diff --git a/src/internal.c b/src/internal.c
index 4bd1f290..aeaaa46e 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -1014,10 +1014,11 @@ static int DoNewKeys(WOLFSSH* ssh, uint8_t* buf, uint32_t len, uint32_t* idx)
 }
 
 
-static int GenerateKey(uint8_t* key, uint32_t keySz, uint8_t keyId,
-                       const uint8_t* k, uint32_t kSz,
-                       const uint8_t* h, uint32_t hSz,
-                       const uint8_t* sessionId, uint32_t sessionIdSz)
+int GenerateKey(uint8_t hashId, uint8_t keyId,
+                uint8_t* key, uint32_t keySz,
+                const uint8_t* k, uint32_t kSz,
+                const uint8_t* h, uint32_t hSz,
+                const uint8_t* sessionId, uint32_t sessionIdSz)
 {
     uint32_t blocks, remainder;
     Sha sha;
@@ -1025,6 +1026,17 @@ static int GenerateKey(uint8_t* key, uint32_t keySz, uint8_t keyId,
     uint8_t pad = 0;
     uint8_t kSzFlat[LENGTH_SZ];
 
+    (void)hashId;
+
+    if (key == NULL || keySz == 0 ||
+        k == NULL || kSz == 0 ||
+        h == NULL || hSz == 0 ||
+        sessionId == NULL || sessionIdSz == 0) {
+
+        WLOG(WS_LOG_DEBUG, "GK: bad argument");
+        return WS_BAD_ARGUMENT;
+    }
+
     if (k[0] & 0x80) kPad = 1;
     c32toa(kSz + kPad, kSzFlat);
 
@@ -1085,18 +1097,52 @@ static int GenerateKeys(WOLFSSH* ssh)
     if (ssh == NULL)
         return WS_BAD_ARGUMENT;
 
-    GenerateKey(ssh->ivClient, ssh->ivClientSz, 'A', ssh->k, ssh->kSz,
-                ssh->h, ssh->hSz, ssh->sessionId, ssh->sessionIdSz);
-    GenerateKey(ssh->ivServer, ssh->ivServerSz, 'B', ssh->k, ssh->kSz,
-                ssh->h, ssh->hSz, ssh->sessionId, ssh->sessionIdSz);
-    GenerateKey(ssh->encKeyClient, ssh->encKeyClientSz, 'C', ssh->k, ssh->kSz,
-                ssh->h, ssh->hSz, ssh->sessionId, ssh->sessionIdSz);
-    GenerateKey(ssh->encKeyServer, ssh->encKeyServerSz, 'D', ssh->k, ssh->kSz,
-                ssh->h, ssh->hSz, ssh->sessionId, ssh->sessionIdSz);
-    GenerateKey(ssh->macKeyClient, ssh->macKeyClientSz, 'E', ssh->k, ssh->kSz,
-                ssh->h, ssh->hSz, ssh->sessionId, ssh->sessionIdSz);
-    GenerateKey(ssh->macKeyServer, ssh->macKeyServerSz, 'F', ssh->k, ssh->kSz,
-                ssh->h, ssh->hSz, ssh->sessionId, ssh->sessionIdSz);
+    GenerateKey(0, 'A',
+                ssh->ivClient, ssh->ivClientSz,
+                ssh->k, ssh->kSz, ssh->h, ssh->hSz,
+                ssh->sessionId, ssh->sessionIdSz);
+    GenerateKey(0, 'B',
+                ssh->ivServer, ssh->ivServerSz,
+                ssh->k, ssh->kSz, ssh->h, ssh->hSz,
+                ssh->sessionId, ssh->sessionIdSz);
+    GenerateKey(0, 'C',
+                ssh->encKeyClient, ssh->encKeyClientSz,
+                ssh->k, ssh->kSz, ssh->h, ssh->hSz,
+                ssh->sessionId, ssh->sessionIdSz);
+    GenerateKey(0, 'D',
+                ssh->encKeyServer, ssh->encKeyServerSz,
+                ssh->k, ssh->kSz, ssh->h, ssh->hSz,
+                ssh->sessionId, ssh->sessionIdSz);
+    GenerateKey(0, 'E',
+                ssh->macKeyClient, ssh->macKeyClientSz,
+                ssh->k, ssh->kSz, ssh->h, ssh->hSz,
+                ssh->sessionId, ssh->sessionIdSz);
+    GenerateKey(0, 'F',
+                ssh->macKeyServer, ssh->macKeyServerSz,
+                ssh->k, ssh->kSz, ssh->h, ssh->hSz,
+                ssh->sessionId, ssh->sessionIdSz);
+
+#ifdef SHOW_SECRETS
+    printf("\n** Showing Secrets **\nK:\n");
+    DumpOctetString(ssh->k, ssh->kSz);
+    printf("H:\n");
+    DumpOctetString(ssh->h, ssh->hSz);
+    printf("Session ID:\n");
+    DumpOctetString(ssh->sessionId, ssh->sessionIdSz);
+    printf("A:\n");
+    DumpOctetString(ssh->ivClient, ssh->ivClientSz);
+    printf("B:\n");
+    DumpOctetString(ssh->ivServer, ssh->ivServerSz);
+    printf("C:\n");
+    DumpOctetString(ssh->encKeyClient, ssh->encKeyClientSz);
+    printf("D:\n");
+    DumpOctetString(ssh->encKeyServer, ssh->encKeyServerSz);
+    printf("E:\n");
+    DumpOctetString(ssh->macKeyClient, ssh->macKeyClientSz);
+    printf("F:\n");
+    DumpOctetString(ssh->macKeyServer, ssh->macKeyServerSz);
+    printf("\n");
+#endif /* SHOW_SECRETS */
 
