Cryptographic Solutions Flashcards
Cryptography
Practice and study of writing and solving codes to hide the tru meaning of information
Encryption
Process of converting ordinary information (plaintext) into an unintelligible form (cyphertext)
Data States
- Data at rest
- Data in transit
- Data in use
Algorithm (Cipher)
Performs encryption and decryption
Cryptographic key
Essential piece of information that makes the algorithm secure
Symmetric vs Asymmetric Algorithms
- Symmetric algorithms use the same key for both encryption and decryption. Sometimes called Private Key
- Asymmetric algorithms use a pair of different keys for encryption and decryption. Sometimes called Public Key
Hashing
One way cryptographic function that produces a unique message digest from an input
No way to recreate the original input, allowing the hash digest to act as a digital fingerprint
PKI
Public Key Infrastructure is a framework for managing digital keys and certificates
Steganography
Hiding secret data within ordinary, non secret, files or messages, to avoid detection
Stream vs Block Cypher
- Stream Cypher encrypts data bit by bit. Utilizes a key stream generator which is XOR’d with the data to create the ciphertext. Tend to be symmetric and are good for encrypting real time data
- Block Cyphers break the data into fixed length blocks and encrypts each one. Will pad data as needed to reach the required block size
DES
Data Encryption Standard
Symmetric block cipher
Key: 64 bit (functionally 56 bit, due to parity)
Heavily used from the 70’s to 2000’s
3DES
Triple DES
Symmetric block cipher
Key: three different 56 bit keys (Encrypt, Decrypt, Encrypt). Functionally a 112 bit key
IDEA
International Data Encryption Algorithm
Symmetric block cipher (64 bit blocks)
Key: 128 bit
Not ever commonly used
AES
Advanced Encryption Standard
Symmetric block cipher (128, 192 or 256 bit blocks)
Key: 128, 192 or 256 bits (matches block size)
Chose to replace DES/3DES through a contest held by the US government. Current main standard of the US government. Most commonly used cipher and considered to be the strongest
Blowfish
Symmetric block cipher (64 bit blocks)
Key: 32-448 bits
Developed as a replacement for DES, though not widely used. Opensource
Twofish
Symmetric block cipher (128 bit blocks)
Key: 128, 192, 256 bit
Opensource
RC4
Rivest Cipher 4
Symmetric stream cipher
Key: 40-2048 bits
Used in SSL and WEP
RC5
Rivest Cipher 5
Symmetric block cipher
Key: up to 2048 bits
RC6
Rivest Cipher 6
Symmetric block cipher
Based on RC5 and entered into the contest to replace DES. Lost to AES
How does asymmetric encryption handle the need for Confidentiality?
By encrypting with the recipient’s public key, only they can decrypt, with their private key
How does asymmetric encryption handle the need for non-repudiation?
By encrypting with the sender’s private key, anyone can decrypt it with their public key, validating the sender
How does asymmetric encryption handle the need for Integrity?
By creating a hash digest of the message which is then encrypted with the sender’s private key (this is a digital signature).
Then you encrypt the message with the receiver’s public key.
This ensures Confidentiality, Integrity and Non0-repudiation
DH
Diffie-Hellman
Key Exchange Algorithm
Often used for sharing private (symmetric) keys, such as for VPN tunnels for IPSec
RSA
Rivest, Shamair & Adleman
Asymmetric encryption algorithm
Supports key sizes from 1024 to 4096 bits
Relies on the difficulty of factoring large prime numbers
Often used for MFA fobs
