diff --git a/include/crypto_error.h b/include/crypto_error.h
index b9374aff..42094721 100644
--- a/include/crypto_error.h
+++ b/include/crypto_error.h
@@ -89,5 +89,6 @@
 #define CRYPTO_LIB_ERR_NO_ECS_SET_FOR_ENCRYPTION_MODE (-36)
 #define CRYPTO_LIB_ERR_IV_LEN_SHORTER_THAN_SEC_HEADER_LENGTH (-37)
 #define CRYPTO_LIB_ERR_ARSN_LEN_SHORTER_THAN_SEC_HEADER_LENGTH (-38)
+#define CRYPTO_LIB_ERR_FRAME_COUNTER_DOESNT_MATCH_SA (-39)
 
 #endif //_crypto_error_h_
diff --git a/src/src_main/crypto_tc.c b/src/src_main/crypto_tc.c
index fb372707..62ec36aa 100644
--- a/src/src_main/crypto_tc.c
+++ b/src/src_main/crypto_tc.c
@@ -23,8 +23,9 @@
 
 #include <string.h> // memcpy
 
-/* Helper validate SA function */
+/* Helper functions */
 static int32_t crypto_tc_validate_sa(SecurityAssociation_t *sa);
+static int32_t crypto_handle_incrementing_nontransmitted_counter(uint8_t* dest, uint8_t* src, int src_full_len,int transmitted_len, int window);
 
 /**
  * @brief Function: Crypto_TC_ApplySecurity
@@ -809,21 +810,53 @@ int32_t Crypto_TC_ProcessSecurity(uint8_t* ingest, int *len_ingest, TC_t* tc_sdl
         }
     }
 
-    // Retrieve non-transmitted portion of IV from SA (if applicable)
-    memcpy(tc_sdls_processed_frame->tc_sec_header.iv, sa_ptr->iv, sa_ptr->iv_len-sa_ptr->shivf_len);
-    // Parse transmitted portion of IV
+    // Parse transmitted portion of IV from received frame (Will be Whole IV if iv_len==shivf_len)
     memcpy((tc_sdls_processed_frame->tc_sec_header.iv+(sa_ptr->iv_len-sa_ptr->shivf_len)), &(ingest[TC_FRAME_HEADER_SIZE + segment_hdr_len + SPI_LEN]),
            sa_ptr->shivf_len);
+
+    // Handle non-transmitted IV increment case (transmitted-portion roll-over)
+    if(sa_ptr->shivf_len < sa_ptr->iv_len &&
+        crypto_config->ignore_anti_replay==TC_IGNORE_ANTI_REPLAY_FALSE &&
+        crypto_config->crypto_increment_nontransmitted_iv==SA_INCREMENT_NONTRANSMITTED_IV_TRUE)
+    {
+        status = crypto_handle_incrementing_nontransmitted_counter(tc_sdls_processed_frame->tc_sec_header.iv,sa_ptr->iv,sa_ptr->iv_len,sa_ptr->shivf_len,sa_ptr->arsnw);
+        if (status != CRYPTO_LIB_SUCCESS)
+        {
+            return status;
+        }
+    }
+    else // Not checking IV ARSNW or only non-transmitted portion is static; Note, non-transmitted IV in SA must match frame or will fail MAC check.
+    {
+        // Retrieve non-transmitted portion of IV from SA (if applicable)
+        memcpy(tc_sdls_processed_frame->tc_sec_header.iv, sa_ptr->iv, sa_ptr->iv_len-sa_ptr->shivf_len);
+    }
+
 #ifdef DEBUG
     printf("Full IV Value from Frame and SADB (if applicable):\n");
     Crypto_hexprint(tc_sdls_processed_frame->tc_sec_header.iv,sa_ptr->iv_len);
 #endif
 
