Flashcards
SCC 363 - Crypto 3
Cards in this deck (13)
- 1State the four different threat models for symmetric encryption?Cipher text only attack
Known plain text attack
Chosen plain text attack
Chosen cipher text attack - 2State the three goals attempted to achieve via the use of keys as a form of encryption?Impossible for attacker to learn the key
Impossible for attacker to learn the plain text from cipher text
Impossible for the attacker to learn any character of the plain text from the cipher text - 3Finish the sentence: A good secured encryption mechanisms ensures that regardless of an attacker gaining prior information about the plain text, the cipher text ........A good secured encryption mechanisms ensures that regardless of an attacker gaining prior information about the plain text, the cipher text should leak no additional information about the plain text.
- 4Describe Shannon's idea about achieving perfect secrecy??
- 5What is perfect secrecy?Perfect secrecy means that observing the ciphertext should not change the attacker’s knowledge about the distribution/content of the plaintext
- 6What is the one time pad?The One Time Pad (OTP) is information-theoretic secure, which means it can't be broken with cryptanalysis and there is not enough information. No amount of computation power and resources will solve this.
- 7State drawbacks of OTP?Key must be long as the message
- 8What is a stream cipher?A stream cipher is a symmetric key cipher where plain text digits are combined with a pseudo random cipher digit stream (keystream). In a stream cipher, each plain text digit is encrypted one at a time with the corresponding digit of the key stream, to give a digit of the cipher text stream.
- 9Why are stream ciphers bad for message integrity?An encrypted message needs additional integrity protection. Otherwise, it can be easily modified by a man-in-the-middle. If an attacker knows a certain portion of the message, they can change it to any other value without knowing the key.
- 10State the three different encryption modes?Cipher block chaining
Counter
Electronic code book - 11Describe the electronic book (ECB) encryption?Electronic Code Book (ECB) is a mode of operation for a block cipher, with the characteristic that each possible block of plaintext has a defined corresponding ciphertext value and vice versa. ...
- 12Describe the CBC encryption?Cipher block chaining (CBC) is a mode of operation for a block cipher (one in which a sequence of bits are encrypted as a single unit or block with a cipher key applied to the entire block). Cipher block chaining uses what is known as an initialization vector (IV) of a certain length.
- 13What is diffie-Hellman?Diffie-Hellman is an algorithm used to establish a shared secret between two parties. It is primarily used as a method of exchanging cryptography keys for use in symmetric encryption algorithms like AES.
It was one of the first public key protocol
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- dsdssd SCC 363 - Security and RIsk Flashcards on SCC 363 - Crypto 3, created by Ayo Olutobi on 24/11/2017.
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