Domain 3: Security Architecture and Engineering Flashcards
Algorithm
A mathematical function used in the encryption and decryption processes. It may be quite simple or extremely complex. Also defined as the set of instructions by which encryption and decryption is done.
Asymmetric Encryption
Process that uses different keys for encryption than it does for decryption, and in which the decryption key is computationally infeasible to determine given the encryption key itself, from plaintext and corresponding ciphertext, or from knowledge of the key generation or encryption algorithm.
Block Mode Encryption
Using fixed-length sequences of input plaintext symbols as the unit of encryption.
Ciphertext
The altered form of a plaintext message so as to be unreadable for anyone except the intended recipients. In other words, it has been turned into a secret.
Collision
This occurs when a hash function generates the same output for different inputs. In other words, two different messages produce the same message digest.
Crime Prevention Through Environmental Design (CPTED
An architectural approach to the design of buildings and spaces, which emphasizes passive features to reduce the likelihood of criminal activity
Cryptanalysis
The study of techniques for attempting to defeat cryptographic techniques and, more generally, information security services.
Cryptographic Hash, Cryptographic Hash Function
A process or function that transforms an input plaintext into a unique value called a hash (or hash value). These do not use cryptographic algorithms; the term “cryptographic” refers to the assertion that strong hash algorithms are one-way functions; that is, it is computationally infeasible to determine the input plaintext from the hash value and knowledge of the algorithm alone. Message digests are an example of the use of a cryptographic hash.
Cryptography
The study or applications of methods to secure or protect the meaning and content of messages, files, or other information, usually by disguise, obscuration, or other transformations of that content and meaning.
Cryptosystem
The complete set of hardware, software, communications elements, and procedures that allows parties to communicate, store information, or use information that is protected by cryptographic means. The system includes the algorithm, key, and key management functions, together with other services that can be provided through cryptography.
Cryptovariable
One or more parameters inherent to a particular cryptographic algorithm and its implementation in a cryptosystem. Block size, key length, and number of iterations (or rounds) are examples.
Decoding
The reverse process of encoding, converting the encoded message back into its plaintext format.
Decryption
The reverse process of encryption. It is the process of converting a ciphertext message back into plaintext using the cryptographic algorithm and appropriate key for decryption (which is the same for symmetric encryption, but different for asymmetric encryption). This term is also used interchangeably with “deciphering.”
Encoding
The action of changing a message or other set of information into another format using a code. Unlike encryption, which obscures or hides the meaning, encoded information can still be read by anyone with knowledge of the encoding process.
Encryption
The process and act of converting the message from its plaintext into ciphertext. Sometimes it is also referred to as enciphering. The two terms are sometimes used interchangeably in literature and have similar meanings.
Encryption System
The total set of algorithms, processes, hardware, software, and procedures that taken together provide an encryption and decryption capability.
Frequency Analysis
A form of cryptanalysis that uses the frequency of occurrence of letters, words, or symbols in the plaintext alphabet as a way of reducing the search space.
Hybrid Encryption System
A system that uses both symmetric and asymmetric encryption processes.
In Band
Refers to transmitting or sharing control information, such as encryption keys and cryptovariables, over the same communications path, channel, or system controlled or protected by that information.
Key
The input that controls the operation of the cryptographic algorithm. It determines the behavior of the algorithm and permits the reliable encryption and decryption of the message.
Key Escrow
A process by which keys (asymmetric or symmetric) are placed in a trusted storage agent’s custody for later retrieval. The trustworthiness of the encryption system(s) being used is thus completely placed in the escrow agent’s control.
Symmetric cryptosystem
use a shared secret key available to all users of the cryptosystem
Integrity
ensures that data is not altered without authorization
Digital signatures
Message integrity is enforced through the use of encrypted message digests
a recipient can verify the message digest is valid and data not altered in transit
Key space
the range of values that are valid for use as a key for a specific algorithm
Kerckhoff’s Principle
that a cryptographic system should be secure even if everything about the system, except the key, is public knowledge
Cryptovariables
cryptographic keys
One way function
hash, mathematical operation that easily produces output values for each possible combination of inputs but makes it impossible to retrieve the input values
Nonce
is a random number that acts as a placeholder variable in mathematical functions
Split knowledge
separation of duties and two-person control contained in a single solution
Recovery agent
the third party in a split knowledge setup, that uses the key escrow
Transposition Ciphers
uses an encryption algorithm to rearrange the letters of a plaintext message
Columnar transposition
Substitution cipher
use the encryption algorithm to replace each character or bit of the plaintext message with a different character
Caesar Cipher, ROT13, Vigenere system
One Time Pad
use a different substitution alphabet for each letter of the plaintext message.
