feat: add components

components/component-shannonentropy-ex.js

@@ -0,0 +1,33 @@
+// http://blog.dkbza.org/2007/05/scanning-data-for-entropy-anomalies.html
+// https://github.com/dxa4481/truffleHog/blob/master/truffleHog.py
+
+var Math_log2 = Math.log2 || (x) => {
+    return Math.log(x) * Math.LOG2E;
+};
+
+exports.SHANNON_ENTROPY_BASE64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+exports.SHANNON_ENTROPY_HEX    = "1234567890abcdefABCDEF";
+
+exports.shannonEntropy = (data, charRange) => {
+    if (!data) {
+        return 0;
+    }
+    var lenOfData = data.length;
+    var charCodeCountMap = {};
+    for (var i = 0; i < data.length; i++) {
+        var charCode = data.charCodeAt(i);
+        charCodeCountMap[charCode] = charCodeCountMap[charCode] || 0;
+        charCodeCountMap[charCode] += 1;
+    }
+    var entropy = 0;
+    for (var i = 0; i < charRange.length; i++) {
+        var charCode = charRange.charCodeAt(i);
+        var charCodeCount = charCodeCountMap[charCode];
+        if (charCodeCount != null) {
+            var pCharCode = charCodeCount / lenOfData;
+            entropy += - pCharCode * Math_log2(pCharCode);
+        }
+    }
+    return entropy;
+};
+