diff --git a/.gitignore b/.gitignore
index 12bde55..7c0c9eb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -60,3 +60,9 @@ target
 .idea/
 /specs/cells
 .vscode/
+webauthn_coverage
+webauthn_fuzzer
+tests/pw_webauthn_lib/corpus
+tests/pw_webauthn_lib/crash-*
+tests/pw_webauthn_lib/fuzz-*
+tests/pw_webauthn_lib/coverage/*
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..552e576
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.12)
+project(pw-lock C)
+set(CMAKE_C_STANDARD 11)
+# uncomment it for sanitize
+#set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fsanitize=undefined")
+add_compile_options(-Wno-macro-redefined)
+
+include_directories(deps/libecc/src)
+# deps/ckb-c-std-lib
+include_directories(c)
+include_directories(tests/pw_webauthn_lib)
+add_definitions(-DWORDSIZE=64)
+add_definitions(-DWITH_STDLIB)
+add_definitions(-D__unix__)
+add_definitions(-DCKB_SIMULATOR)
+add_definitions(-DNN_CONSISTENCY_CHECK)
+
+add_executable(pw_webauthn_lib tests/pw_webauthn_lib/main_test.c)
+
diff --git a/tests/pw_webauthn_lib/Makefile b/tests/pw_webauthn_lib/Makefile
new file mode 100644
index 0000000..724e953
--- /dev/null
+++ b/tests/pw_webauthn_lib/Makefile
@@ -0,0 +1,63 @@
+OS = Unknown
+ifneq ($(shell uname -a | grep -i Darwin),)
+	OS = MacOS
+endif
+ifneq ($(shell uname -a | grep -i Linux),)
+	OS = Linux
+endif
+ifeq ($(OS),Unknown)
+	echo "error: unsupported OS"; exit 1
+endif
+
+NPROC?=4
+CC=clang
+LLVM_PROFDATA=llvm-profdata
+LLVM_COV=llvm-cov
+
+CORPUS_DIR=corpus
+FLAGS=-I../../deps/libecc/src -I../../c -I. -DWORDSIZE=64 -DWITH_STDLIB -D__unix__ -DCKB_SIMULATOR -DNN_CONSISTENCY_CHECK -Wno-macro-redefined
+
+FUZZER_FLAGS=-g -O1 -fsanitize=fuzzer,address,undefined $(FLAGS)
+
+COVERAGE_DIR=coverage
+COVERAGE_FLAGS=-fprofile-instr-generate -fcoverage-mapping $(FLAGS)
+
+ifeq ($(OS),MacOS)
+	COVERAGE_FLAGS+=-Wl,-U,_LLVMFuzzerCustomMutator -Wl,-U,_LLVMFuzzerInitialize
+endif
+
+EXTERNAL_HEADERS=../../c/webauthn/pw_webauthn.h
+
+all: fuzzer coverage
+
+show: $(COVERAGE_DIR)/fuzzer.profdata
+	$(LLVM_COV) show --instr-profile=$(COVERAGE_DIR)/fuzzer.profdata webauthn_coverage
+
+report: $(COVERAGE_DIR)/fuzzer.profdata coverage $(EXTERNAL_HEADERS)
+	$(LLVM_COV) report --show-functions --instr-profile=$(COVERAGE_DIR)/fuzzer.profdata webauthn_coverage $(EXTERNAL_HEADERS)
+
+fuzzer:
+	clang $(FUZZER_FLAGS) fuzzer.c -o webauthn_fuzzer
+	
+coverage: $(EXTERNAL_HEADERS)
+	clang $(COVERAGE_FLAGS) coverage.c fuzzer.c -o webauthn_coverage
+
+start-fuzzer: fuzzer
+	./webauthn_fuzzer -workers=$(NPROC) -jobs=$(NPROC) -max_len=700 corpus
+
+clean:
+	rm -rf webauthn_fuzzer webauthn_coverage webauthn_fuzzer.dSYM
+
+#%.h:export
+#	ln -s $(CURDIR)/../$@ $(CURDIR)/$@
+
+%.profraw: coverage
+	echo "start webauthn_coverage"
+	LLVM_PROFILE_FILE=$@ ./webauthn_coverage $(CORPUS_DIR)/*
+
+%.profdata: %.profraw
+	$(LLVM_PROFDATA) merge --sparse $< -o $@
+
+.PHONY: all fuzzer coverage report
+
+.PRECIOUS: $(COVERAGE_DIR)/fuzzer.profraw $(COVERAGE_DIR)/fuzzer.profdata
diff --git a/tests/pw_webauthn_lib/README.md b/tests/pw_webauthn_lib/README.md
new file mode 100644
index 0000000..e2221c5
--- /dev/null
+++ b/tests/pw_webauthn_lib/README.md
@@ -0,0 +1,11 @@
