The frontend repo of this project

https://github.com/XenonHan/Shamirs-Secret-Sharing-Scheme-Web-App

Prerequisites

1. Java jdk 11
2. Eclipse IDE for Java EE Developers
3. Tomcat 9.0.39

Environment setting

1. project -> Properties -> Targeted Runtimes -> Apache Tomcat v9 -> Apply and close (this will add tomcat to our project)
2. Run (the green button) -> Run Configuration ->common -> Encoding -> Other & choose UTF-8 (support Chinese input in Eclipse)

Run

1. Maven -> Update Project Configuration
2. Run as -> maven install (optional)
3. Run as -> Run on Server

Test web page

1. Run our Angular frontend with this backend at the same time
2. go to localhost8080 and play around

Generate testing report

testing only, no report: mvn clean test
testing report only: mvn clean test site
coverage report only: mvn clean test jacoco:report
both report: mvn clean test site jacoco:report

Once you run the above command, you can see the two report:
\target\site\index.html is the testing report, \target\site\jacoco\index.html is the coverage report

Pseudocode

function encrypt(s, n, t)
  int[] coefficient
  int[] shares
  coefficients[0] = s
  for i = 1 to t
    coefficients[i] = randomNum(256)
  for i = 0 to n
    shares[i] = F(i, coefficients)
  return shares

function F(x, coefficients)
  int result = 1
  int val = 1
  for coefficient in coefficients
    result = result + coefficient* val
    val = val* x
  return result

function recover(shares, t)
  result = 0
  for i = 0 to t
    temp = shares[i].y
    for j = 0 to t
      if i != j
        fraction = shares[j].x / (shares[j].x - shares[i].x)
        temp = temp* fraction
    result = result + temp
  return result

function addOrMinus(a, b):
  return a ⊕ b

function multiplication(a, b)
  result = 0
  for i=7 down to 0
    if b[i] = 1
      result = result ⊕ a
    if a[0] = 0
      a = a << 1
    else
      a = (a << 1) ⊕ irreduciblePolynomials
  return result

function division(a, b)
  bInverse = power(b, 2^8-2)
  return multiplication(a, bInverse)

function power(a, idx)
  result = a
  for i=0 to idx-1
    result = multiplication(result, a)
  return result

// improved division
function division(a, b)
  return divisionTable[a][b]