     return 0;
 }
diff --git a/src/ssh.c b/src/ssh.c
index 37d9bca1..d29d0d0f 100644
--- a/src/ssh.c
+++ b/src/ssh.c
@@ -592,3 +592,14 @@ int wolfSSH_CTX_UseCaCert_buffer(WOLFSSH_CTX* ctx,
 }
 
 
+int wolfSSH_KDF(uint8_t hashId, uint8_t keyId,
+                uint8_t* key, uint32_t keySz,
+                const uint8_t* k, uint32_t kSz,
+                const uint8_t* h, uint32_t hSz,
+                const uint8_t* sessionId, uint32_t sessionIdSz)
+{
+    WLOG(WS_LOG_DEBUG, "Entering wolfSSH_KDF()");
+    return GenerateKey(hashId, keyId, key, keySz, k, kSz, h, hSz,
+                       sessionId, sessionIdSz);
+}
+
diff --git a/test/unit.c b/test/unit.c
index 99a96ee6..acd4e3b0 100644
--- a/test/unit.c
+++ b/test/unit.c
@@ -20,7 +20,291 @@
  * Boston, MA  02110-1301, USA.
  */
 
-int main( void )
+
+#include <stdio.h>
+#include <wolfssh/ssh.h>
+
+
+static int test_KDF(void);
+static int ConvertHexToBin(const char* h1, uint8_t** b1, uint32_t* b1Sz,
+                           const char* h2, uint8_t** b2, uint32_t* b2Sz,
+                           const char* h3, uint8_t** b3, uint32_t* b3Sz,
+                           const char* h4, uint8_t** b4, uint32_t* b4Sz);
+static void FreeBins(uint8_t* b1, uint8_t* b2, uint8_t* b3, uint8_t* b4);
+static int Base16_Decode(const uint8_t* in, uint32_t inLen,
+                         uint8_t* out, uint32_t* outLen);
+
+
+int main(void)
 {
+    int testResult = 0, unitResult = 0;
+
+    unitResult = test_KDF();
+    printf("KDF: %s\n", (unitResult == 0 ? "SUCCESS" : "FAILED"));
+    testResult = testResult || unitResult;
+
+    return (testResult ? 1 : 0);
+}
+
+
+typedef struct {
+    uint8_t hashId;
+    uint8_t keyId;
+    const char* k;
+    const char* h;
+    const char* sessionId;
+    const char* expectedKey;
+} KdfTestVector;
+
+
+/** Test Vector Set #1 **/
+const char kdfTvSet1k[] =
+    "35618FD3AABF980A5F766408961600D4933C60DD7B22D69EEB4D7A987C938F6F"
+    "7BB2E60E0F638BB4289297B588E6109057325F010D021DF60EBF8BE67AD9C3E2"
+    "6376A326A16210C7AF07B3FE562B8DD1DCBECB17AA7BFAF38708B0136120B2FC"
+    "723E93EF4237AC3737BAE3A16EC03F605C7EEABFD526B38C826B506BBAECD2F7"
+    "9932F1371AEABFBEB4F8222313506677330C714A2A6FDC70CB859B581AA18625"
+    "ECCB6BA9DDEEAECF0E41D9E5076B899B477112E59DDADC4B4D9C13E9F07E1107"
+    "B560FEFDC146B8ED3E73441D05345031C35F9E6911B00319481D80015855BE4D"
+    "1C7D7ACC8579B1CC2E5F714109C0882C3B57529ABDA1F2255D2B27C4A83AE11E";
+const char kdfTvSet1h[]         = "40555741F6DE70CDC4E740104A97E75473F49064";
+const char kdfTvSet1sessionId[] = "40555741F6DE70CDC4E740104A97E75473F49064";
+const char kdfTvSet1a[]         = "B2EC4CF6943632C39972EE2801DC7393";
+const char kdfTvSet1b[]         = "BC92238B6FA69ECC10B2B013C2FC9785";
+const char kdfTvSet1c[]         = "9EF0E2053F66C56F3E4503DA1C2FBD6B";
+const char kdfTvSet1d[]         = "47C8395B08277020A0645DA3959FA1A9";
+const char kdfTvSet1e[]         = "EE436BFDABF9B0313224EC800E7390445E2F575E";
+const char kdfTvSet1f[]         = "FB9FDEEC78B0FB258F1A4F47F6BCE166680994BB";
