Questão 5/10 - Matemática Computacional A criptografia tem quatro objetivos principais, que fornecem elementos essenciais à segurança da informação. Com base nisso, associe cada um desses objetivos, que se encontram na coluna à esquerda, com seu significado (coluna à direita). A ordem correta é:
A 1 – 3 – 4 – 2 B 3 – 1 – 4 – 2 C 1 – 4 – 2 – 3 D 3 – 2 – 4 – 1 E 3 – 1 – 2 – 4
No processo 2 a cifragem consiste em uma tabela De-Para, na qual a chave numérica representa as posições dos símbolos e a sequência na qual serão transpostas. Estão corretos apenas os itens: I II III IV A I e II B I e IV C II e III D II e IV E III e IV A B C D E
Consider the following text: 'ASUTOQ EAANA EMAHAR'. It was encrypted using two different processes. In process 1, each letter was replaced by another letter according to a fixed rule. In process 2, the letters were not changed, but were rearranged in a different order. Which of the following statements are correct? I. Both processes work at the bit level of the original message, therefore they require a computer to operate. II. Process 1 is a substitution cipher and process 2 is a transposition cipher. III. In process 1, the encryption is of the polyalphabetic type, that is, the letter exchange is variable, configuring a one-to-many relationship. IV. In process 2, the encryption consists of a De-Para table, in which the numeric key represents the positions of the symbols and the sequence in which they will be transposed. Choose the correct alternative:
I. Both processes work at the bit level of the original message, therefore they require a computer to operate. II. Process 1 is a substitution cipher and process 2 is a transposition cipher. III. In process 1, the encryption is of the polyalphabetic type, that is, the letter exchange is variable, configuring a one-to-many relationship. IV. In process 2, the encryption consists of a De-Para table, in which the numeric key represents the positions of the symbols and the sequence in which they will be transposed. A I and II B I and IV C II and III D II and IV E III and IV
The Euclidean algorithm is an efficient and simple way to find the GCD (greatest common divisor) for two integers different from zero. It has vast application in various areas and is used in many important applications, such as the RSA public key cryptography method. Regarding this algorithm, choose the correct alternative:
A. The Euclidean algorithm is an efficient and simple way to find the GCD for two integers different from zero through factorization. B. The central point of the Euclidean algorithm is the realization that a GCD can be calculated recursively. The remainder of the division in the first entry is used in the next step, until the quotient of some division results in 1. C. Let x and y be the values for which we want to calculate their GCD and r the remainder of the division of x by y, then the formulation of the Euclidean algorithm is: gcd(x,y) = gcd(r,x). D. Let x and y be the values for which we want to calculate their GCD and if gcd(x,y)=1 we say that x and y are multiples of each other. E. One of the realizations that contributed to the Euclidean algorithm is that if an integer d divides x, and d divides y, then d also divides the sum of x and y and also the subtraction between them.
Cryptography is the technique of transforming information in order to make its meaning unintelligible. Analyze the following statements regarding cryptography and its terminologies. I. It is not possible to encrypt media files, such as photos or videos, only written texts. II. Encrypted text is the name given to a text written in natural language (for example, Portuguese), which will undergo a process of encryption. III. One of the functions of a cryptographic algorithm is to decipher a text that has been encrypted, that is, to decrypt a text, so that it can be read again in natural language. IV. Encryption is the modification of the minimum elements of computation (i.e., bits) of what is being worked on (letters, numbers, etc.). Coding, on the other hand, is the modification of a set of information (words, phrases, etc.). Choose the correct alternative:
I. It is not possible to encrypt media files, such as photos or videos, only written texts. II. Encrypted text is the name given to a text written in natural language (for example, Portuguese), which will undergo a process of encryption. III. One of the functions of a cryptographic algorithm is to decipher a text that has been encrypted, that is, to decrypt a text, so that it can be read again in natural language. IV. Encryption is the modification of the minimum elements of computation (i.e., bits) of what is being worked on (letters, numbers, etc.). Coding, on the other hand, is the modification of a set of information (words, phrases, etc.). A I and III B I and IV C II and III D II and IV E III and IV