add sha1hmac

Author: Felix Robles

package-lock.json

@@ -0,0 +1,24 @@
+import { Digest } from "./Digest";
+/**
+ * A HMAC ( commonly referred to as a Hash ) (hash-based message authentication
+ * code) is a type of message authentication code (MAC) that uses a
+ * cryptographic hash function and a secret key. It may be used to verify data
+ * integrity and authentication of a message.
+ *
+ * Strontium assumes that HMAC functions will run on input that is entirely
+ * in memory. The interface does not currently support calculations against a
+ * stream.
+ *
+ * The exact nature or security properties of a given HMAC implementation
+ * will vary based on the implementing class.
+ */
+export abstract class HMAC extends Digest {
+  /**
+   * Create a new HMAC Encrypter.
+   *
+   * @param secretKey - The shared secret to use for encryption.
+   */
+  constructor(protected secretKey: Buffer) {
+    super()
+  }
+}

src/cryptography/abstract/HMAC.ts

@@ -0,0 +1,18 @@
+import { HMAC } from "../../abstract/HMAC"
+import { createHmac } from "crypto"
+
+/**
+ * The SHA1HMAC provides a HMAC implementation using SHA1 based on Node's
+ * OpenSSL.
+ *
+ * This implementation relies on the node crypto implementation and may vary based
+ * on the build flags of the underlying runtime.
+ */
+export class SHA1HMAC extends HMAC {
+  public async calculate(input: Buffer): Promise<Buffer> {
+    let hmacBuilder = createHmac("sha1", this.secretKey)
+    hmacBuilder.update(input)
+
+    return hmacBuilder.digest()
+  }
+}