+++ /dev/null
-<html>
-<head></head>
-<body>
-<script type="text/javascript">
-var prime = 1237;
-
-/* Split number into the shares */
-function split(number, available, needed) {
-
- var coef = [number, 166, 94], x, exp, c, accum, shares = [];
- for(c = 1, coef[0] = number; c < needed; c++) coef[c] = Math.floor(Math.random() * (prime - 1));
- for(x = 1; x <= available; x++) {
- /* coef = [1234, 166, 94] which is 1234x^0 + 166x^1 + 94x^2 */
- for(exp = 1, accum = coef[0]; exp < needed; exp++) accum = (accum + (coef[exp] * (Math.pow(x, exp) % prime) % prime)) % prime;
- /* Store values as (1, 132), (2, 66), (3, 188), (4, 241), (5, 225) (6, 140) */
- shares[x - 1] = [x, accum];
- }
- return shares;
-}
-
-/* Gives the decomposition of the gcd of a and b. Returns [x,y,z] such that x = gcd(a,b) and y*a + z*b = x */
-function gcdD(a,b) {
- if (b == 0) return [a, 1, 0];
- else {
- var n = Math.floor(a/b), c = a % b, r = gcdD(b,c);
- return [r[0], r[2], r[1]-r[2]*n];
- }
-}
-
-/* Gives the multiplicative inverse of k mod prime. In other words (k * modInverse(k)) % prime = 1 for all prime > k >= 1 */
-function modInverse(k) {
- k = k % prime;
- var r = (k < 0) ? -gcdD(prime,-k)[2] : gcdD(prime,k)[2];
- return (prime + r) % prime;
-}
-
-/* Join the shares into a number */
-function join(shares) {
- var accum, count, formula, startposition, nextposition, value, numerator, denominator;
- for(formula = accum = 0; formula < shares.length; formula++) {
- /* Multiply the numerator across the top and denominators across the bottom to do Lagrange's interpolation
- * Result is x0(2), x1(4), x2(5) -> -4*-5 and (2-4=-2)(2-5=-3), etc for l0, l1, l2...
- */
- for(count = 0, numerator = denominator = 1; count < shares.length; count++) {
- if(formula == count) continue; // If not the same value
- startposition = shares[formula][0];
- nextposition = shares[count][0];
- numerator = (numerator * -nextposition) % prime;
- denominator = (denominator * (startposition - nextposition)) % prime;
- }
- value = shares[formula][1];
- accum = (prime + accum + (value * numerator * modInverse(denominator))) % prime;
- }
- return accum;
-}
-
-var sh = split(1234, 6, 3) /* split the secret value 129 into 6 components - at least 3 of which will be needed to figure out the secret value */
-for (var i=0; i<sh.length; i++) alert(sh[i]);
-var newshares = [sh[1], sh[3], sh[4]]; /* pick any selection of 3 shared keys from sh */
-
-alert(join(newshares));
-
-</script>
-</body>
-</html>
\ No newline at end of file
projects / shamirs_secret_web_implementation.git / blobdiff