Merge pull request #651 from Kr0emer/fix/bug-007-isprobableprime-negative

fix(jsbn2): reject non-positive values in primality checks

Author: kjur

ext/jsbn2.js

@@ -558,6 +558,7 @@ var lplim = (1<<26)/lowprimes[lowprimes.length-1];
 
 // (public) test primality with certainty >= 1-.5^t
 function bnIsProbablePrime(t) {
+  if(this.signum() <= 0) return false;
   var i, x = this.abs();
   if(x.t == 1 && x[0] <= lowprimes[lowprimes.length-1]) {
     for(i = 0; i < lowprimes.length; ++i)
@@ -577,6 +578,7 @@ function bnIsProbablePrime(t) {
 
 // (protected) true if probably prime (HAC 4.24, Miller-Rabin)
 function bnpMillerRabin(t) {
+  if(this.signum() <= 0) return false;
   var n1 = this.subtract(BigInteger.ONE);
   var k = n1.getLowestSetBit();
   if(k <= 0) return false;

test/qunit-do-crypto.html

@@ -248,6 +248,17 @@
   equal(n, 100, "100 times success:" + n0 + ":" + n1 + ":" + n2 + ":" + n3);
 });
 
+test("BigInteger.isProbablePrime rejects negative values", function() {
+  equal(new BigInteger("-2", 10).isProbablePrime(20), false, "-2 is not prime");
+  equal(new BigInteger("-7", 10).isProbablePrime(20), false, "-7 is not prime");
+  equal(new BigInteger("-97", 10).isProbablePrime(20), false, "-97 is not prime");
+});
+
+test("BigInteger.isProbablePrime control values", function() {
+  equal(new BigInteger("7", 10).isProbablePrime(20), true, "7 is prime");
+  equal(new BigInteger("4", 10).isProbablePrime(20), false, "4 is composite");
+});
+
 test("RSASetPublic rejects zero modulus", function() {
   throws(function() {
     var pub = new RSAKey();