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# Group Theory

A

**group**is a set of elements $Z = \{a, b, c, ...\}$ and one binary operator $+$ that satisfies the following axioms:**Closure:**for any$a,b ∈ Z$, the element $a + b$ is in $Z$ .**Associativity:**for any $a,b,c ∈ Z$, $(a + b) + c = a + (b + c)$.**Identity:**$a + I = a$ , for all $a ∈ Z$.**Invertibility:**$a + (-a) = I$, for all $a ∈ Z$.

In addition to the above properties, if a group exhibits the commutative property of $a + b = b + a$, it is called an

**abelian group**.The elliptic curve used in Bitcoin is actually a mathematical group, that is

**finite**,**cyclic**,**abelian**, and has a**single-generator**point, defined over the**binary addition operator**. These properties form the bedrock for an efficient signature and verification mechanism in Bitcoin.A single-generator group contains an element $G ∈ Z$, called the

**generator point**, such that repeated additions of $G$ with itself can generate every element in $Z$.In fact, in prime order elliptic curves, any point can be a generator point.

$Z = \{G, 2G, 3G, 4G, ...\}$

Additionally, our group is cyclic, which means it has an order $n$, such that $nG = I$.

Let us now represent the generator point $G$in Python, used in Bitcoin.

# Generator point of the abelian group used in Bitcoin

G = Point(

x=0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798,

y=0x483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8,

curve=secp256k1

)

# Order of the group generated by G, such that nG = I

N = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141

Last modified 2mo ago