Chapter 3 - preliminary concepts Flashcards
What are the three identities of a byte?
- It’s a string of 8 logical or false values
- It’s an 8 bit binary number
- It’s a representation of some character(e.g., letter, digit, punctuation, part of a logogram)
What is a function?
- Takes one or more values and returns another values as a result
What are the values passed into a function called?
- Arguments
What is the value returned by a function called?
- result
If a function is denoted by a symbol what is it called?
- An operator
If there is one argument for an operator where is the operator placed?
- In front of the argument
If there are two arguments for an operator where is the operator placed?
- In between the arguments
If a function contains letters as arguments how are the arguments represented?
- arguments are contained in parenthesis and each is separated by a coma
What are boolean operators?
- Functions that operate on bits that represent truth values
What are the properties of the logical ‘not’ operator?
- Functions that operate on bits that represent truth values
What are the properties of the logical ‘and’ operator?
- Functions that operate on bits that represent truth values
What are the properties of the logical ‘or’ operator?
- Functions that operate on bits that represent truth values
What are the properties of the logical ‘or’ operator?
- A xor B, is true if exactly one of A or B is true, otherwise it is false
How is the logical ‘and’ operator represented?
- with the character ‘/\’
How is the logical ‘or’ operator represented?
- with the character ‘\/’
Which operator is used extensively in cryptography?
- XOR
What is an exponential?
- a number that is multiplied by itself a specified number of times
How is an exponential expression BE read?
- B to the E power
Given an exponential expression BE .What is B and E?
- ‘B’ is the base and ‘E’ is the exponent
If N is any number then what is N1
- it’s the number ‘N’
By convention what is N0 given N is non zero
- 1
By convention what is 00
- 0
What is meant by writing a decimal number 3456
- 3×1000+4×100+5×10+6×1
What is exponential representation of a decimal number 3456
- 3×103 + 4×102+5×101+6×100
What is a way exponents are used in cryptography?
- exponents are used to convert letters to numbers
How can large numbers be represented?
- they can be represented in exponential notation
What is another term used for exponential notation?
- scientific notation
How is 12,300,000 represented in scientific notation?
- 1.23 x 107
How are integers > 1 classified?
- They’re either prime or composite numbers
When is a number called a composite?
- When the number is a product of two smaller numbers
When is a number called a prime?
- When the number is not product of two smaller numbers
What number is neither prime or composite?
- 1
What is an important property of the number 1?
- It’s neither a prime or a composite number
What is an important property of prime numbers?
- any number can be written as the product of prime numbers in only one way (aside from the order of the factors)
What are the prime factors of a number?
- the set of prime numbers that can evenly divide the number
What is an important characteristic of a set of prime factors of an integer?
- the set of prime factors is unique for the integer
What is the process of determining the prime factors of an integer?
- Factoring or Factorization
What is the term for two numbers that have no prime factors in common?
- They are called coprime
What does it mean if two numbers are coprime ?
- They don’t have any common prime factors
What is another way of saying a number is coprime?
- The number is mutually prime
If N is an integer then what two numbers are always coprime?
- N and 1
When are N and 0 coprime?
- When N is 1
When two numbers are always coprime?
- N and N+1
What is the result when two integers are divided?
- A quotient and a remainder
Given positive integers A and B. What is the result when dividing A by B?
- A quotient and a remainder
Given positive integers A and B. If A is divided by B? What is the term for B
- B is the divisor
What is a divisor?
- Given positive integers A and B. If A is divided by B then B is the divisor
Given positive integers A and B. If A is divided by B. What is a remainder?
- The remainder is A-QB
Given positive integers A and B. If A is divided by B. What is a quotient?
- The quotient Q is the largest number such that Q * B doesn’t exceed A
What is modulo arithmetic?
- The study of remainders
What is ignored in modulo arithmetic?
- The quotient
What is the divisor called in modulo arithmetic?
- The modulus
What is the remainder called in modulo arithmetic?
- The residue
Given a modulus is N and two numbers X and Y have the same residue what is the term for X and Y
- X and Y are said to be congruent modulo N
if X and Y are said to be congruent modulo N what is true
- X and Y both have a modulus of N and they have the same residue
if X and Y are said to be congruent modulo N what is true
- X and Y both have a modulus of N and they have the same residue
How is it written given X and Y are congruent modulo N
- X ≡ Y Mod(N)
What does the expression ‘X mod Y’ do?
- It gives the remainder of dividing X by Y
What is the additive inverse of a number A?
- It’s the opposite of the number A
If you add a number with it’s additive inverse what do you get?
- 0
What is the multiplicative inverse of a number?
- It’s the inverse of the number
What do you get if you multiply a non-zero number by it’s multiplicative inverse?
- 1