+
+/** Test Vector Set #2 **/
+const char kdfTvSet2k[] =
+    "19FA2B7C7F4FE7DE61CDE17468C792CCEAB0E3F2CE37CDE2DAA0974BCDFFEDD4"
+    "A29415CDB330FA6A97ECA742359DC1223B581D8AC61B43CFFDF66D20952840B0"
+    "2593B48354E352E2A396BDF7F1C9D414FD31C2BF47E6EED306069C4F4F5F66C3"
+    "003A90E85412A1FBE89CDFB457CDA0D832E8DA701627366ADEC95B70E8A8B7BF"
+    "3F85775CCF36E40631B83B32CF643088F01A82C97C5C3A820EB4149F551CAF8C"
+    "C98EE6B3065E6152FF877823F7C618C1CD93CE26DB9FAAFED222F1C93E8F4068"
+    "BFDA4480432E14F98FFC821F05647693040B07D71DC273121D53866294434D46"
+    "0E95CFA4AB4414705BF1F8224655F907A418A6A893F2A71019225869CB7FE988";
+const char kdfTvSet2h[]         = "DFB748905CC8647684C3E0B7F26A3E8E7414AC51";
+const char kdfTvSet2sessionId[] = "DFB748905CC8647684C3E0B7F26A3E8E7414AC51";
+const char kdfTvSet2a[]         = "52EDBFD5E414A3CC6C7F7A0F4EA60503";
+const char kdfTvSet2b[]         = "926C6987696C5FFCC6511BFE34557878";
+const char kdfTvSet2c[]         = "CB6D56EC5B9AFECD326D544DA2D22DED";
+const char kdfTvSet2d[]         = "F712F6451F1BD6CE9BAA597AC87C5A24";
+const char kdfTvSet2e[]         = "E42FC62C76B76B37818F78292D3C2226D0264760";
+const char kdfTvSet2f[]         = "D14BE4DD0093A3E759580233C80BB8399CE4C4E7";
+
+static const KdfTestVector kdfTestVectors[] = {
+    {0, 'A', kdfTvSet1k, kdfTvSet1h, kdfTvSet1sessionId, kdfTvSet1a},
+    {0, 'B', kdfTvSet1k, kdfTvSet1h, kdfTvSet1sessionId, kdfTvSet1b},
+    {0, 'C', kdfTvSet1k, kdfTvSet1h, kdfTvSet1sessionId, kdfTvSet1c},
+    {0, 'D', kdfTvSet1k, kdfTvSet1h, kdfTvSet1sessionId, kdfTvSet1d},
+    {0, 'E', kdfTvSet1k, kdfTvSet1h, kdfTvSet1sessionId, kdfTvSet1e},
+    {0, 'F', kdfTvSet1k, kdfTvSet1h, kdfTvSet1sessionId, kdfTvSet1f},
+    {0, 'A', kdfTvSet2k, kdfTvSet2h, kdfTvSet2sessionId, kdfTvSet2a},
+    {0, 'B', kdfTvSet2k, kdfTvSet2h, kdfTvSet2sessionId, kdfTvSet2b},
+    {0, 'C', kdfTvSet2k, kdfTvSet2h, kdfTvSet2sessionId, kdfTvSet2c},
+    {0, 'D', kdfTvSet2k, kdfTvSet2h, kdfTvSet2sessionId, kdfTvSet2d},
+    {0, 'E', kdfTvSet2k, kdfTvSet2h, kdfTvSet2sessionId, kdfTvSet2e},
+    {0, 'F', kdfTvSet2k, kdfTvSet2h, kdfTvSet2sessionId, kdfTvSet2f}
+};
+
+int test_KDF(void)
+{
+    int result = 0;
+    uint32_t i;
+    uint32_t tc = sizeof(kdfTestVectors)/sizeof(KdfTestVector);
+    const KdfTestVector* tv = NULL;
+    uint8_t *k, *h, *sId, *eKey;
+    uint32_t kSz, hSz, sIdSz, eKeySz;
+    uint8_t cKey[20]; /* Greater of SHA_DIGEST_SIZE and AES_BLOCK_SIZE */
+    /* sId - Session ID, eKey - Expected Key, cKey - Calculated Key */
+
+    for (i = 0, tv = kdfTestVectors; i < tc; i++, tv++) {
+
+        result = ConvertHexToBin(tv->k, &k, &kSz,
+                                 tv->h, &h, &hSz,
+                                 tv->sessionId, &sId, &sIdSz,
+                                 tv->expectedKey, &eKey, &eKeySz);
+        if (result != 0) {
+            printf("KDF: Could not convert test vector %u.\n", i);
+            return -100;
+        }
+
