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Protocol-Attacker is a framework for the creation of protocol analysis tools
There is a newer version: 1.1.2
/*
 * Protocol-Attacker - A Framework to create Protocol Analysis Tools
 *
 * Copyright 2023-2023 Ruhr University Bochum, Paderborn University, Technology Innovation Institute, and Hackmanit GmbH
 *
 * Licensed under Apache License, Version 2.0
 * http://www.apache.org/licenses/LICENSE-2.0.txt
 */
package de.rub.nds.protocol.crypto.ec;

import jakarta.xml.bind.annotation.XmlAccessType;
import jakarta.xml.bind.annotation.XmlAccessorType;
import java.io.Serializable;
import java.math.BigInteger;
import java.util.Objects;

/**
 * Can be used to store elements of a galois field.

 * The attribute data should contain some BigInteger representing the element.

 * The attribute modulus should contain some BigInteger that may be used to identify the field (and
 * for calculations).

 * All arithmetic operations are performed within the laws of the specified field.
 */
@XmlAccessorType(XmlAccessType.FIELD)
public abstract class FieldElement implements Serializable {

    /*
     * FieldElement objects are immutable. This should make deep copies in the methods of the EllipticCurve class
     * unnecessary.
     */
    private final BigInteger data;
    private final BigInteger modulus;

    public FieldElement(BigInteger data, BigInteger modulus) {
        this.data = data;
        this.modulus = modulus;
    }

    /**
     * Returns this + f.
     *
     * @param f An element of the field, which this is an element of.
     */
    public abstract FieldElement add(FieldElement f);

    /**
     * Returns this - f.
     *
     * @param f An element of the field, which this is an element of.
     */
    public FieldElement subtract(FieldElement f) {
        f = f.addInv();
        return add(f);
    }

    /**
     * Returns this * f.
     *
     * @param f An element of the field, which this is an element of.
     */
    public abstract FieldElement mult(FieldElement f);

    /**
     * Returns this * f^-1.
     *
     * @param f An element of the field, which this is an element of.
     */
    public FieldElement divide(FieldElement f) {
        f = f.multInv();
        return mult(f);
    }

    /** Returns -this. */
    public abstract FieldElement addInv();

    /** Returns this^-1. */
    public abstract FieldElement multInv();

    public BigInteger getData() {
        return this.data;
    }

    public BigInteger getModulus() {
        return this.modulus;
    }

    @Override
    public int hashCode() {
        int hash = 5;
        hash = 89 * hash + Objects.hashCode(this.data);
        hash = 89 * hash + Objects.hashCode(this.modulus);
        return hash;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final FieldElement other = (FieldElement) obj;
        if (!Objects.equals(this.data, other.data)) {
            return false;
        }
        if (!Objects.equals(this.modulus, other.modulus)) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return this.getData().toString() + " mod " + this.getModulus().toString();
    }
}