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CompTIA Security+ Study Guide by Mike Chapple > Chapter 7 > Flashcards

Chapter 7 Flashcards

Cryptography and the PKI (65 cards)

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1
Q

Cryptography

A

The practice of encoding information in a manner that it cannot be decoded without access to the required decryption key.

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2
Q

What are the four common goals of Cryptography?

A

Two stem from the CIA Triad and the other two do not:

  1. Confidentiality
  2. Integrity
  3. Authorization
  4. Non-Repudiation
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3
Q

Cipher

A

A method used to scramble or obfuscate characters to their value.

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4
Q

Substitution Cipher

A

A type of coding or ciphering system that changes one character or symbol into another.

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5
Q

Stream Cipher

A

Operate on one character or bit of a message (or data stream) at a time.

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6
Q

Block cipher

A

Operate on “chunks,” or blocks, of a message and apply the encryption algorithm to an entire message block at the same time.

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7
Q

Transposition Cipher

A

Transposing or scrambling the letters in a certain manner.

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8
Q

Steganography

A

The art of using cryptographic techniques to embed secret messages within another file. Like hiding messages in images.

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9
Q

Symmetric Cryptosystems

A

Use a shared secret key available to all users of the cryptosystem.

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10
Q

Asymmetric Cryptosystems

*keys

A

Uses individual combinations of public and private keys for each user of the system.

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11
Q

What is the most common way to protect network communications using sensitive data?

A

With the (TLS) Transport Layer Security Protocol.

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12
Q

Full Disk Encryption (FDE)

A

A form of encryption where all data on a hard drive is automatically encrypted, including the operating system and system files.

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13
Q

Partition Encryption

A

Similar to FDE but targets a specific partition of a hard drive instead of the entire disk.

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14
Q

File-Level Encryption

A

This method allows users to encrypt specific files rather than entire drives or partitions. Not as secure as FDE or partition encryption.

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15
Q

Volume Encryption

A

Involves encrypting a set “volume” on a storage device, which could contain several folders and files.

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16
Q

Database Encryption

A

A method used to protect sensitive information stored in a database from access by unauthorized individuals. There are two types: TDE and CLE.

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17
Q

Transparent Data Encryption (TDE)

A

Encrypts entire databases.

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18
Q

Column-Level Encryption (CLE)

A

Allows specific columns within tables to be encrypted.

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19
Q

Record-Level Encryption

A

It allows individual records within a database to be encrypted.

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20
Q

Cryptographic Keys

A

Nothing more than a number, usually a very large binary number.

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21
Q

Key Space

A

The range of values that are valid for use as a key for a specific algorithm. The total set of possible keys that can be used in an encryption system. The larger the key space, the harder it is for an attacker to guess the correct key through brute force.

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22
Q

Key Length

A

The number of binary bits (0s and 1s) in the key.

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23
Q

Key Exchange

A

The secure distribution of the secret keys required to operate the algorithms. The three main methods are offline distribution, public key encryption, and the Diffie–Hellman key exchange algorithm

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24
Q

Kerckhoffs’ Principle

A

Also known as Kerckhoffs’ assumption, is that a cryptographic system should be secure even if everything about the system, except the key, is public knowledge. The principle is basically: The enemy knows the system.

