feat: Replace aCAPTCHA with official ALTCHA (altcha.org) Proof-of-Work web component widget

frontend/node_modules/hash-wasm/lib/hmac.ts

@@ -0,0 +1,86 @@
+import type { IHasher } from "./WASMInterface";
+import { type IDataType, getUInt8Buffer } from "./util";
+
+function calculateKeyBuffer(hasher: IHasher, key: IDataType): Uint8Array {
+	const { blockSize } = hasher;
+
+	const buf = getUInt8Buffer(key);
+
+	if (buf.length > blockSize) {
+		hasher.update(buf);
+		const uintArr = hasher.digest("binary");
+		hasher.init();
+		return uintArr;
+	}
+
+	return new Uint8Array(buf.buffer, buf.byteOffset, buf.length);
+}
+
+function calculateHmac(hasher: IHasher, key: IDataType): IHasher {
+	hasher.init();
+
+	const { blockSize } = hasher;
+	const keyBuf = calculateKeyBuffer(hasher, key);
+	const keyBuffer = new Uint8Array(blockSize);
+	keyBuffer.set(keyBuf);
+
+	const opad = new Uint8Array(blockSize);
+
+	for (let i = 0; i < blockSize; i++) {
+		const v = keyBuffer[i];
+		opad[i] = v ^ 0x5c;
+		keyBuffer[i] = v ^ 0x36;
+	}
+
+	hasher.update(keyBuffer);
+
+	const obj: IHasher = {
+		init: () => {
+			hasher.init();
+			hasher.update(keyBuffer);
+			return obj;
+		},
+
+		update: (data: IDataType) => {
+			hasher.update(data);
+			return obj;
+		},
+
+		digest: ((outputType) => {
+			const uintArr = hasher.digest("binary");
+			hasher.init();
+			hasher.update(opad);
+			hasher.update(uintArr);
+			return hasher.digest(outputType);
+			// biome-ignore lint/suspicious/noExplicitAny: Conflict with IHasher type
+		}) as any,
+		save: () => {
+			throw new Error("save() not supported");
+		},
+		load: () => {
+			throw new Error("load() not supported");
+		},
+
+		blockSize: hasher.blockSize,
+		digestSize: hasher.digestSize,
+	};
+	return obj;
+}
+
+/**
+ * Calculates HMAC hash
+ * @param hash Hash algorithm to use. It has to be the return value of a function like createSHA1()
+ * @param key Key (string, Buffer or TypedArray)
+ */
+export function createHMAC(
+	hash: Promise<IHasher>,
+	key: IDataType,
+): Promise<IHasher> {
+	if (!hash || !hash.then) {
+		throw new Error(
+			'Invalid hash function is provided! Usage: createHMAC(createMD5(), "key").',
+		);
+	}
+
+	return hash.then((hasher) => calculateHmac(hasher, key));
+}