Cryptography Flashcards
Plaintext or Cleartext
Original message, readable by attacker
Ciphertext or Cryptogram
Altered message that is unreadable to anyone except the intended recipients, unreadable by attacker
Encryption
Process of converting plaintext to ciphertext
Decryption
Going from ciphertext to plaintext using the cryptographic algorithm and the key
Algorithm
Mathematical function used in the encryption and decryption process
Key or Cryptovariable
Sequence that controls the operation of the cryptographic algorithm, determines behavior of algorithm and permits reliable encryption and decryption of message
Nonrepudiation
Security service by which evidence is maintained so that the sender and the receiver of data cannot deny having participated in the communication
Cryptosystem
Entire cryptographic operation (including algorithm, key, and key management functions)
Cryptanalysis
Study of techniques for defeating cryptographic techniques and by extension security services
Cryptology
Science that deals with hidden, disguised or encrypted communications
Includes communications security and communications intelligence
Collision
Occurs when a hash function generates the same output for different inputs
Key Space
Total number of possible values of keys in a cryptographic algorithm or other security mechanism
2^n (n=length of key in bits)
Work Factor
Time and effort required to break a protective measure
Initialization Vector (IV)
Non-secret binary vector (block of bits) used as the initializing input for the encryption of a plaintext sequence
Increases security by introducing additional cryptographic variance to create unique ciphertext using the same key
Must be known to the recipient to decrypt message
Encoding and Decoding
Encoding: action of changing a message to another format through the use of a code (i.e. message to Morse)
Decoding: converting encoded message into plaintext
*Has nothing to do with encryption
Transposition or Permutation
Reordering plaintext to hide the message
Substitution
Process of exchanging one letter (or byte) for another
SP-Network
Substitution and Permutation
Adds confusion and diffusion to the process
Confusion
Provided by mixing/changing key values used during the repeated rounds of encryption
Diffusion
Mixing up the location of the plaintext throughout the ciphertext
Location of first character of plaintext may change several times during the encryption process due to transposition
Avalanche Effect
Designing algorithms where a minor change in either the key or the plaintext will have a significant change in the resulting ciphertext
Confusion and diffusion
Strong hashing algorithm
Link Encryption
Encrypts all data along communications path (including router information which provides traffic confidentiality)
End-to-End Encryption
Data is encrypted in the beginning and is not decrypted until it reaches the end
Usually performed by end-user
Routing information remains visible
