Domain 3 Flashcards
_____, are always meant to hide the true meaning of a message.
Cyphers
Cryptographic systems of symbols that operate on words or phrases and are sometimes secret but don’t always provide confidentiality
Code
is a symmetric key cipher where plaintext digits are combined wit pseudorandom cipher digit stream(keystream). In a _____ _____, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, to give a digit of the cipher text stream.
Stream Cypher
is a method of encrypting text (to produce ciphe rtext) in which a cryptographic key and algorithm are applied to a block of data(for example, 64 contiguous bits) at once as a group rather than to one bit at a time
Block Cypher
is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the “units” may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth.
Substitution
uses an encryption algorithm to rearrange the letters of a plaintext message, forming the ciphertext message.
Transposition
is a random bit string (a nonce) that is the same length as the block size that is XORed with the message. ___ are used to create a unique cipher text every time the same message is encrypted with the same key.
Initialization Vector (IV)
This stream cypher uses a key of length one
Ceasar
This stream cypher uses a longer key (Usually a word or sentence)
Vigenere
This stream cypher uses a key that is as long as the message itself
One-time pad
One Time Pad Success Factors (4)
The key must be generated randomly without any known pattern.
At least as long as the message to be encrypted.
The pads must be protected against physical disclosure
Each pad must be used only one time and then discarded
____________ is a communication concept. A specific type of information is exchanged, but no real data is transferred, as with digital signatures and digital certificates.
Zero-knowledge proof
A concept that enabled one to prove knowledge of a fact to another individual without revealing the fact it itself.
Zero-knowledge proof
Which concept ensures that no single person has sufficient privileges to compromise the security of the environment
Split knowledge
_____ ______ means that the information or privilege required to perform an operation is divided among multiple users.
Split knowledge
is a way to measure the strength of a cryptography system by measuring the effort in terms of cost and/ or time to decrypt messages.
Also know as the time and effort required to break a protective measure
Work function or work factor
Modern cryptosystems utilize keys that are at least ____ bits long to provide adequate security
128
Relies on the use of a shared secret key. Lacks support for scalability, easy key distribution, and nonrepudiation
Symmetric Encryption
Public-private key pairs for communication between parties. Supports scalability, easy key distribution, and nonrepudiation
Asymmetric Encryption
Which DES or 3DES mode is the Simplest & least secure mode. Processes 64-bit blocks, encrypts block with the chosen key. If same block encountered multiple times, same encrypted block is produced, making it easy to break
Electronic Codebook Mode (ECB)
Using this DES or 3DES mode, Each block of unencrypted text is XORed with the block of ciphertext immediately preceding. Decryption process simply decrypts ciphertext and reverses the XOR operation.
Cipher Block Chaining (CBC)
This DES or 3DES mode is the streaming version of CBC. Works on data in real time, using memory buffers of same block size. When buffer is full, data is encrypted and transmitted. Uses chaining, so errors propagate.
Cipher Feedback (CFB)
This DES or 3DES mode operates similar to CFB, but XORs the plain text with a seed value. No chaining function, so errors do not propagate.
Output Feeback (OFB)
This DES or 3DES mode uses an incrementing counter instead of a seed. Errors do not propagate.
Counter (CTR)
