1 files changed, 59 insertions, 0 deletions
diff --git a/src/api/util/utility/passwordStrength.ts b/src/api/util/utility/passwordStrength.ts
new file mode 100644
index 00000000..8eca63b8
--- /dev/null
+++ b/src/api/util/utility/passwordStrength.ts
@@ -0,0 +1,59 @@
+import { Config } from "@fosscord/util";
+
+const reNUMBER = /[0-9]/g;
+const reUPPERCASELETTER = /[A-Z]/g;
+const reSYMBOLS = /[A-Z,a-z,0-9]/g;
+
+const blocklist: string[] = []; // TODO: update ones passwordblocklist is stored in db
+/*
+ * https://en.wikipedia.org/wiki/Password_policy
+ * password must meet following criteria, to be perfect:
+ *  - min <n> chars
+ *  - min <n> numbers
+ *  - min <n> symbols
+ *  - min <n> uppercase chars
+ *  - shannon entropy folded into [0, 1) interval
+ *
+ * Returns: 0 > pw > 1
+ */
+export function checkPassword(password: string): number {
+	const { minLength, minNumbers, minUpperCase, minSymbols } = Config.get().register.password;
+	let strength = 0;
+
+	// checks for total password len
+	if (password.length >= minLength - 1) {
+		strength += 0.05;
+	}
+
+	// checks for amount of Numbers
+	if (password.count(reNUMBER) >= minNumbers - 1) {
+		strength += 0.05;
+	}
+
+	// checks for amount of Uppercase Letters
+	if (password.count(reUPPERCASELETTER) >= minUpperCase - 1) {
+		strength += 0.05;
+	}
+
+	// checks for amount of symbols
+	if (password.replace(reSYMBOLS, "").length >= minSymbols - 1) {
+		strength += 0.05;
+	}
+
+	// checks if password only consists of numbers or only consists of chars
+	if (password.length == password.count(reNUMBER) || password.length === password.count(reUPPERCASELETTER)) {
+		strength = 0;
+	}
+	
+	let entropyMap: { [key: string]: number } = {};
+	for (let i = 0; i < password.length; i++) {
+		if (entropyMap[password[i]]) entropyMap[password[i]]++;
+		else entropyMap[password[i]] = 1;
+	}
+	
+	let entropies = Object.values(entropyMap);
+	
+	entropies.map(x => (x / entropyMap.length));
+	strength += entropies.reduceRight((a: number, x: number) => a - (x * Math.log2(x))) / Math.log2(password.length);	
+	return strength;
+}