- must be randomly generated
- must be physically protected against disclosure
- each one-time pad must only be used once
- the key must be as long as the message to be encrypted
Block cipher
operate on chunks or blocks, of a message and apply the encryption algorithm to an entire message block at the same time
most modern encryption algorithms use a type of block cipher
Stream cipher
operate on one character or bit of the message at a time
one-time pad, caesar cipher
Hybrid cryptography
Combines both Symmetric and Asymmetric key encryptions because of the slow speed of operation for asymmetric.
Hashing collision
Occurs when a hash function creates the same value for two different methods. Two messages create the same hash value
Electronic Code Bock (ECB)
Least secure, encrypts blocks of 64 meaning encrypted blocks could repeat. More easy to break because of the less randomness
Cipher block Chaining Mode (CBC)
each block of unencrypted test is XORed with the block of ciphertext immediately preceding it before it is encrypted
encryption blocks are chained together
Cipher Feedback (CFB)
Streaming cipher version of CBC. Uses memory buffers in real time instead of blocks. bit by bit
Output feedback mode (OFB)
Ciphers operate in almost the same fashion as they do in CFB, but instead of being XORed it XORs the plaintext with a seed value, no chaining functions and transmission errors do not propogate
Counter Mode (CTR)
uses a stream cipher similar to that used in CFB and OFB Just uses a counter instead of a seed value
Galois/Counter Mode (GCM)
same as CTR but includes authentication tags to the encryption process for more authenticity
Data Encryption Standard (DES)
56-bit and operates in long series of XOR operations, lots of flaws, not secure anymore. Operates in all the cipher modes
Triple DES
slightly stronger than DES, but 3 keys and longer 168-bit, flawed and should not be used
Blowfish
Block cipher, 64-bit, key length 32-448 bits
Skipjack
Block Cipher, 64-bit, 80-bit key
Rivest cipher 4 (RC4)
Stream Cipher, 40-2048bits, key, no block size
Rivest Cipher 5 (RC5)
block: 32, 64, 128 Key 0-2040
Rivest Cipher 6 (RC6)
Block: 128, Key: 128, 192, 256
Skipjack
Block Size: 64 Key 80
3DES
Block size: 64 Key: 112 or 168
CAST-128
Block: 64 Key: 40-128
CAST-256
Block 128 Key: 128, 160,192, 224, 256
Offline distribution
Physical exchanging of keys
Public Key Encryption
Use of a public key to setup initial communication, once the link is established a secret key can be securely transferred over the public key link.
Hardware Security Module (HSM)
Dedicated hardware devices used to manage crypto keys. Expensive to implement
Symmetric Key Exposure Formula
of keys = n(n-1) / 2
Hashed Message Algorithm Code (HMAC)
implements a partial digital signature, guarantees the integrity of a message during transmissions
does not provide nonrepudiation
Digital Certificates
provide communication parties with the assurance that the people they are communicating with truly are who they claim to be.
Digital Certificate Standard
X.509 - which means they conform to the long list of data contained certificate.
serial number, issuer name, signature algorithm, validity period, public key, and more
Certificate Authority
the glue that binds the public key infrastructure together, being a neutral organization that notarizes digital certificates.
Registration Authorities
assist Certificate authorities by taking the burden of verifying user’s identities prior to issuing a digital certificate.
Self-signed certificates
for use inside an organization, may be configured to trust the internal CA, saving some expense for obtaining it from a third party.
Certificate Signing Request
after properly enrolling with a CA by identifying yourself, this request takes your public key and the CA creates an X.509 digital certificate registered to you
S/MIME
x.509 certificate for exchanging keys. Uses RSA encryption algorithm standard for encrypted email
Transport Layer Security (TLS)
Uses the exchange of digital certificates to negotiate encryption/decryption between the browser and web server.
Creates that secure communication between a user browsing a website
Perfect forward secrecy
layers of encryption prevent nodes in the relay chain from reading anything other than the specific information they need to accept and forward the traffic
Steganography
art of using cryptographic techniques to embed secret messages within another message
Link Encryption
protects communication circuits by creating a secure tunnel between two points. Everything including the header, trailer, address, and routing data is encrypted
End-to-End Encryption
protects communication between two parties and is performed independently of link encryption
Faster that link because it does not encrypt headers, addresses, routing data and therefor susceptible to eavesdropping