-    // Parse non-transmitted portion of ARSN from SA
-    memcpy(tc_sdls_processed_frame->tc_sec_header.sn, sa_ptr->arsn, sa_ptr->arsn_len-sa_ptr->shsnf_len);
     // Parse transmitted portion of ARSN
     memcpy((tc_sdls_processed_frame->tc_sec_header.sn + (sa_ptr->arsn_len-sa_ptr->shsnf_len)),
            &(ingest[TC_FRAME_HEADER_SIZE + segment_hdr_len + SPI_LEN + sa_ptr->shivf_len]), sa_ptr->shsnf_len);
+
+    // Handle non-transmitted SN increment case (transmitted-portion roll-over)
+    if(sa_ptr->shsnf_len < sa_ptr->arsn_len &&
+       crypto_config->ignore_anti_replay==TC_IGNORE_ANTI_REPLAY_FALSE)
+    {
+        status = crypto_handle_incrementing_nontransmitted_counter(tc_sdls_processed_frame->tc_sec_header.sn,sa_ptr->arsn,sa_ptr->arsn_len,sa_ptr->shsnf_len,sa_ptr->arsnw);
+        if (status != CRYPTO_LIB_SUCCESS)
+        {
+            return status;
+        }
+    }
+    else // Not checking ARSN in ARSNW
+    {
+        // Parse non-transmitted portion of ARSN from SA
+        memcpy(tc_sdls_processed_frame->tc_sec_header.sn, sa_ptr->arsn, sa_ptr->arsn_len-sa_ptr->shsnf_len);
+
+    }
+
 #ifdef DEBUG
     printf("Full ARSN Value from Frame and SADB (if applicable):\n");
     Crypto_hexprint(tc_sdls_processed_frame->tc_sec_header.sn,sa_ptr->arsn_len);
@@ -939,6 +972,18 @@ int32_t Crypto_TC_ProcessSecurity(uint8_t* ingest, int *len_ingest, TC_t* tc_sdl
     if (crypto_config->ignore_anti_replay == TC_IGNORE_ANTI_REPLAY_FALSE && status == CRYPTO_LIB_SUCCESS)
     {
         status = Crypto_Check_Anti_Replay(sa_ptr, tc_sdls_processed_frame->tc_sec_header.sn, tc_sdls_processed_frame->tc_sec_header.iv);
+
+        if(status != CRYPTO_LIB_SUCCESS)
+        {
+            return status;
+        }
+
+        // Only save the SA (IV/ARSN) if checking the anti-replay counter; Otherwise we don't update.
+        status = sadb_routine->sadb_save_sa(sa_ptr);
+        if(status != CRYPTO_LIB_SUCCESS)
+        {
+            return status;
+        }
     }
 
     // Extended PDU processing, if applicable
@@ -1058,4 +1103,53 @@ static int32_t crypto_tc_validate_sa(SecurityAssociation_t *sa)
     }
 
