|
| 1 | + |
| 2 | +// variables |
| 3 | + |
| 4 | +var pInput = document.getElementById("p"); |
| 5 | +var qInput = document.getElementById("q"); |
| 6 | +var eInput = document.getElementById("e"); |
| 7 | +var dInput = document.getElementById("d"); |
| 8 | +var pTextInput = document.getElementById("input"); |
| 9 | +var cTextInput = document.getElementById("output"); |
| 10 | +var genBtn = document.getElementById("genBtn"); |
| 11 | +var op = document.getElementById("op"); |
| 12 | +var opBtn = document.getElementById("opBtn"); |
| 13 | + |
| 14 | +var p = 0; |
| 15 | +var q = 0; |
| 16 | +var n = 0; |
| 17 | +var phi = 0; |
| 18 | +var e = 0; |
| 19 | +var d = 0; |
| 20 | +var isEncryption = true; |
| 21 | + |
| 22 | + |
| 23 | + |
| 24 | + |
| 25 | + |
| 26 | + |
| 27 | + |
| 28 | +//setters |
| 29 | +function setP(val) { |
| 30 | + p = val; |
| 31 | +} |
| 32 | + |
| 33 | +function setQ(val) { |
| 34 | + q = val; |
| 35 | +} |
| 36 | + |
| 37 | +function setN(val) { |
| 38 | + n = val; |
| 39 | +} |
| 40 | + |
| 41 | +function setPhi(val) { |
| 42 | + phi = val; |
| 43 | +} |
| 44 | + |
| 45 | +function setE(val) { |
| 46 | + e = val; |
| 47 | +} |
| 48 | + |
| 49 | +function setD(val) { |
| 50 | + d = val; |
| 51 | +} |
| 52 | + |
| 53 | + |
| 54 | +//event listeners |
| 55 | + |
| 56 | +genBtn.addEventListener("click", function () { |
| 57 | + p = parseInt(pInput.value); |
| 58 | + q = parseInt(qInput.value); |
| 59 | + generateKeys(); |
| 60 | + eInput.value = "("+e+","+n+")"; |
| 61 | + dInput.value = "("+d+","+n+")"; |
| 62 | +}); |
| 63 | + |
| 64 | +op.addEventListener("click", function (event) { |
| 65 | + if(event.target.value == "encrypt"){ |
| 66 | + isEncryption = true; |
| 67 | + document.getElementById("opTitle").innerHTML = "Encrypt"; |
| 68 | + opBtn.innerHTML = "Encrypt"; |
| 69 | + document.getElementById("result").innerHTML = "Cipher text = "; |
| 70 | + }else{ |
| 71 | + isEncryption = false; |
| 72 | + document.getElementById("opTitle").innerHTML = "Decrypt"; |
| 73 | + opBtn.innerHTML = "Decrypt"; |
| 74 | + document.getElementById("result").innerHTML = "Plain text = "; |
| 75 | + } |
| 76 | +}); |
| 77 | + |
| 78 | +opBtn.addEventListener("click", function () { |
| 79 | + if(isEncryption){ |
| 80 | + encrypt(); |
| 81 | + }else{ |
| 82 | + decrypt(); |
| 83 | + } |
| 84 | +}); |
| 85 | + |
| 86 | + |
| 87 | +//checkprime - function to check if a number is prime |
| 88 | +function checkprime(n) { |
| 89 | + if (n === 2) { |
| 90 | + return true; |
| 91 | + } else if (n % 2 === 0 || n === 1 || n === 0) { |
| 92 | + return false; |
| 93 | + } else { |
| 94 | + for (let i = 3; i <= Math.sqrt(n); i += 2) { |
| 95 | + if (n % i === 0) { |
| 96 | + return false; |
| 97 | + } |
| 98 | + } |
| 99 | + return true; |
| 100 | + } |
| 101 | +} |
| 102 | + |
| 103 | +//gcd - function to find gcd of two numbers |
| 104 | +function gcd(a, b) { |
| 105 | + if (b === 0) { |
| 106 | + return a; |
| 107 | + } else { |
| 108 | + return gcd(b, a % b); |
| 109 | + } |
| 110 | +} |
| 111 | + |
| 112 | + |
| 113 | + |
| 114 | +// generateKeys - function to generate keys using p and q |
| 115 | + |
| 116 | +function generateKeys() { |
| 117 | + if (p && q) { |
| 118 | + if (checkprime(p) && checkprime(q)) { |
| 119 | + let nz = p * q; // n = p*q |
| 120 | + let phiz = (p - 1) * (q - 1); // phi = (p-1)*(q-1) |
| 121 | + setN(nz); |
| 122 | + setPhi((p - 1) * (q - 1)); |
| 123 | + |
| 124 | + let ez = 2; // e = 2 |
| 125 | + while (ez < phiz) { |
| 126 | + if (gcd(ez, phiz) === 1) { |
| 127 | + // e and phi must be coprime |
| 128 | + break; |
| 129 | + } else { |
| 130 | + ez++; |
| 131 | + } |
| 132 | + } |
| 133 | + |
| 134 | + setE(ez); |
| 135 | + |
| 136 | + let dz = 1; |
| 137 | + while (dz < phiz) { |
| 138 | + if ((ez * dz) % phiz === 1) { |
| 139 | + // d = (1/e)mod(phi) |
| 140 | + break; |
| 141 | + } else { |
| 142 | + dz++; |
| 143 | + } |
| 144 | + } |
| 145 | + setD(dz); |
| 146 | + console.log("p: " + p); |
| 147 | + console.log("q: " + q); |
| 148 | + console.log("n: " + n); |
| 149 | + console.log("phi: " + phi); |
| 150 | + console.log("e: " + e); |
| 151 | + console.log("d: " + d); |
| 152 | + |
| 153 | + } else { |
| 154 | + alert("p and q must be prime"); |
| 155 | + } |
| 156 | + } else { |
| 157 | + alert("p and q cannot be empty"); |
| 158 | + } |
| 159 | +} |
| 160 | + |
| 161 | + |
| 162 | + |
| 163 | +//binarymod - function to calculate (b^e)mod(m) |
| 164 | +function binarymod(b, e, m) { |
| 165 | + let r = 1; |
| 166 | + b = b % m; |
| 167 | + while (e > 0) { |
| 168 | + if (e % 2 == 1) { |
| 169 | + r = (r * b) % m; |
| 170 | + } |
| 171 | + e = Math.floor(e / 2); |
| 172 | + b = (b * b) % m; |
| 173 | + } |
| 174 | + return r; |
| 175 | +} |
| 176 | + |
| 177 | + |
| 178 | +function encrypt() { |
| 179 | + console.log("encrypt") |
| 180 | + let m = parseInt(pTextInput.value); |
| 181 | + let c = binarymod(m, e, n); |
| 182 | + cTextInput.value = c; |
| 183 | +} |
| 184 | + |
| 185 | +function decrypt() { |
| 186 | + let c = parseInt(pTextInput.value); |
| 187 | + let m = binarymod(c, d, n); |
| 188 | + console.log(c,m) |
| 189 | + cTextInput.value = m; |
| 190 | +} |
0 commit comments