Exam 3 Flashcards
Define Plain/Clear Text & Cipher text.
Plain/Clear Text – the original, unaltered data. Not always “text,” but rather, the data.
Cipher Text –data that has been converted into an encrypted form using an algorithm. Can be decrypted using an algorithm.
Know what hashes are and why they are used?
Hashing – one-way encryption that cannot be reversed (in theory) & provides assurance of data integrity.
- A hash value of a given data set will never change unless the data set changes.
Which MD algorithms are broken?
MD2, MD4, & MD5 – “MD” stands for “message digest”
What a collision attack is? what the code for this?
Collision Attacks – an attack that tries to find 2 different message data sets with the same hash.
- If 2 different data sets result in the same hash value when run through a hashing algorithm, that algorithm is broken.
Ex: hash(m1) = hash(m2)
CODE// hash (p1 | md) = ct
hash (p2 | md) = ct
What needs to be understood with Symmetric encryption?
Symmetric Cryptography – Any cryptographic algorithm that uses a single key to both ENCRYPT and DECRYPT.
Which two of the listed symmetric algorithms are broken?
3DES, Blowfish, DES, AES, RC2, RC4, RC5, RC6, IDEA
DES is broken and that RC4 (also broken) was used in WEP for home routers
Define Cipher & Key.
Cipher – the algorithm used for encrypting plain text into cipher text.
Key – a discrete piece of information, usually random in nature, that “unlocks” the cipher text.
What are the two biggest weaknesses of symmetric encryption?
Symmetric encryption lacks nonrepudiation and secure key sharing.
What are the two keys that asymmetric encryption use?
two keys: private and public
Describe how a session key is generated.
The client accepts the server public key,
generates a session key using agreed-upon algorithm, then encrypts the session key using the public key.
Between a public and private key, which is the one that can decrypt anything?
Only the private key can decrypt anything encrypted with the public key.
For RSA, know the formulas to encrypt and decrypt.
Encrypt: t^e (mod n) = c
Decrypt: c^d (mod n) = t
What are the two forms of ECC?
group addition—when there are 3 points of intersection
point doubling—when there are 2 points of intersection
In an ECC public key what does (P, T) stand for?
P in public key is the leftmost point or the first point of the intersection
T is some random point or an agreed-upon point on the curve
In an ECC private key, what does (d) stand for?
(d) is the number of group additions or point doubling to get back to T
( reflected across the x-axis until you reach T)
Why is ECC popular?
ECC is popular because it can reach the same (or higher) levels of security as RSA, but uses much shorter key lengths.
What are the two forms of VPNs?
site-to-site and remote-access
Of the 6 VPN protocol families, which are the most widely
used?
MPLS, IPsec, and SSL/TLS
MPLS doesn’t do what by itself?
MPLS does not encrypt traffic by itself