     return CRYPTO_LIB_SUCCESS;
+}
+
+static int32_t crypto_handle_incrementing_nontransmitted_counter(uint8_t* dest, uint8_t* src, int src_full_len,int transmitted_len, int window)
+{
+    int32_t status = CRYPTO_LIB_SUCCESS;
+    // Copy IV to temp
+    uint8_t* temp_counter = malloc(src_full_len);
+    memcpy(temp_counter,src,src_full_len);
+
+    // Increment temp_counter Until Transmitted Portion Matches Frame.
+    uint8_t counter_matches = CRYPTO_TRUE;
+    for(int i = 0; i < window; i++)
+    {
+        Crypto_increment(temp_counter,src_full_len);
+        for(int x = (src_full_len - transmitted_len); x < src_full_len; x++)
+        {
+            //This increment doesn't match the frame!
+            if(temp_counter[x] != dest[x])
+            {
+                counter_matches = CRYPTO_FALSE;
+                break;
+            }
+        }
+        if(counter_matches == CRYPTO_TRUE)
+        {
+            break;
+        }
+        else if (i < window - 1) // Only reset flag if there are more  windows to check.
+        {
+            counter_matches = CRYPTO_TRUE; // reset the flag, and continue the for loop for the next
+            continue;
+        }
+
+    }
+
+    if(counter_matches == CRYPTO_TRUE)
+    {
+        // Retrieve non-transmitted portion of incremented counter that matches (and may have rolled over/incremented)
+        memcpy(dest, temp_counter, src_full_len - transmitted_len);
+#ifdef DEBUG
+        printf("Incremented IV is:\n");
+        Crypto_hexprint(temp_counter,src_full_len);
+#endif
+    }
+    else
+    {
+        status = CRYPTO_LIB_ERR_FRAME_COUNTER_DOESNT_MATCH_SA;
+    }
+    return status;
 }
\ No newline at end of file
diff --git a/src/src_main/sadb_routine_inmemory.template.c b/src/src_main/sadb_routine_inmemory.template.c
index 97e7f200..70b8d424 100644
--- a/src/src_main/sadb_routine_inmemory.template.c
+++ b/src/src_main/sadb_routine_inmemory.template.c
@@ -147,7 +147,7 @@ int32_t sadb_config(void)
     sa[4].abm = (uint8_t* )calloc(1, sa[4].abm_len * sizeof(uint8_t));
     sa[4].arsnw_len = 1;
     sa[4].arsnw = 5;
-    sa[4].arsn_len = (sa[4].arsnw * 2) + 1;
+    sa[4].arsn_len = 0;
     sa[4].gvcid_tc_blk.tfvn = 0;
     sa[4].gvcid_tc_blk.scid = SCID & 0x3FF;
     sa[4].gvcid_tc_blk.vcid = 0;
diff --git a/util/src_util/ut_tc_apply.c b/util/src_util/ut_tc_apply.c
index a00a1526..db88f215 100644
--- a/util/src_util/ut_tc_apply.c
+++ b/util/src_util/ut_tc_apply.c
@@ -302,6 +302,92 @@ UTEST(TC_APPLY_SECURITY, HAPPY_PATH_APPLY_STATIC_IV_ROLLOVER)
     free(ptr_enc_frame);
     ASSERT_EQ(CRYPTO_LIB_SUCCESS, return_val);
 }
+
+/**
+ * @brief Unit Test: Nominal Authorized Encryption With Partial ARSN Rollover, increment static ARSN
+ **/
+UTEST(TC_APPLY_SECURITY, HAPPY_PATH_APPLY_NONTRANSMITTED_INCREMENTING_ARSN_ROLLOVER)
+{
+    // Setup & Initialize CryptoLib
+    Crypto_Init_Unit_Test();
+    char* raw_tc_sdls_ping_h = "20030015000080d2c70008197f0b00310000b1fe3128";
+    char* raw_tc_sdls_ping_b = NULL;
+
+    char* new_arsn_h = "05FFFC";
+    char* new_arsn_b = NULL;
+
+    char* expected_arsn_h = "060001";
+    char* expected_arsn_b = NULL;
+
+    int raw_tc_sdls_ping_len = 0;
+    int new_arsn_len = 0;
+    int expected_arsn_len = 0;
+
+    SadbRoutine sadb_routine = get_sadb_routine_inmemory();
+
+    hex_conversion(raw_tc_sdls_ping_h, &raw_tc_sdls_ping_b, &raw_tc_sdls_ping_len);
+    hex_conversion(new_arsn_h, &new_arsn_b, &new_arsn_len);
+    hex_conversion(expected_arsn_h, &expected_arsn_b, &expected_arsn_len);
+    uint8_t* ptr_enc_frame = NULL;
+    uint16_t enc_frame_len = 0;
+
+    int32_t return_val = CRYPTO_LIB_ERROR;
+
+    SecurityAssociation_t* test_association = malloc(sizeof(SecurityAssociation_t) * sizeof(uint8_t));
+    // Expose the SADB Security Association for test edits.
+    sadb_routine->sadb_get_sa_from_spi(1, &test_association);
+    test_association->sa_state = SA_NONE;
+    sadb_routine->sadb_get_sa_from_spi(4, &test_association);
+    test_association->sa_state = SA_OPERATIONAL;
+    test_association->shivf_len = 0;
+    test_association->iv_len = 0;
+    test_association->est=0;
+    test_association->ast=1;
