3.2 Cryptography Flashcards
Cryptography protects _________ and _____ of data in daily transactions. Where is it used? 3 things -
confidentiality; integrity.
It’s used in cell phones, email, online shopping, etc.
Caesar cipher does what? It’s a classic _________ cipher.
shifts alphabet letters, typically by 3 spaces.
-substitution
What is the difference between a block and a stream cipher?
block encrypts chunks of data at at a time. can render large portions unusable.
stream encrypts bit by bit. better for files of variable lengths, like streaming video where size can change.
ECC is classified as which type of cryptographic algorithm?
single algorithm; fast and efficient - uses less process power and memory, good for cell phones or portables. Uses short keys while maintaining higher strength. Asymmetrical Key Algorithm.
What is the key point of Kerckhoffs’s second principle?
“The system must not require secrecy; even if stolen by the enemy, system should remain secure.” Remains a key tenet of modern crypto algorithms. System should be robust so if people know all of the encrpytion process except for the key, they shouldn’t be able to break.
What is a substitution cipher?
Substitutes each letter in the alphabet with another one.
What are the main differences between symmetric and asymmetric key cryptography?
symmetric uses single key for encryption and decryption. Sender and receiver have the same key. Much more efficient at encrypting large amounts of data than asymmetric.
How does public key cryptography work?
Public key cryptography, or asymmetric cryptography, uses a pair of keys: a public key, which can be shared, and a private key, which must be kept secret.
- Key Generation: Each user creates a public-private key pair.
- Encryption: A sender encrypts a message using the recipient’s public key, ensuring only the recipient can decrypt it with their private key.
- Decryption: The recipient uses their private key to decrypt the message.
- Digital Signatures: A sender can sign a message with their private key, allowing others to verify it with their public key, ensuring authenticity.
- Key Exchange: It facilitates secure key exchange over insecure channels.
The security relies on the difficulty of specific mathematical problems, making it hard for attackers to deduce the private key from the public key.
Explain how 3DES differs from DES.
-DES used back into the 1970
s - have been comprimised.
-3 DES encrypted DES 3 times.= however it consumed a lot of processor power and memory and was replaced by AES.
Try to decrypt this message using the information in this chapter: V qb abg srne pbzchgref. V srne gur ynpx bs gurz. —Vfnnp Nfvzbi.
I do not fear computers. I fear of
How is physical security important when discussing the cryptographic security of data?
Protects security at rest and is a layer of defense. Also in motion as a thumb drive can be stolen and exploited.
Core Features of Cryptography are? 4-
o Confidentiality: Prevents unauthorized disclosure of data
o Integrity: Ensure data isn’t modified
o Authentication: Used to validate sender with digital signatures
o Non-repudiation: Digital signatures also ensure non-repudiation
What is Plain Text
o An unencrypted message
- Cipher Text
o An encrypted message
What is Cipher
o The encryption algorithm used to encrypt & decrypt the message
What is Key?
Determines the output of the cipher algorithm and is needed to encrypt and
decrypt a message
What are some downfalls of symmetric (private key Encrytion)
-The downside of symmetrical encryption is that it makes it hard to initiate communication
the first time. (exchanging them)
- If attacker gets hold of key, they can open any encrypted email you’ve sent. (storing them)
-The SAME Key is used for both encryption and decryption.
What is the Official Encryption standard of the U.S. Federal Government?
AES - Advanced Encryption Standard
How long to break a 128-Bit AES by brute force?
Billions of Years
_________ encryption uses two keys, a ________and a ______ created as a matched pair.
- Asymmetric encryption uses two keys, a public key and a private key created
as a matched pair.
o Private Key: Kept secret and never shared.
o Public Key: Shared with others.
What is Asymmetric (public key) Encryption also know as?
Commonly referred to as:
o Public Key Encryption
o Public Key Infrastructure (PKI) Encryption
What does Public Key Encrption(Asymmetric) Provide when sending using a private key?
Confidentiality - NO, because he is possibly sharing his public key with many people.
1- Authentication - only one who could encrypt is bob
2- Non-repudiation -
3- Integrity - (if used with hashng)
When receiving a public key encryption (a reply) back from a person what is provided?
What part of the CIA triad?
Confidentiality - because once encrypted, only person who can open it is Bob, the original encryptor
Describe “security through obscurity”. What is the opposite of it?
a devices strength was that the equipment and settings were secret for specific messages. example, Enigma. -
Opposite is Kerckhoffs second principle “….system shouldn’t require secrecy”
