1 files changed, 68 insertions, 0 deletions
diff --git a/proper-random/javascript/rng.js b/proper-random/javascript/rng.js
new file mode 100644
index 0000000..03afc3a
--- /dev/null
+++ b/proper-random/javascript/rng.js
@@ -0,0 +1,68 @@
+// Random number generator - requires a PRNG backend, e.g. prng4.js
+
+// For best results, put code like
+// <body onClick='rng_seed_time();' onKeyPress='rng_seed_time();'>
+// in your main HTML document.
+
+var rng_state;
+var rng_pool;
+var rng_pptr;
+
+// Mix in a 32-bit integer into the pool
+function rng_seed_int(x) {
+  rng_pool[rng_pptr++] ^= x & 255;
+  rng_pool[rng_pptr++] ^= (x >> 8) & 255;
+  rng_pool[rng_pptr++] ^= (x >> 16) & 255;
+  rng_pool[rng_pptr++] ^= (x >> 24) & 255;
+  if(rng_pptr >= rng_psize) rng_pptr -= rng_psize;
+}
+
+// Mix in the current time (w/milliseconds) into the pool
+function rng_seed_time() {
+  rng_seed_int(new Date().getTime());
+}
+
+// Initialize the pool with junk if needed.
+if(rng_pool == null) {
+  rng_pool = new Array();
+  rng_pptr = 0;
+  var t;
+  if(navigator.appName == "Netscape" && navigator.appVersion < "5" && window.crypto) {
+    // Extract entropy (256 bits) from NS4 RNG if available
+    var z = window.crypto.random(32);
+    for(t = 0; t < z.length; ++t)
+      rng_pool[rng_pptr++] = z.charCodeAt(t) & 255;
+  }  
+  while(rng_pptr < rng_psize) {  // extract some randomness from Math.random()
+    t = Math.floor(65536 * Math.random());
+    rng_pool[rng_pptr++] = t >>> 8;
+    rng_pool[rng_pptr++] = t & 255;
+  }
+  rng_pptr = 0;
+  rng_seed_time();
+  //rng_seed_int(window.screenX);
+  //rng_seed_int(window.screenY);
+}
+
+function rng_get_byte() {
+  if(rng_state == null) {
+    rng_seed_time();
+    rng_state = prng_newstate();
+    rng_state.init(rng_pool);
+    for(rng_pptr = 0; rng_pptr < rng_pool.length; ++rng_pptr)
+      rng_pool[rng_pptr] = 0;
+    rng_pptr = 0;
+    //rng_pool = null;
+  }
+  // TODO: allow reseeding after first request
+  return rng_state.next();
+}
+
+function rng_get_bytes(ba) {
+  var i;
+  for(i = 0; i < ba.length; ++i) ba[i] = rng_get_byte();
+}
+
+function SecureRandom() {}
+
+SecureRandom.prototype.nextBytes = rng_get_bytes;