Domain 3. Sec Architecture and Engineering - Algorithms Flashcards
DES
Symmetric
64 bit cipher block size and 56 bit key
with 8 bits parity.
* 16 rounds of transposition and
substitution
(ECB, CBC, CFB, OFB, CTR)
AES
Symmetric Block cipher.
Use 3 different bit size keys 128, 192, 256
Examples Bitlocker, Microsoft EFS
Fast, secure 10,12, and 14
transformation rounds
3DES
Symmetric
DES x3, 56 bit keys not 64 bit
IDEA
Symmetric
128 bit key
64 bit cipher blocks
each block divide to 16 smaller
blocks
Each block undergo 8 rounds of
transformation
Example PGP
SkipJack
Symmetric
Uses Key Escrow
80 bit
64 bit cipher block
Blowfish
Symmetric
32 bit to 448 bit key
64 bit block cipher
TwoFish
Symmetric
128, 192, 256 bit key options
128 bit block
RC4
Symmetric Stream cipher
40-2048 key size.
Example SSL and WEP
* Stream cipher
* 256 Rounds of transformation
RC5
Symmetric Block cipher
2048 bit key
255 rounds transformation
* 32, 64 & 128 bit block sizes
CAST
Symmetric
Keys: CAST 128(40 to 128 bit)
CAST 256 (128 to 256 bit)
64 bit block 12 transformation rounds
128 bit block 48 rounds
transformation
Diffie-Hellman
Technically Asymmetric.
No confidentiality, authentication, or
non-repudiation
* Secure key transfer
RSA
Asymmetric
4096 bit key
- Public key and one-way function for
encryption and digital signature
verification - Private key and one-way function for
decryption and digital signature
generation - Used for encryption, key exchange and dig. signatures.
El-Gamal
Asymmetric
Used for encryption, key exchange
and digital signatures
* Slower
Elliptic Curve Cryptosystem
Used for encryption, key exchange
and digital signatures
* Speed and efficiency and better
security
MD5
Hash
It is one of the most popular hashing algorithms.MD5 produces a 128-bit digest. Messages are processed in 512-bit blocks, using four rounds of transformation. The resulting hash is typically represented as a 32-digit hexadecimal number. MD5 is susceptible to collision.
MD6
Hash
It uses very large input message blocks (up to 512 bytes) and produces variable-length digests (up to 512 bits).
SHA1
Hash
Published in 1995, it takes a variable size input (message) and produces a fixed-size output (160-bit message digest, versus MD5’s 128-bit message digest). SHA-1 processes messages in 512-bit blocks and adds padding to a message length, if necessary, to produce a total message length that’s a multiple of 512. This algorithm is not stable, so it is recommended not to use it.
SHA2
Hash
Published in 2001, it consists of four hash functions — SHA-224, SHA-256, SHA-384, and SHA-512 — that have digest lengths of 224, 256, 384, and 512 bits, respectively. SHA-2 processes messages in 512-bit blocks for the 224, 256, and 384 variants, and 1,024-bit blocks for SHA-512.
SHA3
Hash
Published in 2015, SHA-3 includes SHA3-224, SHA3-256, SHA3-384, and SHA3-512, which produce digests of 224, 256, 384, and 512 bits, respectively. SHAKE128 and SHAKE256 are also variants of SHA3.
Do SSL and TLS both us Asymmetric AND symmetric encryption?
Yes- Assymmetric Encryption is used to pass a shared key across, then the session shifts to symmetric encryption.
Homomorphic encryption
A unique type of encryption which supports the ability to perform computations on its encrypted data fields WITHOUT decrypting it first. When the resulting output is decrypted, it will yield accurate computational results that are identical to what would’ve been obtained if the same computations had been performed on the unencrypted data.
What is cryptographic Confusion?
Confusion is introduced using Substitution. Confusion means each bit of the ciphertext depends on multiple parts of the key. This obscures the connections between the two and decreases the likelihood it can be reversed.
Cryptographic Diffusion
Diffusion is introduced using Transposition. Diffusion means that if a single change in the plaintext occurs, multiple ciphertext changes will also occur. Transposition is the rearrangement of data.
Key Escrow
When multiple parties each have part of the key, OR when one impartial third party has the key.
Transposition cipher
Re-arranges EXISTING text to create the ciphertext.
Vulnerable to character frequency analysis.
Is a one-time pad considered a type of stream cipher?
Yes, most of the time.
CISSP Certified Information Systems Security Professional Official Study Guide, 9th Edition. Pg 234-236, 237.
A Block cipher breaks down the message into blocks of _____?
Bits. I.e. RC5 can break down encryption into 32, 64, or 128 bit blocks.
Merkle-Hellman Knapsack
Yes, this is actually an algorithm.
Now considered insecure.
Initialization vector
Picks an arbitrary point or piece of data to start the chain of encryption. Primarily used to prevent patterns from being observed in ciphertext.
Does Elliptic Curve Cryptography use prime number factoring?
No.
