Flashcards
SRSC - Teste I 2
Cards in this deck (7)
- 1Dê exemplos de Algoritmos de Cifras de BlocosAES; 3DES; Blowfish; RC5; RC6; Tootfish; Camelia
- 2Dê exemplos de Algoritmos de Streams CiphersRC4; A5/1; A5/2
- 3Dê exemplos de Block Ciphers que possam ser usados com chaves de múltiplos tamanhosAES; Camelia; RC5
- 4Como funciona o algoritmo 3DES?3DES uses three keys and three executions of the DES algorithm.The function
follows an encrypt-decrypt-encrypt (EDE) sequence, its only advantage is that it allows users of 3DES to
decrypt data encrypted by users of the older single DES.
With three distinct keys, 3DES has an effective key length of 168 bits. FIPS 46-3
also allows for the use of two keys, with K1=K3; this provides for a key length of 112 bits. - 5Descreve o mecanismo de segurança HMACThe advantage of using a hash-based MAC as opposed to a MAC based a block cipher is speed. Hash functions like MD5 and SHA are generally faster in software than symmetric block ciphers like AES and DES.
A hash function cannot be used directly as a MAC since it does not rely on a secret key. The design objectives for an HMAC are the following:
-The ability to use available hash functions without modification.
-The ability to easily replace the embedded hash function in case faster or more secure functions become available.
-The ability to preserve the original performance of the hash function.
-The ability to use keys in a simple way.
A well understood cryptographic analysis of the strength of the authentication mechanism. - 6Descreve o mecanismo de segurança CMACThe Cipher-based
Message Authentication Code (CMAC) mode of operation is for use with AES and
triple DES
The only reason CMAC, which requires double the number of calls to the block cipher for encryption, would be used is if it is being used on an embedded system which already has hardware acceleration for the cipher, making it easy to re-purpose it for authentication - 7Quais os diferentes tipos de Ataques de Cripta-Análise?CIPHERTEXT-ONLY:
-Easiest to Defend
-Encryption Algorithm
-CipherText to decode
KNOWN-PLAINTEXT:
• Encryption algorithm
• Ciphertext to be decoded
• One or more plaintext–ciphertext pairs formed with the secret key
CHOSEN-PLAINTEXT:
Encryption algorithm
• Ciphertext to be decoded
• Plaintext message chosen by cryptanalyst, together with its corresponding ciphertext
generated with the secret key
CHOSEN-CIPHERTEXT:
• Encryption algorithm
• Ciphertext to be decoded
• Purported ciphertext chosen by cryptanalyst, together with its corresponding
decrypted plaintext generated with the secret key
Information
- Description
- Flashcards on SRSC - Teste I 2, created by Bruno Ramos on 27/07/2019.
- Created by
- Bruno Ramos
- Views
- 0
- Rating