diff --git a/crypt_algo.hpp b/crypt_algo.hpp
index ccef7d8..ca4dbca 100644
--- a/crypt_algo.hpp
+++ b/crypt_algo.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
-#include <openssl/sha.h>
 #include <array>
+#include <cstdint>
 #include <vector>
 
 namespace cipher
@@ -10,8 +10,6 @@
 namespace crypt
 {
 
-using key = std::array<uint8_t, SHA_DIGEST_LENGTH>;
-
 /**
  * @enum Confidentiality Algorithms
  *
@@ -42,11 +40,9 @@
     public:
         /**
          * @brief Constructor for Interface
-         *
-         * @param[in] - Session Integrity key to generate K2
-         * @param[in] - Additional keying material to generate K2
          */
-        explicit Interface(const std::vector<uint8_t>& sik, const key& addKey);
+        explicit Interface(const std::vector<uint8_t>& k2)
+            : k2(k2) {}
 
         Interface() = delete;
         virtual ~Interface() = default;
@@ -129,25 +125,6 @@
         static constexpr size_t AESCBC128BlockSize = 16;
 
         /**
-         * RSP needs more keying material than can be provided by session
-         * integrity key alone. As a result all keying material for the RSP
-         * confidentiality algorithms will be generated by processing a
-         * pre-defined set of constants using HMAC per [RFC2104], keyed by SIK.
-         * These constants are constructed using a hexadecimal octet value
-         * repeated up to the HMAC block size in length starting with the
-         * constant 01h. This mechanism can be used to derive up to 255
-         * HMAC-block-length pieces of keying material from a single SIK.For the
-         * mandatory confidentiality algorithm AES-CBC-128, processing the
-         * following constant will generate the required amount of keying
-         * material.
-         */
-        static constexpr key const2 = { 0x02, 0x02, 0x02, 0x02, 0x02,
-                                        0x02, 0x02, 0x02, 0x02, 0x02,
-                                        0x02, 0x02, 0x02, 0x02, 0x02,
-                                        0x02, 0x02, 0x02, 0x02, 0x02
-                                       };
-
-        /**
          * If confidentiality bytes are present, the value of the first byte is
          * one (01h). and all subsequent bytes shall have a monotonically
          * increasing value (e.g., 02h, 03h, 04h, etc). The receiver, as an
@@ -166,7 +143,7 @@
          *
          * @param[in] - Session Integrity key
          */
-        explicit AlgoAES128(const std::vector<uint8_t>& sik) : Interface(sik, const2) {}
+        explicit AlgoAES128(const std::vector<uint8_t>& k2) : Interface(k2) {}
 
         AlgoAES128() = delete;
         ~AlgoAES128() = default;