+### Fuzzing test
+```bash
+make
+make start-fuzzer
+```
+
+Get code coverage by:
+```bash
+make report
+make show
+```
diff --git a/tests/pw_webauthn_lib/ckb_syscalls.h b/tests/pw_webauthn_lib/ckb_syscalls.h
new file mode 100644
index 0000000..3a85fad
--- /dev/null
+++ b/tests/pw_webauthn_lib/ckb_syscalls.h
@@ -0,0 +1,194 @@
+#ifndef CKB_C_STDLIB_CKB_SYSCALLS_H_
+#define CKB_C_STDLIB_CKB_SYSCALLS_H_
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+
+#define SYS_exit 93
+#define SYS_ckb_load_transaction 2051
+#define SYS_ckb_load_script 2052
+#define SYS_ckb_load_tx_hash 2061
+#define SYS_ckb_load_script_hash 2062
+#define SYS_ckb_load_cell 2071
+#define SYS_ckb_load_header 2072
+#define SYS_ckb_load_input 2073
+#define SYS_ckb_load_witness 2074
+#define SYS_ckb_load_cell_by_field 2081
+#define SYS_ckb_load_header_by_field 2082
+#define SYS_ckb_load_input_by_field 2083
+#define SYS_ckb_load_cell_data_as_code 2091
+#define SYS_ckb_load_cell_data 2092
+#define SYS_ckb_debug 2177
+
+#define CKB_SUCCESS 0
+#define CKB_INDEX_OUT_OF_BOUND 1
+#define CKB_ITEM_MISSING 2
+#define CKB_LENGTH_NOT_ENOUGH 3
+
+#define CKB_SOURCE_INPUT 1
+#define CKB_SOURCE_OUTPUT 2
+#define CKB_SOURCE_CELL_DEP 3
+#define CKB_SOURCE_HEADER_DEP 4
+#define CKB_SOURCE_GROUP_INPUT 0x0100000000000001
+#define CKB_SOURCE_GROUP_OUTPUT 0x0100000000000002
+
+#define CKB_CELL_FIELD_CAPACITY 0
+#define CKB_CELL_FIELD_DATA_HASH 1
+#define CKB_CELL_FIELD_LOCK 2
+#define CKB_CELL_FIELD_LOCK_HASH 3
+#define CKB_CELL_FIELD_TYPE 4
+#define CKB_CELL_FIELD_TYPE_HASH 5
+#define CKB_CELL_FIELD_OCCUPIED_CAPACITY 6
+
+#define CKB_HEADER_FIELD_EPOCH_NUMBER 0
+#define CKB_HEADER_FIELD_EPOCH_START_BLOCK_NUMBER 1
+#define CKB_HEADER_FIELD_EPOCH_LENGTH 2
+
+#define CKB_INPUT_FIELD_OUT_POINT 0
+#define CKB_INPUT_FIELD_SINCE 1
+
+int ckb_exit(int8_t code) { return 0;}
+
+int ckb_load_tx_hash(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_checked_load_tx_hash(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_load_script_hash(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_checked_load_script_hash(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_load_cell(void* addr, uint64_t* len, size_t offset, size_t index,
+                  size_t source) {
+  return 0;
+}
+
+int ckb_checked_load_cell(void* addr, uint64_t* len, size_t offset,
+                          size_t index, size_t source) {
+  return 0;
+}
+
+int ckb_load_input(void* addr, uint64_t* len, size_t offset, size_t index,
+                   size_t source) {
+  return 0;
+}
+
+int ckb_checked_load_input(void* addr, uint64_t* len, size_t offset,
+                           size_t index, size_t source) {
+  return 0;
+}
+
+int ckb_load_header(void* addr, uint64_t* len, size_t offset, size_t index,
+                    size_t source) {
+  return 0;
+}
+
+int ckb_checked_load_header(void* addr, uint64_t* len, size_t offset,
+                            size_t index, size_t source) {
+  return 0;
+}
+
+int ckb_load_witness(void* addr, uint64_t* len, size_t offset, size_t index,
+                     size_t source) {
+  return 0;
+}
+
+int ckb_checked_load_witness(void* addr, uint64_t* len, size_t offset,
