diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index 65ab229..8936f0a 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -56,6 +56,17 @@
 /* Error codes in range 0x0023-0x0025 */
 #define MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE               -0x0023  /**< Feature not available. For example, an unsupported AES key size. */
 #define MBEDTLS_ERR_AES_HW_ACCEL_FAILED                   -0x0025  /**< AES hardware accelerator failed. */
+#define MBEDTLS_ERR_AES_BAD_INPUT_DATA                    -0x0027  /**< Invalid
+input data. */
+
+#if defined( MBEDTLS_CHECK_PARAMS )
+#define MBEDTLS_AES_VALIDATE( cond )  do{ if( !(cond)  ) \
+                                        return MBEDTLS_ERR_AES_BAD_INPUT_DATA; \
+                                      } while(0);
+#else
+/* No validation of parameters will be performed */
+#define MBEDTLS_AES_VALIDATE( cond)
+#endif
 
 #if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
     !defined(inline) && !defined(__cplusplus)
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 8baf439..29ceddc 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -221,6 +221,25 @@
  */
 //#define MBEDTLS_DEPRECATED_REMOVED
 
+/**
+ * \def MBEDTLS_PARAM_VALIDATION_LEVEL
+ *
+ * The defined parameter validation level for the library. This configuration
+ * controls whether the library validates parameters passed to it.
+ *
+ * Application code that deals with 3rd party input may wish to enable such
+ * validation, whilst code on closed systems, such as embedded systems, where
+ * the input is controlled and predictable, may wish to disable it entirely to
+ * reduce the code size of the library.
+ *
+ * When the symbol is not defined, no parameter validation except that required
+ * to ensure the integrity or security of the library are performed.
+ *
+ * When the symbol is defined, all parameters will be validated, and an error
+ * code returned where appropriate.
+ */
+#define MBEDTLS_CHECK_PARAMS
+
 /* \} name SECTION: System support */
 
 /**
diff --git a/library/aes.c b/library/aes.c
index 59c5165..66af3e1 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -545,14 +545,7 @@
     unsigned int i;
     uint32_t *RK;
 
-#if !defined(MBEDTLS_AES_ROM_TABLES)
-    if( aes_init_done == 0 )
-    {
-        aes_gen_tables();
-        aes_init_done = 1;
-
-    }
-#endif
+    MBEDTLS_AES_VALIDATE( ctx != NULL && key != NULL );
 
     switch( keybits )
     {
@@ -562,6 +555,15 @@
         default : return( MBEDTLS_ERR_AES_INVALID_KEY_LENGTH );
     }
 
