Questions tagged [primitive-roots]

For questions about primitive roots in modular arithmetic, index calculus, and applications in cryptography. For questions about primitive roots of unity, use the (roots-of-unity) tag instead.

394 questions
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Finding all solutions of 'Discrete Root'

Ques: $x^k \equiv a \pmod n$, where n is prime. What are the possible values of x? I know how to find a discrete root using both primitive root and discrete logarithm concepts. But I am wondering ...
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Let $w \in G_{15}$ be a primitive root. Find every $n \in \mathbb{N}$ such that $\sum_{i=2}^{n-1} w^{3i} = 0$

We can first rewrite the series in a useful form, $$\sum_{i=2}^{n-1} w^{3i} = \bigg( \sum_{i=0}^{n-1} w^{3i} \bigg) - w^3 - 1$$ But since $w$ is primitive, we can apply the geometric series formula,...
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Isn't primitive root co-prime with corresponding modulo value?

Suppose, g is a primitive root modulo n. Therefore, $g^{\phi(n)} \equiv 1 \pmod n$ then g is always co-prime to n? Isn't it?
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Prove reciprocal polynomial is not primitive(field).

Let $f$ be a polynomial with a non-zero constant term and define its reciprocal polynomial $f^*=x^nf(\frac{1}{x})$. (Here $\deg {f}=n$. I see several other names like "reverse/inverse polynomial", and ...
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proving that an element g is primitive

How do I go about proving that an element g is primitive? If I let p be a prime. Is it then the same as proving that every non-zero element in $Z_p$ can be written as a power of g?
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Sign of these complex embeddings

Let $\alpha$ be a root of $f = x^4 - 7$, hence $\alpha$ is a fourth root of $7$. Consider the number field $F = \mathbb{Q}(\sqrt[4]{7})$, which is of degree $4$. Since it is of degree $4$, there ...
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upper bound on, or fast algorithm to find, an order $2^n$ element in the multiplicative group modulo prime $q(2^n)+1$

I have a program which (in its current implementation) requires, for a given $N=2^n$, some $\omega$ in some field such that $\omega^N=1$ and $\omega^i\ne1$ for each $0<i<N$. Complex roots of ...
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How does Fermat's Little Theorem help find primitive roots of unity?

I am asked to find the primitive roots of unity mod 23, and recommended to use Fermat's Little Theorem to help simplify calculation. I know that, once I've found one, I can find all others by finding ...
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Prove that there are infinitely many primes which are primitive roots modulo $N$

Assuming $N$ has a primitive root, show that there are infinitely many primes which are primitive roots modulo $N$. It is obviously true using Dirichlet's theorem on primes, but I want to prove ...
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If $p$ is an odd prime and $k$ an integer with $0<k<p-1$ then $1^k + 2^k + \ldots + (p-1)^k$ is divisible by $p$

If $p$ is an odd prime and $k$ an integer with $0<k<p-1$ prove that $1^k + 2^k + \ldots + (p-1)^k$ is divisible by $p$. Given hint: use primitive root. This is a question on a practice final of ...
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Given 2 is a primitive root mod 19, find all solutions to x^12 ≡ 7 (mod 19) (a) x^12 ≡ 6 (mod 19)

I'm stuck on (another) problem under Number Theory. There are quite a few gaps on what was covered in my class so I'm having quite a bit of trouble. Could you please help me solve the following ...
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Any finite field of $q$ elements has exactly $\Phi(q-1)$ primitive roots

Is the following prove of the above statement correct? $\bullet\$Any finite field of $q$ elements is isomorphic to $\mathbb{F}_q$ and we know that $\mathbb{F}_q^*$ is a cyclic group of $q-1$ ...
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Use primitive root to prove if $a^{\phi(m)/2}\equiv 1\pmod m$ then $a$ is a quadratic residue modulo $m$.

This is trivial in arguments of quadratic residues, but I couldn't solve it using primitive root. The problem seeks to use primitive root to be proved. Problem: Let $m>2$ be an integer having a ...
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If $(a,m)=(b,m)=1$ and if $(\exp_m(a),\exp_m(b))=1$, prove that $\exp_m(ab)=\exp_m(a)\exp_m(b).$

If $(a,m)=(b,m)=1$ and if $(\exp_m(a),\exp_m(b))=1$, prove that $$\exp_m(ab)=\exp_m(a)\exp_m(b).$$ The notation $\exp_m(a)$ is denote the smallest positive integer $n$ such that $a^n\equiv 1\pmod m$. ...
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Certain conditions for primitive roots of $n$.

Let $a$ be a primitive root for modulo $n$. Then, $a^{\frac{\phi(n)}{2}}\equiv-1\pmod{n}$. I have a question for its converse. In general, its converse is false. Is it possible to make(it means '...
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Number of solutions of $x^e \equiv c \mod p$

We have to find the number of solutions to the equation:- $$x^e \equiv c \mod p$$ where $c \not\equiv 0\mod p$. For $c=1$, we can prove that the above has $\gcd(e,p-1)=d$ solutions in the following ...
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A question about a primitive root mod $p=2^{2^k}+1$, where $p$ is prime.

Let $p=2^{2^k}+1$ be a prime where $k\ge1$. Prove that the set of quadratic non-residues mod $p$ is the same as the set of primitive roots mod $p$. Use this to show that $7$ is a primitive root mod $p$...
The set of the primitive roots modulo $p$, with $p$ a fermat prime
"Let $p$ be a prime of the form $2^{2^{n}}+1$, with $n \in \mathbb{N}$ (This means $p$ is a Fermat prime) Using Euler's Criterion, prove that the set of primitive roots mod $p$ is equal to the set ...