diff --git a/auth_algo.cpp b/auth_algo.cpp
index 0bc2555..94a8c91 100644
--- a/auth_algo.cpp
+++ b/auth_algo.cpp
@@ -45,6 +45,40 @@
     return output;
 }
 
+std::vector<uint8_t> AlgoSHA256::generateHMAC(
+        const std::vector<uint8_t>& input) const
+{
+    std::vector<uint8_t> output(SHA256_DIGEST_LENGTH);
+    unsigned int mdLen = 0;
+
+    if (HMAC(EVP_sha256(), userKey.data(), userKey.size(), input.data(),
+             input.size(), output.data(), &mdLen) == NULL)
+    {
+        std::cerr << "Generate HMAC_SHA256 failed\n";
+        output.resize(0);
+    }
+
+    return output;
+}
+
+std::vector<uint8_t> AlgoSHA256::generateICV(
+        const std::vector<uint8_t>& input) const
+{
+    std::vector<uint8_t> output(SHA256_DIGEST_LENGTH);
+    unsigned int mdLen = 0;
+
+    if (HMAC(EVP_sha256(),
+             sessionIntegrityKey.data(), sessionIntegrityKey.size(),
+             input.data(), input.size(), output.data(), &mdLen) == NULL)
+    {
+        std::cerr << "Generate HMAC_SHA256_128 Integrity Check Value failed\n";
+        output.resize(0);
+    }
+    output.resize(integrityCheckValueLength);
+
+    return output;
+}
+
 } // namespace auth
 
 } // namespace cipher