+#if !defined(MBEDTLS_AES_ROM_TABLES)
+    if( aes_init_done == 0 )
+    {
+        aes_gen_tables();
+        aes_init_done = 1;
+
+    }
+#endif
+
 #if defined(MBEDTLS_PADLOCK_C) && defined(MBEDTLS_PADLOCK_ALIGN16)
     if( aes_padlock_ace == -1 )
         aes_padlock_ace = mbedtls_padlock_has_support( MBEDTLS_PADLOCK_ACE );
diff --git a/scripts/abi_check.py b/scripts/abi_check.py
new file mode 100755
index 0000000..8f9cd0f
--- /dev/null
+++ b/scripts/abi_check.py
@@ -0,0 +1,241 @@
+#!/usr/bin/env python3
+"""
+This file is part of Mbed TLS (https://tls.mbed.org)
+
+Copyright (c) 2018, Arm Limited, All Rights Reserved
+
+Purpose
+
+This script is a small wrapper around the abi-compliance-checker and
+abi-dumper tools, applying them to compare the ABI and API of the library
+files from two different Git revisions within an Mbed TLS repository.
+The results of the comparison are formatted as HTML and stored at
+a configurable location. Returns 0 on success, 1 on ABI/API non-compliance,
+and 2 if there is an error while running the script.
+Note: must be run from Mbed TLS root.
+"""
+
+import os
+import sys
+import traceback
+import shutil
+import subprocess
+import argparse
+import logging
+import tempfile
+
+
+class AbiChecker(object):
+
+    def __init__(self, report_dir, old_rev, new_rev, keep_all_reports):
+        self.repo_path = "."
+        self.log = None
+        self.setup_logger()
+        self.report_dir = os.path.abspath(report_dir)
+        self.keep_all_reports = keep_all_reports
+        self.should_keep_report_dir = os.path.isdir(self.report_dir)
+        self.old_rev = old_rev
+        self.new_rev = new_rev
+        self.mbedtls_modules = ["libmbedcrypto", "libmbedtls", "libmbedx509"]
+        self.old_dumps = {}
+        self.new_dumps = {}
+        self.git_command = "git"
+        self.make_command = "make"
+
+    def check_repo_path(self):
+        current_dir = os.path.realpath('.')
+        root_dir = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
+        if current_dir != root_dir:
+            raise Exception("Must be run from Mbed TLS root")
+
+    def setup_logger(self):
+        self.log = logging.getLogger()
+        self.log.setLevel(logging.INFO)
+        self.log.addHandler(logging.StreamHandler())
+
+    def check_abi_tools_are_installed(self):
+        for command in ["abi-dumper", "abi-compliance-checker"]:
+            if not shutil.which(command):
+                raise Exception("{} not installed, aborting".format(command))
+
+    def get_clean_worktree_for_git_revision(self, git_rev):
+        self.log.info(
+            "Checking out git worktree for revision {}".format(git_rev)
+        )
+        git_worktree_path = tempfile.mkdtemp()
+        worktree_process = subprocess.Popen(
+            [self.git_command, "worktree", "add", git_worktree_path, git_rev],
+            cwd=self.repo_path,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT
+        )
+        worktree_output, _ = worktree_process.communicate()
+        self.log.info(worktree_output.decode("utf-8"))
+        if worktree_process.returncode != 0:
+            raise Exception("Checking out worktree failed, aborting")
+        return git_worktree_path
+
+    def build_shared_libraries(self, git_worktree_path):
+        my_environment = os.environ.copy()
+        my_environment["CFLAGS"] = "-g -Og"
+        my_environment["SHARED"] = "1"
+        make_process = subprocess.Popen(
+            self.make_command,
+            env=my_environment,
+            cwd=git_worktree_path,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT
+        )
+        make_output, _ = make_process.communicate()
+        self.log.info(make_output.decode("utf-8"))
+        if make_process.returncode != 0:
+            raise Exception("make failed, aborting")
+
+    def get_abi_dumps_from_shared_libraries(self, git_ref, git_worktree_path):
+        abi_dumps = {}
+        for mbed_module in self.mbedtls_modules:
+            output_path = os.path.join(
+                self.report_dir, "{}-{}.dump".format(mbed_module, git_ref)
+            )
+            abi_dump_command = [
+                "abi-dumper",
+                os.path.join(
+                    git_worktree_path, "library", mbed_module + ".so"),
+                "-o", output_path,
+                "-lver", git_ref
+            ]
+            abi_dump_process = subprocess.Popen(
+                abi_dump_command,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.STDOUT
+            )
+            abi_dump_output, _ = abi_dump_process.communicate()
+            self.log.info(abi_dump_output.decode("utf-8"))
+            if abi_dump_process.returncode != 0:
+                raise Exception("abi-dumper failed, aborting")
+            abi_dumps[mbed_module] = output_path
+        return abi_dumps
+
+    def cleanup_worktree(self, git_worktree_path):
+        shutil.rmtree(git_worktree_path)
+        worktree_process = subprocess.Popen(
+            [self.git_command, "worktree", "prune"],
+            cwd=self.repo_path,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT
+        )
+        worktree_output, _ = worktree_process.communicate()
+        self.log.info(worktree_output.decode("utf-8"))
+        if worktree_process.returncode != 0:
+            raise Exception("Worktree cleanup failed, aborting")
+
+    def get_abi_dump_for_ref(self, git_rev):
+        git_worktree_path = self.get_clean_worktree_for_git_revision(git_rev)
+        self.build_shared_libraries(git_worktree_path)
+        abi_dumps = self.get_abi_dumps_from_shared_libraries(
+            git_rev, git_worktree_path
+        )
+        self.cleanup_worktree(git_worktree_path)
