# How do you use Euclidean algorithm to find inverse modulo?

## How do you use Euclidean algorithm to find inverse modulo?

The greatest common divisor of integers a and b, denoted by gcd(a,b), is the largest integer that divides (without remainder) both a and b….Find the inverse of 15 mod 26.

Step 0: 26 = 1(15) + 11 p0 = 0
Step 4: 3 = 3(1) + 0 p4 = 25 – 2( 2) mod 26 = 21
p5 = 2 – 21( 1) mod 26 = -19 mod 26 = 7

## How do you solve an extended Euclidean algorithm?

The extended Euclidean algorithm

1. Set the value of the variable c to the larger of the two values a and b , and set d to the smaller of a and b .
2. Find the quotient and the remainder when c is divided by d .
3. If r = 0, then gcd( a , b ) = d .

What is extended Euclidean algorithm for multiplicative inverse?

Use the extended Euclidean algorithm to compute k−1, the modular multiplicative inverse of k mod 2w, where w is the number of bits in a word. This inverse will exist since the numbers are odd and the modulus has no odd factors.

### What is extended Euclidean algorithm in cryptography?

Extended Euclidean Algorithm is an extension of the Euclidean Algorithm that computes the greatest common divisor (GCD) of integers a and b. GCD is the largest integer that divides both a and b without any remainder.

### How do you solve inverse modulo?

A naive method of finding a modular inverse for A (mod C) is:

1. Calculate A * B mod C for B values 0 through C-1.
2. The modular inverse of A mod C is the B value that makes A * B mod C = 1. Note that the term B mod C can only have an integer value 0 through C-1, so testing larger values for B is redundant.

What is the difference between the Euclidean algorithm and the extended Euclidean algorithm?

The major difference between the two algorithms is that the Euclidean Algorithm is primarily used for manual calculations whereas the Extended Euclidean Algorithm is basically used in computer programs.

## What is the inverse of modulo?

For every number x from this set, calculate a * x mod m , i.e., the remainder from the division of a * x by m . The modular multiplicative inverse of a modulo m is the value of x for which this remainder is equal to 1 .

What is difference between Euclidean and extended Euclidean algorithm?

### What is the formula for Euclidean algorithm?

If we examine the Euclidean Algorithm we can see that it makes use of the following properties: GCD(A,0) = A. GCD(0,B) = B. If A = B⋅Q + R and B≠0 then GCD(A,B) = GCD(B,R) where Q is an integer, R is an integer between 0 and B-1.

### What is the inverse of 7 modulo 26?

15 modulo
So, the inverse of 15 modulo 26 is 7 (and the inverse of 7 modulo 26 is 15).