2.8 cryptographic concepts Flashcards
ciphertext
encrypted message
cipher
algorithm to encrypt/decrypt
cryptanalysis
art of encryption cracking
homomorphic encryption
a cryptographic technique that allows computations to be performed on encrypted data without requiring decryption
symmetric encryption
a technique that uses a single key to encrypt and decrypt data
- does not scale well
- very fast to implement
asymmetric encryption
two key system
Public key: Used for encryption
Private key: Used for decryption
Elliptic Curve Cryptography
asymmetric encryption uses curves instead of numbers
Hash Collision
when two different pieces of data produce the same hash value
key exchange
a cryptographic process that allows two parties to exchange keys. This allows them to use the keys to share encrypted information.
Perfect Forward Secrecy
Perfect Forward Secrecy
a type of encryption that automatically and frequently changes the keys used to encrypt and decrypt information.
SSL/TLS feature
more computing power and must be supported by browser
steganography
the practice of concealing information within another message or physical object to avoid detection
message is invisible
- hide message in TCP packets
- embed in image
- invisible watermarks
- audio
- video
cipher stream
one byte at a time
high speed, low hardware
symmetric encryption
cipher block
encrypts a block of bytes at one time
64-128 bits
symmetric encryption
CBC
cipher block chaining
add randomization via IV
initialization vector (IV)
This is a block of bits that randomizes the encryption. It produces distinct ciphertexts even if the same plaintext is encrypted multiple times.
XOR
eXclusive OR
adds randomization
symmetric encryption
crypto use cases
- Low power devices
- Low latency
- High resiliency
- Supporting confidentiality
- Supporting integrity
- Supporting obfuscation
- Supporting authentication
- Supporting non-repudiation
crypto limitations
- Speed
- Size
- Weak keys
- Time
- Longevity
- Predictability
- Reuse
- Entropy
- Computational overheads
- Resource vs. security constraints
symmetric key creation
use a public and private key to create a symmetric key
PFS
perfect forward secrecy
an encryption system that automatically and frequently changes the keys used to encrypt and decrypt information.
ephemeral
involves the use of cryptographic keys that are generated for each execution of a key establishment process. These keys are also known as session keys.
AE
Authenticated Encryption
specialized block cipher modes of operation
lightweight cryptography
a type of encryption that’s designed for devices with limited resources such as IoT.