+        result = wolfSSH_KDF(tv->hashId, tv->keyId, cKey, eKeySz,
+                             k, kSz, h, hSz, sId, sIdSz);
+
+        if (result != 0) {
+            printf("KDF: Could not derive key.\n");
+            result = -101;
+        }
+        else {
+            if (memcmp(cKey, eKey, eKeySz) != 0) {
+                printf("KDF: Calculated Key does not match Expected Key.\n");
+                result = -102;
+            }
+        }
+        
+        FreeBins(k, h, sId, eKey);
+
+        if (result != 0) break;
+    }
+
+    return result;
+}
+
+
+/* convert hex string to binary, store size, 0 success (free mem on failure) */
+int ConvertHexToBin(const char* h1, uint8_t** b1, uint32_t* b1Sz,
+                    const char* h2, uint8_t** b2, uint32_t* b2Sz,
+                    const char* h3, uint8_t** b3, uint32_t* b3Sz,
+                    const char* h4, uint8_t** b4, uint32_t* b4Sz)
+{
+    int ret;
+
+    /* b1 */
+    if (h1 && b1 && b1Sz) {
+        *b1Sz = (uint32_t)strlen(h1) / 2;
+        *b1   = (uint8_t*)malloc(*b1Sz);
+        if (*b1 == NULL)
+            return -1;
+        ret = Base16_Decode((const uint8_t*)h1, (uint32_t)strlen(h1),
+                            *b1, b1Sz);
+        if (ret != 0) {
+            FreeBins(*b1, NULL, NULL, NULL);
+            return -1;
+        }
+    }
+
+    /* b2 */
+    if (h2 && b2 && b2Sz) {
+        *b2Sz = (uint32_t)strlen(h2) / 2;
+        *b2   = (uint8_t*)malloc(*b2Sz);
+        if (*b2 == NULL) {
+            FreeBins(b1 ? *b1 : NULL, NULL, NULL, NULL);
+            return -1;
+        }
+        ret = Base16_Decode((const uint8_t*)h2, (uint32_t)strlen(h2),
+                            *b2, b2Sz);
+        if (ret != 0) {
+            FreeBins(b1 ? *b1 : NULL, *b2, NULL, NULL);
+            return -1;
+        }
+    }
+
+    /* b3 */
+    if (h3 && b3 && b3Sz) {
+        *b3Sz = (uint32_t)strlen(h3) / 2;
+        *b3   = (uint8_t*)malloc(*b3Sz);
+        if (*b3 == NULL) {
+            FreeBins(b1 ? *b1 : NULL, b2 ? *b2 : NULL, NULL, NULL);
+            return -1;
+        }
+        ret = Base16_Decode((const uint8_t*)h3, (uint32_t)strlen(h3),
+                            *b3, b3Sz);
+        if (ret != 0) {
+            FreeBins(b1 ? *b1 : NULL, b2 ? *b2 : NULL, *b3, NULL);
+            return -1;
+        }
+    }
+
+    /* b4 */
+    if (h4 && b4 && b4Sz) {
+        *b4Sz = (uint32_t)strlen(h4) / 2;
+        *b4   = (uint8_t*)malloc(*b4Sz);
+        if (*b4 == NULL) {
+            FreeBins(b1 ? *b1 : NULL, b2 ? *b2 : NULL, b3 ? *b3 : NULL, NULL);
+            return -1;
+        }
+        ret = Base16_Decode((const uint8_t*)h4, (uint32_t)strlen(h4),
+                            *b4, b4Sz);
+        if (ret != 0) {
+            FreeBins(b1 ? *b1 : NULL, b2 ? *b2 : NULL, b3 ? *b3 : NULL, *b4);
+            return -1;
+        }
+    }
+
     return 0;
 }
+
+
+void FreeBins(uint8_t* b1, uint8_t* b2, uint8_t* b3, uint8_t* b4)
+{
+    if (b1 != NULL) free(b1);
+    if (b2 != NULL) free(b2);
+    if (b3 != NULL) free(b3);
+    if (b4 != NULL) free(b4);
+}
+
+
+#define BAD 0xFF
+
+const uint8_t hexDecode[] =
+{
+    0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+    BAD, BAD, BAD, BAD, BAD, BAD, BAD,
+    10, 11, 12, 13, 14, 15,  /* upper case A-F */
+    BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
+    BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
+    BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
+    BAD, BAD,  /* G - ` */
+    10, 11, 12, 13, 14, 15   /* lower case a-f */
+};  /* A starts at 0x41 not 0x3A */
+
+
+static int Base16_Decode(const uint8_t* in, uint32_t inLen,
+                         uint8_t* out, uint32_t* outLen)
+{
+    uint32_t inIdx  = 0;
+    uint32_t outIdx = 0;
+
+    if (inLen == 1 && *outLen && in) {
+        uint8_t b = in[inIdx++] - 0x30;  /* 0 starts at 0x30 */
+
+        /* sanity check */
+        if (b >=  sizeof(hexDecode)/sizeof(hexDecode[0]))
+            return -1;
+
+        b  = hexDecode[b];
+
+        if (b == BAD)
+            return -1;
+        
+        out[outIdx++] = b;
+
+        *outLen = outIdx;
+        return 0;
+    }
+
+    if (inLen % 2)
+        return -1;
+
+    if (*outLen < (inLen / 2))
+        return -1;
+
+    while (inLen) {
+        uint8_t b  = in[inIdx++] - 0x30;  /* 0 starts at 0x30 */
+        uint8_t b2 = in[inIdx++] - 0x30;
+
+        /* sanity checks */
+        if (b >=  sizeof(hexDecode)/sizeof(hexDecode[0]))
+            return -1;
+        if (b2 >= sizeof(hexDecode)/sizeof(hexDecode[0]))
+            return -1;
+
+        b  = hexDecode[b];
+        b2 = hexDecode[b2];
+
+        if (b == BAD || b2 == BAD)
+            return -1;
+        
+        out[outIdx++] = (uint8_t)((b << 4) | b2);
+        inLen -= 2;
+    }
+
+    *outLen = outIdx;
+    return 0;
+}
+
+
diff --git a/wolfssh/internal.h b/wolfssh/internal.h
index 1b84ac41..92d6f5fd 100644
--- a/wolfssh/internal.h
+++ b/wolfssh/internal.h
@@ -274,6 +274,10 @@ WOLFSSH_LOCAL int SendUserAuthFailure(WOLFSSH*, uint8_t);
 WOLFSSH_LOCAL int SendUserAuthBanner(WOLFSSH*);
 WOLFSSH_LOCAL int SendChannelOpenConf(WOLFSSH* ssh);
 WOLFSSH_LOCAL int SendChannelData(WOLFSSH* ssh, uint32_t, uint8_t*, uint32_t);
+WOLFSSH_LOCAL int GenerateKey(uint8_t, uint8_t, uint8_t*, uint32_t,
+                              const uint8_t*, uint32_t,
+                              const uint8_t*, uint32_t,
+                              const uint8_t*, uint32_t);
 
 
 enum AcceptStates {
diff --git a/wolfssh/ssh.h b/wolfssh/ssh.h
index 8dc952ca..929393c1 100644
--- a/wolfssh/ssh.h
+++ b/wolfssh/ssh.h
@@ -87,6 +87,9 @@ WOLFSSH_API int wolfSSH_accept(WOLFSSH*);
 WOLFSSH_API int wolfSSH_stream_read(WOLFSSH*, uint8_t*, uint32_t);
 WOLFSSH_API int wolfSSH_stream_send(WOLFSSH*, uint8_t*, uint32_t);
 
+WOLFSSH_API int wolfSSH_KDF(uint8_t, uint8_t, uint8_t*, uint32_t,
+                const uint8_t*, uint32_t, const uint8_t*, uint32_t,
+                const uint8_t*, uint32_t);
 
 enum WS_EndpointTypes {
     WOLFSSH_ENDPOINT_SERVER,