Maven (#9)

src/main/java/de/caydenno1/xacrypto/hash/sha256/HMAC.java

@@ -0,0 +1,32 @@
+package de.caydenno1.xacrypto.hash.sha256;
+
+import de.caydenno1.xacrypto.misc.XACryptoException;
+
+import java.nio.charset.StandardCharsets;
+
+import static de.caydenno1.xacrypto.hash.sha256.Hex.hash;
+
+public class HMAC {
+    private HMAC(){}
+
+    public static byte[] hmac(byte[] key, byte[] mesg) throws XACryptoException {
+        byte[] k = (key.length > 64) ? hash(key) : key;
+
+        byte[] i = new byte[64];
+        byte[] o = new byte[64];
+        for (int l=0;l<64;l++) {
+            byte k_ = (l < k.length) ? k[l] : 0;
+            i[l] = (byte)(k_^0x36);
+            o[l] = (byte)(k_^0x5c);
+        }
+
+        byte[] in = new Digest().upd(i).upd(mesg).digest();
+
+        return new Digest().upd(o).upd(in).digest();
+    }
+
+    public static byte[] hmac(String key, String mesg) throws XACryptoException {
+        return hmac(key.getBytes(StandardCharsets.UTF_8),
+                mesg.getBytes(StandardCharsets.UTF_8));
+    }
+}