feat: add HMAC algorithm

deps.ts

@@ -0,0 +1,2 @@
+export { createHash } from "https://deno.land/std@0.90.0/hash/mod.ts";
+export type { SupportedAlgorithm } from "https://deno.land/std@0.90.0/hash/mod.ts";

dev_deps.ts

@@ -7,3 +7,4 @@ export {
   assertThrows,
 } from "https://deno.land/std@0.90.0/testing/asserts.ts";
 export { parse as parseArgs } from "https://deno.land/std@0.90.0/flags/mod.ts";
+export { encodeToString as encodeToHex } from "https://deno.land/x/std@0.90.0/encoding/hex.ts";

hmac.ts

@@ -0,0 +1 @@
+export { hmac } from "./src/hmac/mod.ts";

src/hmac/mod.ts

@@ -0,0 +1,66 @@
+import { createHash, SupportedAlgorithm } from "../../deps.ts";
+
+export type { SupportedAlgorithm };
+
+const blockSizes: Record<SupportedAlgorithm, number> = {
+  "sha3-512": 72,
+  "sha3-384": 48,
+  "sha3-256": 136,
+  "sha3-224": 144,
+  sha512: 128,
+  sha384: 128,
+  sha256: 64,
+  sha224: 64,
+  sha1: 64,
+  md5: 64,
+  md4: 64,
+  md2: 16,
+  ripemd320: 64,
+  ripemd160: 64,
+  keccak512: 72,
+  keccak384: 48,
+  keccak256: 136,
+  keccak224: 144,
+};
+
+export function hmac(
+  hash: SupportedAlgorithm,
+  key: Uint8Array,
+  data: Uint8Array,
+): Uint8Array {
+  const blockSize = blockSizes[hash];
+
+  if (key.length > blockSize) {
+    key = new Uint8Array(createHash(hash).update(key).digest());
+  }
+
+  if (key.length < blockSize) {
+    const keylong = new Uint8Array(blockSize);
+    keylong.set(key, 0);
+    key = keylong;
+  }
+
+  const opad = new Uint8Array(blockSize);
+  const ipad = new Uint8Array(blockSize);
+
+  for (let i = 0; i < blockSize; i++) {
+    opad[i] = key[i] ^ 0x5c;
+    ipad[i] = key[i] ^ 0x36;
+  }
+
+  return new Uint8Array(
+    createHash(hash).update(
+      concat(
+        opad,
+        new Uint8Array(createHash(hash).update(concat(ipad, data)).digest()),
+      ),
+    ).digest(),
+  );
+}
+
+function concat(a: Uint8Array, b: Uint8Array) {
+  const arr = new Uint8Array(a.length + b.length);
+  arr.set(a, 0);
+  arr.set(b, a.length);
+  return arr;
+}

tests/hmac.test.ts

@@ -0,0 +1,27 @@
+import { hmac } from "../hmac.ts";
+import { assertEquals, encodeToHex } from "../dev_deps.ts";
+
+const encoder = new TextEncoder();
+const key = encoder.encode("secret");
+const data = encoder.encode("hello world!");
+
+Deno.test("HMAC-SHA1", () => {
+  assertEquals(
+    encodeToHex(hmac("sha1", key, data)),
+    "a4df5f9d237ab0ca3241f042bcf6059a4ef491c4",
+  );
+});
+
+Deno.test("HMAC-SHA256", () => {
+  assertEquals(
+    encodeToHex(hmac("sha256", key, data)),
+    "72069731bf291b463aecb218bc227abce3d403d76da67faef2d48d3cb43b2f54",
+  );
+});
+
+Deno.test("HMAC-SHA512", () => {
+  assertEquals(
+    encodeToHex(hmac("sha512", key, data)),
+    "563069fb7c8512ffe6ced927289ac5e6f30a360c1099c61b62e3a91636a2563c95524ab5a0f4fe41f86e990a9f732dbf60d4f6c85761dafbd4953c24c758f936",
+  );
+});