diff --git a/c/openssl/_demo/chmacdemo/hmac.go b/c/openssl/_demo/chmacdemo/hmac.go
new file mode 100644
index 00000000..10fa585d
--- /dev/null
+++ b/c/openssl/_demo/chmacdemo/hmac.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"unsafe"
+
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/openssl"
+)
+
+func main() {
+	str := "Hello, World!"
+	key := "123456"
+	var lenKey = len(key)
+
+	var digest = make([]byte, openssl.EVP_MAX_MD_SIZE)
+	var digestLen c.Uint
+	ctx := openssl.NewHMAC_CTX()
+	if ctx == nil {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error creating HMAC_CTX"))
+		return
+	}
+	defer ctx.Free()
+
+	var ret c.Int = ctx.InitEx(unsafe.Pointer(unsafe.StringData(key)), c.Int(lenKey), openssl.EVP_sha256(), nil)
+	if ret == 0 {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error initializing HMAC_CTX"))
+		return
+	}
+	ret = ctx.UpdateString(str)
+	if ret == 0 {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error updating HMAC_CTX"))
+		return
+	}
+	ret = ctx.Final(unsafe.SliceData(digest), &digestLen)
+	if ret == 0 {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error finalizing HMAC_CTX"))
+		return
+	}
+	fmt.Print("HMAC: ")
+	for i := 0; i < int(digestLen); i++ {
+		fmt.Printf("%02x", digest[i])
+	}
+	fmt.Print("\n")
+}
diff --git a/c/openssl/hmac.go b/c/openssl/hmac.go
new file mode 100644
index 00000000..80b49143
--- /dev/null
+++ b/c/openssl/hmac.go
@@ -0,0 +1,121 @@
+package openssl
+
+import (
+	"unsafe"
+
+	"github.com/goplus/llgo/c"
+)
+
+const EVP_MAX_MD_SIZE = 64 /* longest known is SHA512 */
+
+// const EVP_MD *EVP_sha1(void)
+//
+//go:linkname EVP_sha1 C.EVP_sha1
+func EVP_sha1() *EVP_MD
+
+// const EVP_MD *EVP_sha224(void)
+//
+//go:linkname EVP_sha224 C.EVP_sha224
+func EVP_sha224() *EVP_MD
+
+// func EVP_sha256() *EVP_MD
+//
+//go:linkname EVP_sha256 C.EVP_sha256
+func EVP_sha256() *EVP_MD
+
+// const EVP_MD *EVP_sha512_224(void)
+//
+//go:linkname EVP_sha512_224 C.EVP_sha512_224
+func EVP_sha512_224() *EVP_MD
+
+// const EVP_MD *EVP_sha512_256(void)
+//
+//go:linkname EVP_sha512_256 C.EVP_sha512_256
+func EVP_sha512_256() *EVP_MD
+
+// const EVP_MD *EVP_sha384(void)
+//
+//go:linkname EVP_sha384 C.EVP_sha384
+func EVP_sha384() *EVP_MD
+
+// const EVP_MD *EVP_sha512(void)
+//
+//go:linkname EVP_sha512 C.EVP_sha512
+func EVP_sha512() *EVP_MD
+
+type EVP_MD struct {
+	Unused [0]byte
+}
+
+type EVP_MD_CTX struct {
+	Unused [0]byte
+}
+
+type HMAC_CTX struct {
+	Unused [0]byte
+}
+
+// OSSL_DEPRECATEDIN_3_0 HMAC_CTX *HMAC_CTX_new(void);
+//
+//go:linkname NewHMAC_CTX C.HMAC_CTX_new
+func NewHMAC_CTX() *HMAC_CTX
+
+// OSSL_DEPRECATEDIN_3_0 void HMAC_CTX_free(HMAC_CTX *ctx);
+//
+// llgo:link (*HMAC_CTX).Free C.HMAC_CTX_free
+func (c *HMAC_CTX) Free() {}
+
+// OSSL_DEPRECATEDIN_3_0 size_t HMAC_size(const HMAC_CTX *e);
+//
+// llgo:link (*HMAC_CTX).Size C.HMAC_size
+func (c *HMAC_CTX) Size() uintptr { return 0 }
+
+// OSSL_DEPRECATEDIN_3_0 int HMAC_CTX_reset(HMAC_CTX *ctx);
+//
+// llgo:link (*HMAC_CTX).Reset C.HMAC_CTX_reset
+func (c *HMAC_CTX) Reset() c.Int { return 0 }
+
+// OSSL_DEPRECATEDIN_1_1_0 __owur int HMAC_Init(HMAC_CTX *ctx,
+// const void *key, int len,
+// const EVP_MD *md);
+//
+// llgo:link (*HMAC_CTX).Init C.HMAC_Init
+func (c *HMAC_CTX) Init(key unsafe.Pointer, len c.Int, md *EVP_MD) c.Int { return 0 }
+
+// OSSL_DEPRECATEDIN_3_0 int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int len,
+// const EVP_MD *md, ENGINE *impl);
+//
+// llgo:link (*HMAC_CTX).InitEx C.HMAC_Init_ex
+func (c *HMAC_CTX) InitEx(key unsafe.Pointer, len c.Int, md *EVP_MD, impl unsafe.Pointer) c.Int {
+	return 0
+}
+
+// OSSL_DEPRECATEDIN_3_0 int HMAC_Update(HMAC_CTX *ctx, const unsigned char *data,
+// size_t len);
+//
+// llgo:link (*HMAC_CTX).Update C.HMAC_Update
+func (c *HMAC_CTX) Update(data unsafe.Pointer, len uintptr) c.Int { return 0 }
+
+func (c *HMAC_CTX) UpdateBytes(data []byte) c.Int {
+	return c.Update(unsafe.Pointer(unsafe.SliceData(data)), uintptr(len(data)))
+}
+
+func (c *HMAC_CTX) UpdateString(data string) c.Int {
+	return c.Update(unsafe.Pointer(unsafe.StringData(data)), uintptr(len(data)))
+}
+
+// OSSL_DEPRECATEDIN_3_0 int HMAC_Final(HMAC_CTX *ctx, unsigned char *md,
+// unsigned int *len);
+//
+// llgo:link (*HMAC_CTX).Final C.HMAC_Final
+func (c *HMAC_CTX) Final(md *byte, len *c.Uint) c.Int { return 0 }
+
+// OSSL_DEPRECATEDIN_3_0 __owur int HMAC_CTX_copy(HMAC_CTX *dctx, HMAC_CTX *sctx);
+//
+// llgo:link (*HMAC_CTX).Copy C.HMAC_CTX_copy
+func (c *HMAC_CTX) Copy(sctx *HMAC_CTX) c.Int { return 0 }
+
+// OSSL_DEPRECATEDIN_3_0 void HMAC_CTX_set_flags(HMAC_CTX *ctx, unsigned long flags);
+//
+// llgo:link (*HMAC_CTX).SetFlags C.HMAC_CTX_set_flags
+func (c *HMAC_CTX) SetFlags(flags c.Ulong) {}