Can Prime numbers be negative? I was wondering, can a prime number be negative? We had a question over at security.se which stated that prime generation with openssl:
openssl dhparam -text 1024

results in a 1024-bit number to which leading zeros are added (resulting in 1032 bits). It could be the case that this is done to sign the integer,  however it was my believe that negative primes did not exist? 
 A: A prime number like $7$ represents all of the values that both divide 7 and are multiples of it.  Then 7 simply os the representive form of it.  So, of the integers, 7 represents both 7 and -7.
Sometimes you might want all primes to be 1 modulo 4 or 6, in which case, you might get -7 as the name form.
In other systems, like the gaussian integers, a prime likr $2+i$, can represent that and its multiples by powers of $i$.  Other systems, like $x+y\sqrt{2}$, a prime like $1+2\sqrt{2}$, is one of an infinite number of values that divide this, and are divisable by this prime.
For the integers, it is usually representive to make the name prime greater than zero.
A: Please refer to the below link:
Link
I think this explains the best.
A: Primes are always modulo units in algebra. For example, let $p(x)$ with coefficients in $\mathbb{R}$ be a polynomial that can not be divided by any other polynomial over $\mathbb{R}$. Then $a\cdot p(x)$ is prime for all $a\in \mathbb{R}$, $a\ne 0$.
A unit is an element with inverse, in this case $a$ is a unit-polynomial.
