2.8 Flashcards
Cryptography
Authentication and access control
Confidentiality
Nonrepudiation
Integrity
Cryptananalysis
Cracking encryption
Cryptography keys
Added to encryption but its best to use biggest kep but sometime cant. So sometimes can hash the hashes password.. known as key stretching
There are libraries for key stretching bcrypt cypher or pbkdf2
Cryptography lightweight
Iot concepts, where crpytography uses least amount of power
Homomorphic encrpyrion
can perform
Calculations in encrypted form and saved in always encrypted form
Symmetric encryption
1 key to decrypt and same key to encrypt, shared secret key
Cant scale, like someone carrying a key cant share one person carries
Th
Asymmetric encryption
Have a public key and private key, can give to anyone share etc. only way to decrypt is with private key
So one key has one way
The key pair
Asymmetric key generator creates two separate keys one is public to be shared and private stays with us
Elliptic curve cryptography
Instead of numbers we use cirves to create keys, using smaller keys and use less storage and data.
Hashes
Message digest, a finger print, a one way trip that cant be undone can be used to store passwords
How to share keys privately
Out of band exchange, like telephone
Transit encryption like asymmetric to send symmetric
Perfect
Forward secrecy
Different encryption when keys are transfer for one session, to protect and make sure multi node travel doesnt show the same key
Steganography
Hide writing in an image, secirty through obscurity. The graphic is cover text.
Can do audio or video too
Quantum computing
Not upgrade but to add
Value, a new way to make calculations. Instead of bits we use qubits, that exist between 1 and zero and is both
Scalability is advantage
Quatum key distribution,
Sent keys in traffic with out worry cause its qubits
Stream cipher vs block kcupher
Stream, encrypt one but at a tome and store one byte at a time with symmetric encryption initialization vector is added as salt
Block, one block of encryption at a time and padding is added to make sure it fits 64 or 128 bits.
Ecb cbc ctr
Electronic codebook Simplest encryption mode once block until all blocks are encrytpted
Cypher block chaining easy to implement using Xored adds more randomization or initialization vector
Counter mode, starts with counter and encrypts and each block is encrpyted based on the counter
Blockchain
A distributed ledger for records or replicates for everyone to see, includes payment processing digital id, supply chain monitoring etc
Cryptography limitations
Speed needs to perform quick enough with the encrypt and decrypt process
Size with block cipher, bytes need
To be padded From 8 to 16 bytes if needed
Weak keys, smaller keys are weaker unless double hashed
Longevity make sure keys aren’t. Outdated
Predictability and entropy, randomization
Key reuse, can be danger but saves on resources
Resources vs security constraints