+                             size_t index, size_t source) {
+  return 0;
+}
+
+int ckb_load_script(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_checked_load_script(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_load_transaction(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_checked_load_transaction(void* addr, uint64_t* len, size_t offset) {
+  return 0;
+}
+
+int ckb_load_cell_by_field(void* addr, uint64_t* len, size_t offset,
+                           size_t index, size_t source, size_t field) {
+  return 0;
+}
+
+int ckb_checked_load_cell_by_field(void* addr, uint64_t* len, size_t offset,
+                                   size_t index, size_t source, size_t field) {
+  return 0;
+}
+
+int ckb_load_header_by_field(void* addr, uint64_t* len, size_t offset,
+                             size_t index, size_t source, size_t field) {
+  return 0;
+}
+
+int ckb_checked_load_header_by_field(void* addr, uint64_t* len, size_t offset,
+                                     size_t index, size_t source,
+                                     size_t field) {
+  return 0;
+}
+
+int ckb_load_input_by_field(void* addr, uint64_t* len, size_t offset,
+                            size_t index, size_t source, size_t field) {
+  return 0;
+}
+
+int ckb_checked_load_input_by_field(void* addr, uint64_t* len, size_t offset,
+                                    size_t index, size_t source, size_t field) {
+  return 0;
+}
+
+int ckb_load_cell_code(void* addr, size_t memory_size, size_t content_offset,
+                       size_t content_size, size_t index, size_t source) {
+  return 0;
+}
+
+int ckb_load_cell_data(void* addr, uint64_t* len, size_t offset, size_t index,
+                       size_t source) {
+  return 0;
+}
+
+int ckb_checked_load_cell_data(void* addr, uint64_t* len, size_t offset,
+                               size_t index, size_t source) {
+  return 0;
+}
+
+int ckb_debug(const char* s) {
+  return 0;
+}
+
+int ckb_load_actual_type_witness(uint8_t* buf, uint64_t* len, size_t index,
+                                 size_t* type_source) {
+  return 0;
+}
+
+/* calculate inputs length */
+int ckb_calculate_inputs_len() {
+  return 0;
+}
+
+/*
+ * Look for dep cell with specific data hash, data_hash should a buffer with
+ * 32 bytes.
+ */
+int ckb_look_for_dep_with_hash(const uint8_t* data_hash, size_t* index) {
+  return 0;
+}
+
+#endif /* CKB_C_STDLIB_CKB_SYSCALLS_H_ */
diff --git a/tests/pw_webauthn_lib/coverage.c b/tests/pw_webauthn_lib/coverage.c
new file mode 100644
index 0000000..1b44764
--- /dev/null
+++ b/tests/pw_webauthn_lib/coverage.c
@@ -0,0 +1,41 @@
+/*===- StandaloneFuzzTargetMain.c - standalone main() for fuzz targets. ---===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// This main() function can be linked to a fuzz target (i.e. a library
+// that exports LLVMFuzzerTestOneInput() and possibly LLVMFuzzerInitialize())
+// instead of libFuzzer. This main() function will not perform any fuzzing
+// but will simply feed all input files one by one to the fuzz target.
+//
+// Use this file to provide reproducers for bugs when linking against libFuzzer
+// or other fuzzing engine is undesirable.
