diff --git a/src/hotp.js b/src/hotp.js
index 0e18e79..3761ee7 100644
--- a/src/hotp.js
+++ b/src/hotp.js
@@ -22,7 +22,8 @@ export class HOTP extends OTP {
      * ```
      */
     at(count) {
-        return "HOTP.at";
+        let digit = super.generate_otp(count);
+        return digit;
     }
 
     /*＊
@@ -47,6 +48,12 @@ export class HOTP extends OTP {
      * ```
      */
     verify(otp, counter) {
-        return "HOTP.verify";
+        let otp_count = this.at(counter);
+
+        if (otp === otp_count) {
+            return true;
+        } else {
+            return false;
+        }
     }
 }
\ No newline at end of file
diff --git a/test/hotp_test.js b/test/hotp_test.js
index 2965ff8..8b5a18c 100644
--- a/test/hotp_test.js
+++ b/test/hotp_test.js
@@ -4,17 +4,18 @@ var assert = require('assert');
 describe('HOTP module test', function() {
 
     var HOTP = hotp.HOTP;
-    var a = new HOTP("BASE32_ENCODED_SECRET");
+    var a = new HOTP("J22U6B3WIWRRBTAV");
     
     describe('at() function', function() {
-        it("should print 'HOTP.at'", function() {
-            assert.equal("HOTP.at", a.at());
+        it("should return string", function() {
+            assert.equal("string", typeof(a.at(0)));
         });
     });
 
     describe('verify() function', function() {
-        it("should print 'HOTP.verify'", function() {
-            assert.equal("HOTP.verify", a.verify());
+        it("should verify the digit", function() {
+            assert.equal(true, a.verify(a.at(0), 0));
+            assert.equal(false, a.verify(a.at(0), 1));
         })
     })
 });
diff --git a/test/totp_test.js b/test/totp_test.js
index 253af40..9541ef5 100644
--- a/test/totp_test.js
+++ b/test/totp_test.js
@@ -13,7 +13,7 @@ describe('TOTP module test', function() {
     });
 
     describe('verify() function', function() {
-        it("should print 'TOTP.verify'", function() {
+        it("should verify the digit", function() {
             assert.equal(true, a.verify(a.now()));
         })
     })