diff --git a/integrity_algo.hpp b/integrity_algo.hpp
index 0d869c7..3e003b6 100644
--- a/integrity_algo.hpp
+++ b/integrity_algo.hpp
@@ -1,8 +1,8 @@
 #pragma once
 
-#include <openssl/sha.h>
 #include <array>
 #include <vector>
+#include "rmcp.hpp"
 
 namespace cipher
 {
@@ -10,25 +10,6 @@
 namespace integrity
 {
 
-using Key = std::array<uint8_t, SHA_DIGEST_LENGTH>;
-
-/*
- * RSP needs more keying material than can be provided by session integrity key
- * alone. As a result all keying material for the RSP integrity 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 integrity algorithm HMAC-SHA1-96, processing the following
- * constant will generate the required amount of keying material.
- */
-constexpr Key const1 = { 0x01, 0x01, 0x01, 0x01, 0x01,
-                         0x01, 0x01, 0x01, 0x01, 0x01,
-                         0x01, 0x01, 0x01, 0x01, 0x01,
-                         0x01, 0x01, 0x01, 0x01, 0x01
-                       };
-
 /**
  * @enum Integrity Algorithms
  *
@@ -61,13 +42,10 @@
         /**
          * @brief Constructor for Interface
          *
-         * @param[in] - Session Integrity Key to generate K1
-         * @param[in] - Additional keying material to generate K1
          * @param[in] - AuthCode length
          */
-        explicit Interface(const std::vector<uint8_t>& sik,
-                           const Key& addKey,
-                           size_t authLength);
+        explicit Interface(size_t authLength)
+            : authCodeLength(authLength) {}
 
         Interface() = delete;
         virtual ~Interface() = default;
@@ -122,6 +100,34 @@
             }
         }
 
+        /**
+         * @brief Generate additional keying material based on SIK
+         *
+         * @note
+         * The IPMI 2.0 spec only states that the additional keying material is
+         * generated by running HMAC(constN) using SIK as the key. It does not
+         * state whether this is the integrity algorithm or the authentication
+         * algorithm. Other implementations of the RMCP+ algorithm (ipmitool
+         * and ipmiutil) are not consistent on this matter. But it does not
+         * really matter because based on any of the defined cipher suites, the
+         * integrity and authentication algorithms are both based on the same
+         * digest method (integrity::Algorithms::HMAC_SHA1_96 uses SHA1 and
+         * rakp_auth::Algorithms::RAKP_HMAC_SHA1 uses SHA1). None of the
+         * defined cipher suites mix and match digests for integrity and
+         * authentication. Generating Kn belongs in either the integrity or
+         * authentication classes, so in this implementation, integrity has
+         * been chosen.
+         *
+         * @param[in] sik - session integrity key
+         * @param[in] data - 20-byte Const_n
+         *
+         * @return on success returns the Kn based on this integrity class
+         *
+         */
+        std::vector<uint8_t> virtual generateKn(
+                const std::vector<uint8_t>& sik,
+                const rmcp::Const_n& data) const = 0;
+
         /** @brief Authcode field
          *
          *  AuthCode field length varies based on the integrity algorithm, for
@@ -133,7 +139,7 @@
     protected:
 
         /** @brief K1 key used to generated the integrity data. */
-        Key K1;
+        std::vector<uint8_t> k1;
 };
 
 /**
@@ -157,8 +163,7 @@
          *
          * @param[in] - Session Integrity Key
          */
-        explicit AlgoSHA1(const std::vector<uint8_t>& sik) :
-            Interface(sik, const1, SHA1_96_AUTHCODE_LENGTH) {}
+        explicit AlgoSHA1(const std::vector<uint8_t>& sik);
 
         AlgoSHA1() = delete;
         ~AlgoSHA1() = default;
@@ -195,6 +200,19 @@
         std::vector<uint8_t> generateIntegrityData(
                 const std::vector<uint8_t>& packet) const override;
 
+        /**
+         * @brief Generate additional keying material based on SIK
+         *
+         * @param[in] sik - session integrity key
+         * @param[in] data - 20-byte Const_n
+         *
+         * @return on success returns the Kn based on HMAC-SHA1
+         *
+         */
+        std::vector<uint8_t> generateKn(
+                const std::vector<uint8_t>& sik,
+                const rmcp::Const_n& const_n) const;
+
     private:
         /**
          * @brief Generate HMAC based on HMAC-SHA1-96 algorithm