+    test_association->ecs_len=1;
+    test_association->ecs = calloc(1, test_association->ecs_len * sizeof(uint8_t));
+    *test_association->ecs = CRYPTO_CIPHER_NONE;
+    test_association->acs_len=1;
+    test_association->acs = calloc(1, test_association->acs_len * sizeof(uint8_t));
+    *test_association->acs = CRYPTO_MAC_CMAC_AES256;
+    test_association->arsn_len = 3;
+    test_association->shsnf_len = 2;
+    test_association->arsn = calloc(1,test_association->arsn_len);
+    memcpy(test_association->arsn, (uint8_t *)new_arsn_b, new_arsn_len);
+
+    return_val =
+            Crypto_TC_ApplySecurity((uint8_t* )raw_tc_sdls_ping_b, raw_tc_sdls_ping_len, &ptr_enc_frame, &enc_frame_len);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS,return_val);
+    return_val =
+            Crypto_TC_ApplySecurity((uint8_t* )raw_tc_sdls_ping_b, raw_tc_sdls_ping_len, &ptr_enc_frame, &enc_frame_len);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS,return_val);
+    return_val =
+            Crypto_TC_ApplySecurity((uint8_t* )raw_tc_sdls_ping_b, raw_tc_sdls_ping_len, &ptr_enc_frame, &enc_frame_len);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS,return_val);
+    return_val =
+            Crypto_TC_ApplySecurity((uint8_t* )raw_tc_sdls_ping_b, raw_tc_sdls_ping_len, &ptr_enc_frame, &enc_frame_len);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS,return_val);
+    return_val =
+            Crypto_TC_ApplySecurity((uint8_t* )raw_tc_sdls_ping_b, raw_tc_sdls_ping_len, &ptr_enc_frame, &enc_frame_len);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS,return_val);
+
+    printf("Expected ARSN:\n");
+    Crypto_hexprint(expected_arsn_b,expected_arsn_len);
+    printf("Actual SA ARSN:\n");
+    Crypto_hexprint(test_association->arsn,test_association->arsn_len);
+
+    for (int i = 0; i < test_association->arsn_len; i++)
+    {
+        printf("[%d] Truth: %02x, Actual: %02x\n", i, expected_arsn_b[i], *(test_association->arsn + i));
+        ASSERT_EQ(expected_arsn_b[i], *(test_association->arsn + i));
+    }
+
+    //Must shutdown after checking test_association ARSN since that will get freed!
+    Crypto_Shutdown();
+    free(raw_tc_sdls_ping_b);
+    free(ptr_enc_frame);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS, return_val);
+}
+
 /**
  * @brief Unit Test: Bad Spacecraft ID
  * This should pass the flawed hex string, and return CRYPTO_LIB_ERR_INVALID_SCID
diff --git a/util/src_util/ut_tc_process.c b/util/src_util/ut_tc_process.c
index 7333b17b..81d10ee2 100644
--- a/util/src_util/ut_tc_process.c
+++ b/util/src_util/ut_tc_process.c
@@ -399,20 +399,108 @@ UTEST(TC_PROCESS, HAPPY_PATH_PROCESS_NONTRANSMITTED_INCREMENTING_IV_ROLLOVER)
     ASSERT_EQ(test_association->iv[11],0xFF);
     // test_association->iv[5] = 0x01;
     return_val = Crypto_TC_ProcessSecurity(dec_test_00_b, &dec_test_00_len, tc_sdls_processed_frame);
-    //Tc_ProcessSecurity Rollover bug ( https://github.jpl.nasa.gov/ASEC/AMMOS-CryptoLib/issues/57 ), cannot assert this!
-//    ASSERT_EQ(CRYPTO_LIB_SUCCESS, return_val);
-//    ASSERT_EQ(test_association->iv[0] ,0x00);
-//    ASSERT_EQ(test_association->iv[1] ,0x00);
-//    ASSERT_EQ(test_association->iv[2] ,0x00);
-//    ASSERT_EQ(test_association->iv[3] ,0x00);
-//    ASSERT_EQ(test_association->iv[4] ,0x00);
-//    ASSERT_EQ(test_association->iv[5] ,0x01);
-//    ASSERT_EQ(test_association->iv[6] ,0x00);
-//    ASSERT_EQ(test_association->iv[7] ,0x00);
-//    ASSERT_EQ(test_association->iv[8] ,0x00);
-//    ASSERT_EQ(test_association->iv[9] ,0x00);
-//    ASSERT_EQ(test_association->iv[10],0x00);
-//    ASSERT_EQ(test_association->iv[11],0x00);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS, return_val);
+    ASSERT_EQ(test_association->iv[0] ,0x00);
+    ASSERT_EQ(test_association->iv[1] ,0x00);
+    ASSERT_EQ(test_association->iv[2] ,0x00);
+    ASSERT_EQ(test_association->iv[3] ,0x00);
+    ASSERT_EQ(test_association->iv[4] ,0x00);
+    ASSERT_EQ(test_association->iv[5] ,0x01);
+    ASSERT_EQ(test_association->iv[6] ,0x00);
+    ASSERT_EQ(test_association->iv[7] ,0x00);
+    ASSERT_EQ(test_association->iv[8] ,0x00);