+//===----------------------------------------------------------------------===*/
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+extern int LLVMFuzzerTestOneInput(const unsigned char *data, size_t size);
+__attribute__((weak)) extern int LLVMFuzzerInitialize(int *argc, char ***argv);
+
+int main(int argc, char **argv) {
+  fprintf(stderr, "StandaloneFuzzTargetMain: running %d inputs\n", argc - 1);
+  if (LLVMFuzzerInitialize) LLVMFuzzerInitialize(&argc, &argv);
+  for (int i = 1; i < argc; i++) {
+    fprintf(stderr, "Running: %s\n", argv[i]);
+    FILE *f = fopen(argv[i], "r");
+    assert(f);
+    fseek(f, 0, SEEK_END);
+    size_t len = ftell(f);
+    fseek(f, 0, SEEK_SET);
+    unsigned char *buf = (unsigned char *)malloc(len);
+    size_t n_read = fread(buf, 1, len, f);
+    fclose(f);
+    assert(n_read == len);
+    LLVMFuzzerTestOneInput(buf, len);
+    free(buf);
+    fprintf(stderr, "Done:    %s: (%zd bytes)\n", argv[i], n_read);
+  }
+}
diff --git a/tests/pw_webauthn_lib/fuzzer.c b/tests/pw_webauthn_lib/fuzzer.c
new file mode 100644
index 0000000..344c354
--- /dev/null
+++ b/tests/pw_webauthn_lib/fuzzer.c
@@ -0,0 +1,23 @@
+#include "ckb_syscalls.h"
+#include "webauthn/pw_webauthn_lib.c"
+#include "stubs.h"
+
+
+/**
+ * @param message: transaction message digest, size is 32 bytes
+ * @param lock_args: last 20 bytes sha256 hash of pubkey, used to shield
+ * the real pubkey. size is 20 bytes
+ * @param lock_bytes: transaction signature in witness.lock, size is 500 bytes
+ *
+ */
+int validate_webauthn(unsigned char* message, unsigned char* lock_args,
+                      unsigned char* lock_bytes, uint64_t lock_bytes_size);
+
+
+int LLVMFuzzerTestOneInput(uint8_t *data, size_t size) {
+  if (size < (564+20+32)) {
+    return 0;
+  }
+  validate_webauthn(data, data+32, data+32+20, 564);
+  return 0;
+}
diff --git a/tests/pw_webauthn_lib/main_test.c b/tests/pw_webauthn_lib/main_test.c
new file mode 100644
index 0000000..ba16023
--- /dev/null
+++ b/tests/pw_webauthn_lib/main_test.c
@@ -0,0 +1,13 @@
+
+#include "ckb_syscalls.h"
+#include "webauthn/pw_webauthn_lib.c"
+#include "stubs.h"
+
+
+int verify_challenge_in_client_data(const u8* digest_message,
+                                    const u8* client_data,
+                                    int client_data_len);
+int main() {
+
+}
+
diff --git a/tests/pw_webauthn_lib/stubs.h b/tests/pw_webauthn_lib/stubs.h
new file mode 100644
index 0000000..8e1a6ef
--- /dev/null
+++ b/tests/pw_webauthn_lib/stubs.h
@@ -0,0 +1,55 @@
+#ifndef PW_LOCK_TESTS_SECP256R1_SHA256_SIGHASH_STUBS_H_
+#define PW_LOCK_TESTS_SECP256R1_SHA256_SIGHASH_STUBS_H_
+
+int aff_pt_import_from_buf(aff_pt_t pt,
+                           const u8 *pt_buf,
+                           u16 pt_buf_len, ec_shortw_crv_src_t crv) {
+  return 0;
+}
+
+
+const ec_str_params *ec_get_curve_params_by_name(const u8 *ec_name,
+                                                 u8 ec_name_len) {
+  return NULL;
+}
+
+void ec_shortw_aff_to_prj(prj_pt_t out, aff_pt_src_t in) {
+
+}
+
+int ec_verify_finalize(struct ec_verify_context *ctx) {
+  return 0;
+}
+
+int ec_verify_init(struct ec_verify_context *ctx, const ec_pub_key *pub_key,
+                   const u8 *sig, u8 siglen,
+                   ec_sig_alg_type sig_type, hash_alg_type hash_type)
+{
+  return 0;
+}
+int ec_verify_update(struct ec_verify_context *ctx,
+                     const u8 *chunk, u32 chunklen)
+{
+  return 0;
+
+}
+
+void import_params(ec_params *out_params, const ec_str_params *in_str_params)
+{
+
+}
+
+void sha256(const u8 *input, u32 ilen, u8 output[SHA256_DIGEST_SIZE]) {
+}
+void sha256_final(sha256_context *ctx, u8 output[SHA256_DIGEST_SIZE]) {
+}
+void sha256_init(sha256_context *ctx)
+{
+
+}
+
+void sha256_update(sha256_context *ctx, const u8 *input, u32 ilen)
+{
+
+}
+#endif //PW_LOCK_TESTS_SECP256R1_SHA256_SIGHASH_STUBS_H_