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25
Cryptanalysis
The study of methods to defeat codes and ciphers.
26
Key Management Practices
The security measures taken by cryptosystem users and administrators to protect the security of the keying material.
27
If Alice wants to send a message to Bob using public key cryptography, what key should she use? How would she decrypt the ciphertext?
She would create the message and then encrypt it using Bob's public key. The only way to decrypt it is to use Bob's private key.
28
What is the offline distribution of keys?
One party provides the other party with a sheet of paper or piece of storage media containing the secret key.
29
The AES Cipher allows the use of three key strengths, what are the bit sizes?
128 bits (10 rounds of encryption) , 192 bits (12 rounds of encryption), 256 bits (14 rounds of encryption).
30
Diffie-Hellman Algorithm
A key exchange protocol that allows two parties to securely share a cryptographic key over an insecure channel. It uses a formula.
31
Split Knowledge
For sensitive keys, consider providing two different individuals with half of the key. They then must collaborate to re-create the entire key.
32
Key Escrow
Systems have a third party store a protected copy of the key for use in an emergency.
33
Key recovery
Organizations may have a formal key recovery policy that specifies the circumstances under which a key may be retrieved from escrow and used without a user’s knowledge.
34
RSA public key algorithm
A widely used asymmetric encryption technique for secure data transmission. RSA relies on the mathematical difficulty of prime factorization.
35
Elliptic Curve Cryptography (ECC)
Can be determined using this equation [ y^2 = x^3 + ax + b ]. Computer Scientists and Mathematicians believe it is extremely hard to find x. It is believed to be harder than RSA. It's a powerful encryption method that provides strong security with smaller key sizes compared to traditional RSA.
36
Message Digest
The unique output value derived from the content of a message through hashing.
37
Secure Hash Algorithm (SHA)
SHA (Secure Hash Algorithm) ensures **data integrity** by creating unique, fixed-length **message digests**. Variants like **SHA-1, SHA-256, and SHA-512** produce hashes from **160 to 512 bits**. It’s secure because: 1. **Nearly impossible** to reverse-engineer a message from its hash. 2. **Two different messages almost never** have the same hash. Even a tiny data change results in a completely different hash, making SHA essential in **cybersecurity, digital signatures, and authentication**.
38
Hash-Based Message Authentication Code (HMAC)
This algorithm implements a partial digital signature it guarantees the integrity of a message during transmission, but it does not provide for non-repudiation.
39
If you want to encrypt a message...
use the recipient's public key.
40
If you want to decrypt a message...
use your private key.
41
If you want to digitally sign a message you are sending to someone else...
use your private key.
42
If you want to verify the signature on a message sent by someone else...
use the sender's public key.
43
Public Key Infrastructure (PKI)
A hierarchy of trust relationships. These trusts permit combining asymmetric cryptography with symmetric cryptography along with hashing and digital certificates, giving hybrid cryptography It ensures that data remains confidential, authentic, and tamper-proof.
44
Certificate Authorities (CA)
CAs are the glue that binds the public key infrastructure together. These neutral organizations offer notarization services for digital certificates.
45
Registration Authorities (RA)
RAs assist CAs with the burden of verifying user's identities prior to issuing digital certificates.
46
Root Certificate
The top-level certificate for an entire PKI that serves as the root of trust for all certificates issued by the CA.
47
Offline CAs
Used to protect the root certificate. A highly secure CA that is disconnected from any network to prevent unauthorized access. It is typically used as a root CA in a Public Key Infrastructure (PKI) to issue certificates to intermediate CAs, which handle day-to-day certificate managemen
48
Certificate Chaining
The use of a series of intermediate CAs in the certificate authority trust model.
49
Intermediate CAs
Acts as a bridge between the Root CA and end-user certificates in a Public Key Infrastructure (PKI). It helps distribute trust while maintaining security
50
Certificate signing request (CSR)
Provides your public key to the certificate authority to create an X.509 digital certificate containing your identifying information and a copy of your public key. The CA then digitally signs the certificate using the CA’s private key and provides you with a copy of your signed digital certificate.
51
Extended validation (EV) certificates
Provide a higher level of assurance and the CA takes steps to verify that the certificate owner is a legitimate business before issuing the certificate.
52
Certificate revocation list (CRL)
Used to ensure that the certificate was not revoked.
53
Online Certificate Status Protocol (OCSP)
A real-time facility for verifying the validity of a digital certificate and confirming that it has not been revoked by the issuing certificate authority.
54
Certificate Stapling
A method that improves SSL/TLS certificate verification by allowing a web server to fetch and cache the CA’s signed response about the certificate’s status. This "stapled" response is sent with the TLS handshake, eliminating the need for browsers to query the CA directly. Benefits: -Faster connections by reducing extra verification steps -Enhanced privacy since users don’t contact the CA -Improved security through efficient validity checks
55
Hardware Security Models (HSMs)
A crypto processor used to manage/store digital encryption keys, accelerate cryptographic operations, support faster digital signatures, and improve authentication.
56
Frequency analysis
A cryptographic analysis or attack that looks for repetition of letters in an encrypted message and compares that with the statistics of letter usage for a specific language, such as the frequency of the letters E, T, A, O, N, R, I, S, and H in the English language.
57
Known Plain Text Attack
This attack relies on the attacker having pairs of known plain text along with the corresponding ciphertext.
58
Chosen Plain Text Attack
In this attack, the attacker obtains the ciphertexts corresponding to a set of a plain texts of their own choosing. This allows them to attempt to derive the key used and thus decrypt other messages encrypted with that key.
59
Related Key Attack
A hacker analyzes patterns between multiple secret keys to find weaknesses and decrypt data, exploiting connections between keys rather than guessing one. Used to break insecure systems like WEP. Prevented by avoiding predictable key patterns.
60
Birthday Attack
A cryptographic attack that exploits the probability theory to find hash collisions more efficiently than brute-force methods. Instead of checking every possible input, it takes advantage of the chance that two different inputs might accidentally create the same encoded output, making it easier to find a collision.
61
Downgrade Attack
It is used against secure communications such as TLS. The idea is to trick the user into shifting to a less secure version of the protocol, one that might be easier to break.
62
Salting
This adds a randomly generated value to each password prior to hashing.
63
Key Stretching
Used to create encryption keys from passwords in a strong manner. This uses thousands of iterations of salting and hashing to generate encryption keys that are resilient against attack.
64
Lightweight Cryptography
A form of encryption designed for resource-constrained devices such as small IoT devices, or medical implants. Traditional cryptographic algorithms can be too resource-intensive for these constrained environments, so lightweight cryptography provides security while minimizing processing, memory, and energy consumption.
65
Homomorphic Encryption
A cryptographic method that allows computations on encrypted data without decrypting it, ensuring privacy while still enabling analysis.

CompTIA Security+ Study Guide by Mike Chapple (16 decks)

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