+        return abi_dumps
+
+    def get_abi_compatibility_report(self):
+        compatibility_report = ""
+        compliance_return_code = 0
+        for mbed_module in self.mbedtls_modules:
+            output_path = os.path.join(
+                self.report_dir, "{}-{}-{}.html".format(
+                    mbed_module, self.old_rev, self.new_rev
+                )
+            )
+            abi_compliance_command = [
+                "abi-compliance-checker",
+                "-l", mbed_module,
+                "-old", self.old_dumps[mbed_module],
+                "-new", self.new_dumps[mbed_module],
+                "-strict",
+                "-report-path", output_path
+            ]
+            abi_compliance_process = subprocess.Popen(
+                abi_compliance_command,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.STDOUT
+            )
+            abi_compliance_output, _ = abi_compliance_process.communicate()
+            self.log.info(abi_compliance_output.decode("utf-8"))
+            if abi_compliance_process.returncode == 0:
+                compatibility_report += (
+                    "No compatibility issues for {}\n".format(mbed_module)
+                )
+                if not self.keep_all_reports:
+                    os.remove(output_path)
+            elif abi_compliance_process.returncode == 1:
+                compliance_return_code = 1
+                self.should_keep_report_dir = True
+                compatibility_report += (
+                    "Compatibility issues found for {}, "
+                    "for details see {}\n".format(mbed_module, output_path)
+                )
+            else:
+                raise Exception(
+                    "abi-compliance-checker failed with a return code of {},"
+                    " aborting".format(abi_compliance_process.returncode)
+                )
+            os.remove(self.old_dumps[mbed_module])
+            os.remove(self.new_dumps[mbed_module])
+        if not self.should_keep_report_dir and not self.keep_all_reports:
+            os.rmdir(self.report_dir)
+        self.log.info(compatibility_report)
+        return compliance_return_code
+
+    def check_for_abi_changes(self):
+        self.check_repo_path()
+        self.check_abi_tools_are_installed()
+        self.old_dumps = self.get_abi_dump_for_ref(self.old_rev)
+        self.new_dumps = self.get_abi_dump_for_ref(self.new_rev)
+        return self.get_abi_compatibility_report()
+
+
+def run_main():
+    try:
+        parser = argparse.ArgumentParser(
+            description=(
+                """This script is a small wrapper around the
+                abi-compliance-checker and abi-dumper tools, applying them
+                to compare the ABI and API of the library files from two
+                different Git revisions within an Mbed TLS repository.
+                The results of the comparison are formatted as HTML and stored
+                at a configurable location. Returns 0 on success, 1 on ABI/API
+                non-compliance, and 2 if there is an error while running the
+                script. Note: must be run from Mbed TLS root."""
+            )
+        )
+        parser.add_argument(
+            "-r", "--report-dir", type=str, default="reports",
+            help="directory where reports are stored, default is reports",
+        )
+        parser.add_argument(
+            "-k", "--keep-all-reports", action="store_true",
+            help="keep all reports, even if there are no compatibility issues",
+        )
+        parser.add_argument(
+            "-o", "--old-rev", type=str, help="revision for old version",
+            required=True
+        )
+        parser.add_argument(
+            "-n", "--new-rev", type=str, help="revision for new version",
+            required=True
+        )
+        abi_args = parser.parse_args()
+        abi_check = AbiChecker(
+            abi_args.report_dir, abi_args.old_rev,
+            abi_args.new_rev, abi_args.keep_all_reports
+        )
+        return_code = abi_check.check_for_abi_changes()
+        sys.exit(return_code)
+    except Exception:
+        traceback.print_exc()
+        sys.exit(2)
+
+
+if __name__ == "__main__":
+    run_main()
diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index 9a98218..b134b03 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -445,6 +445,23 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE */
+void aes_invalid_param( )
+{
+    mbedtls_aes_context dummy_ctx;
+    const unsigned char key[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 };
+
+    /* mbedtls_aes_setkey_enc() */
+    TEST_ASSERT( mbedtls_aes_setkey_enc( NULL, key, 128  )
+                                            == MBEDTLS_ERR_AES_BAD_INPUT_DATA );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &dummy_ctx, NULL, 128  )
+                                            == MBEDTLS_ERR_AES_BAD_INPUT_DATA );
+
+exit:
+    return;
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
 void aes_selftest()
 {
diff --git a/tests/suites/test_suite_aes.rest.data b/tests/suites/test_suite_aes.rest.data
index bbb222f..3ec916d 100644
--- a/tests/suites/test_suite_aes.rest.data
+++ b/tests/suites/test_suite_aes.rest.data
@@ -10,6 +10,10 @@
 AES-256-CBC Decrypt (Invalid input length)
 aes_decrypt_cbc:"0000000000000000000000000000000000000000000000000000000000000000":"00000000000000000000000000000000":"623a52fcea5d443e48d9181ab32c74":"":MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
 
+AES - Invalid parameters
+depends_on:MBEDTLS_CHECK_PARAMS
+aes_invalid_param:
+
 AES Selftest
 depends_on:MBEDTLS_SELF_TEST
 aes_selftest: