index.js

@@ -158,6 +158,71 @@ Utils.prototype.Log = function Log(options) {
 	}
 };
 
+/**
+ * JS Implementation of MurmurHash3 (r136) (as of May 20, 2011)
+ *
+ * @author <a href="mailto:gary.court@gmail.com">Gary Court</a>
+ * @see http://github.com/garycourt/murmurhash-js
+ * @author <a href="mailto:aappleby@gmail.com">Austin Appleby</a>
+ * @see http://sites.google.com/site/murmurhash/
+ *
+ * @param {string} key ASCII only
+ * @param {number} seed Positive integer only
+ * @return {number} 32-bit positive integer hash
+ */
+
+function murmurhash3_32_gc(key, seed) {
+	let remainder; let bytes; let h1; let h1b; let c1; let c2; let k1; let i;
+
+	remainder = key.length & 3; // Same as key.length % 4
+	bytes = key.length - remainder;
+	h1 = seed;
+	c1 = 0xcc9e2d51;
+	c2 = 0x1b873593;
+	i = 0;
+
+	while (i < bytes) {
+		k1 =
+			((key.charCodeAt(i) & 0xff)) |
+			((key.charCodeAt(++i) & 0xff) << 8) |
+			((key.charCodeAt(++i) & 0xff) << 16) |
+			((key.charCodeAt(++i) & 0xff) << 24);
+		++i;
+
+		k1 = ((((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16))) & 0xffffffff;
+		k1 = (k1 << 15) | (k1 >>> 17);
+		k1 = ((((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16))) & 0xffffffff;
+
+		h1 ^= k1;
+		h1 = (h1 << 13) | (h1 >>> 19);
+		h1b = ((((h1 & 0xffff) * 5) + ((((h1 >>> 16) * 5) & 0xffff) << 16))) & 0xffffffff;
+		h1 = (((h1b & 0xffff) + 0x6b64) + ((((h1b >>> 16) + 0xe654) & 0xffff) << 16));
+	}
+
+	k1 = 0;
+
+	switch (remainder) {
+	case 3: k1 ^= (key.charCodeAt(i + 2) & 0xff) << 16;
+	case 2: k1 ^= (key.charCodeAt(i + 1) & 0xff) << 8;
+	case 1: k1 ^= (key.charCodeAt(i) & 0xff);
+
+		k1 = (((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16)) & 0xffffffff;
+		k1 = (k1 << 15) | (k1 >>> 17);
+		k1 = (((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16)) & 0xffffffff;
+		h1 ^= k1;
+	}
+
+	h1 ^= key.length;
+
+	h1 ^= h1 >>> 16;
+	h1 = (((h1 & 0xffff) * 0x85ebca6b) + ((((h1 >>> 16) * 0x85ebca6b) & 0xffff) << 16)) & 0xffffffff;
+	h1 ^= h1 >>> 13;
+	h1 = ((((h1 & 0xffff) * 0xc2b2ae35) + ((((h1 >>> 16) * 0xc2b2ae35) & 0xffff) << 16))) & 0xffffffff;
+	h1 ^= h1 >>> 16;
+
+	return h1 >>> 0;
+}
+
 /**
  * Hash string into another string (A-Z, 0-9)
  *
@@ -171,26 +236,11 @@ Utils.prototype.hashStringToString = function hashStringToString(str, length) {
 	const base = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
 	const resultIndices = new Array(length);
 
-	// Generate an index salt so that similar input strings will give different result strings
-	let indexSalt = 0;
-	for (let i = 0; i < str.length; i++) {
-		indexSalt += (1 << str.charCodeAt(i)) >>> 0;
-	}
-
-	if (str.length >= length) {
-		// Input string is longer or same length as desired result string length
-		for (let i = 0; i < str.length; ++i) {
-			const resultIndex = i % length;
-			const valueIndex = Math.abs(((resultIndices[resultIndex] ? resultIndices[resultIndex] : 0) + ((1 << str.charCodeAt(i))) + indexSalt + i) % base.length);
-			resultIndices[resultIndex] = valueIndex;
-		}
-	} else {
-		// Result string string is longer than the input string
-		for (let i = 0; i < resultIndices.length; ++i) {
-			const resultIndex = i;
-			const valueIndex = Math.abs((((1 << str.charCodeAt(i % str.length)) * i) + indexSalt) % base.length);
-			resultIndices[resultIndex] = valueIndex;
-		}
+	for (let i = 0; i < resultIndices.length; ++i) {
+		const indexHash = murmurhash3_32_gc(str, i);
+
+		const valueIndex = Math.abs(indexHash % base.length);
+		resultIndices[i] = valueIndex;
 	}
 
 	const result = resultIndices.map(x => base[x]).join('');

package.json

@@ -1,6 +1,6 @@
 {
   "name": "larvitutils",
-  "version": "2.3.2",
+  "version": "2.3.3",
   "description": "Misc utils",
   "main": "index.js",
   "devDependencies": {

test/hashStringToString.js

@@ -47,3 +47,11 @@ test('hashStringToString() - Hash string where all characters are the same shoul
 
 	t.end();
 });
+
+test('hashStringToString() - Two similar strings should not give the same hash (bug fixed so using exact strings that caused trouble here)', t => {
+	const str1 = 'L266' + '9560-13';
+	const str2 = 'L266' + '9500-13';
+
+	t.notEqual(utils.hashStringToString(str1, 6), utils.hashStringToString(str2, 6));
+	t.end();
+});