+    ASSERT_EQ(test_association->iv[9] ,0x00);
+    ASSERT_EQ(test_association->iv[10],0x00);
+    ASSERT_EQ(test_association->iv[11],0x00);
+
+    Crypto_saPrint(test_association);
+
+    Crypto_Shutdown();
+
+    free(dec_test_fe_b);
+    free(dec_test_ff_b);
+    free(dec_test_00_b);
+    // free(test_association->ecs);
+    free(tc_sdls_processed_frame);
+    // sadb_routine->sadb_close();
+}
+
+UTEST(TC_PROCESS, HAPPY_PATH_PROCESS_NONTRANSMITTED_INCREMENTING_ARSN_ROLLOVER)
+{
+    // Setup & Initialize CryptoLib
+    Crypto_Init_Unit_Test();
+    Crypto_Config_CryptoLib(SADB_TYPE_INMEMORY, CRYPTOGRAPHY_TYPE_LIBGCRYPT, CRYPTO_TC_CREATE_FECF_TRUE, TC_PROCESS_SDLS_PDUS_TRUE, TC_HAS_PUS_HDR,
+                            TC_IGNORE_SA_STATE_FALSE, TC_IGNORE_ANTI_REPLAY_FALSE, TC_UNIQUE_SA_PER_MAP_ID_FALSE,
+                            TC_CHECK_FECF_TRUE, 0x3F, SA_INCREMENT_NONTRANSMITTED_IV_TRUE);
+
+    SadbRoutine sadb_routine = get_sadb_routine_inmemory();
+
+    char* dec_test_fe_h =
+            "2003002900000004FFFE80D2C70008197F0B00310000B1FE1C9119D059698FFE5AAE811572FA678D0741";
+    char* dec_test_ff_h =
+            "2003002900000004FFFF80D2C70008197F0B00310000B1FE1C9119D059698FFE5AAE811572FA678D8968";
+    char* dec_test_00_h =
+            "2003002900000004000080D2C70008197F0B00310000B1FE1C9119D059698FFE5AAE811572FA678D7824";
+
+    uint8_t *dec_test_fe_b, *dec_test_ff_b, *dec_test_00_b = NULL;
+    int dec_test_fe_len, dec_test_ff_len, dec_test_00_len = 0;
+
+    hex_conversion(dec_test_fe_h, (char**) &dec_test_fe_b, &dec_test_fe_len);
+    hex_conversion(dec_test_ff_h, (char**) &dec_test_ff_b, &dec_test_ff_len);
+    hex_conversion(dec_test_00_h, (char**) &dec_test_00_b, &dec_test_00_len);
+
+    SecurityAssociation_t* test_association = NULL;
+    test_association = malloc(sizeof(SecurityAssociation_t) * sizeof(uint8_t));
+
+    int32_t return_val = -1;
+
+    TC_t* tc_sdls_processed_frame;
+    tc_sdls_processed_frame = malloc(sizeof(uint8_t) * TC_SIZE);
+    memset(tc_sdls_processed_frame, 0, (sizeof(uint8_t) * TC_SIZE));
+
+    // Default SA
+    // Expose SA 1 for testing
+    sadb_routine->sadb_get_sa_from_spi(1, &test_association);
+    test_association->ecs = calloc(1, test_association->ecs_len * sizeof(uint8_t));
+    *test_association->ecs = CRYPTO_CIPHER_NONE;
+
+    // Deactive SA 1
+    test_association->sa_state = SA_NONE;
+
+    // Expose SA 4 for testing
+    sadb_routine->sadb_get_sa_from_spi(4, &test_association);
+    test_association->sa_state = SA_OPERATIONAL;
+    test_association->shivf_len = 0;
+    test_association->iv_len = 0;
+    test_association->est=0;
+    test_association->ast=1;
+    test_association->ecs_len=1;
+    test_association->ecs = calloc(1, test_association->ecs_len * sizeof(uint8_t));
+    *test_association->ecs = CRYPTO_CIPHER_NONE;
+    test_association->acs_len=1;
+    test_association->acs = calloc(1, test_association->acs_len * sizeof(uint8_t));
+    *test_association->acs = CRYPTO_MAC_CMAC_AES256;
+    test_association->arsn_len = 3;
+    test_association->shsnf_len = 2;
+    test_association->arsn = calloc(1,test_association->arsn_len);
+    // ARSN = "05FFFD"
+    test_association->arsn[0] = 0x05;
+    test_association->arsn[1] = 0xFF;
+    test_association->arsn[2] = 0xFD;
+
+    Crypto_saPrint(test_association);
+    return_val = Crypto_TC_ProcessSecurity(dec_test_fe_b, &dec_test_fe_len, tc_sdls_processed_frame);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS, return_val);
+    ASSERT_EQ(test_association->arsn[2],0xFE);
+    return_val = Crypto_TC_ProcessSecurity(dec_test_ff_b, &dec_test_ff_len, tc_sdls_processed_frame);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS, return_val);
+    ASSERT_EQ(test_association->arsn[2],0xFF);
+    // test_association->iv[5] = 0x01;
+    return_val = Crypto_TC_ProcessSecurity(dec_test_00_b, &dec_test_00_len, tc_sdls_processed_frame);
+    ASSERT_EQ(CRYPTO_LIB_SUCCESS, return_val);
+    ASSERT_EQ(test_association->arsn[0] ,0x06);
+    ASSERT_EQ(test_association->arsn[1] ,0x00);
+    ASSERT_EQ(test_association->arsn[2] ,0x00);
 
     Crypto_saPrint(test_association);