CFB, OFB, and CTR implementations essentially allow the block cipher to operate like a stream cipher.ECB (Electronic Code Book)• The simplest encryption mode • Too simple for most use cases • Each block is encrypted with the same key • Identical plaintext blocks create identical ciphertext blocks

CBC (Cipher Block Chaining)A mode of operation used for encryption that effectively converts a block cipher into a stream cipher. It uses an IV for the first block and each subsequent block is combined with the previous block.CFB (Cipher Feedback)Similar to CBC, CFB is a mode of operation for block ciphers. However, CFB encrypts and transfers plaintext values one at a time as well as employing the use of IVs and XOR functions.OFB (Output Feedback)IV with key is cipher text Cipher text of first block is IV of second block Cipher text of second block is IV of third and so on CTR (Counter Mode)Uses an incremental counter to be able to add randomization to the encryption process.S-boxes (substitution boxes)Secret key ciphers make use of substitution boxes (S-boxes) to perform substitution as part of the encryption process. Sboxes take a given input and leverage look-up tables to produce a given output.SaltingAdding random data into a one-way cryptographic hash to help protect against password cracking techniques Hashing recap Public-key encryption (asymmetric encryption) uses two keys: public key to encrypt but private key to decrypt; essential for e- commerce Public key recap