C._goboringcrypto_HMAC_CTX_init(&h.ctx2)
	if C._goboringcrypto_HMAC_CTX_copy_ex(&h.ctx2, &h.ctx) == 0 {
		panic("boringcrypto: HMAC_CTX_copy_ex failed")
	}
	C._goboringcrypto_HMAC_Final(&h.ctx2, (*C.uint8_t)(unsafe.Pointer(&h.sum[0])), nil)
	C._goboringcrypto_HMAC_CTX_cleanup(&h.ctx2)
	return append(in, h.sum...)

void _goboringcrypto_HMAC_CTX_cleanup(GO_HMAC_CTX*);
int _goboringcrypto_HMAC_Init(GO_HMAC_CTX*, const void*, int, const GO_EVP_MD*);
int _goboringcrypto_HMAC_Update(GO_HMAC_CTX*, const uint8_t*, size_t);
int _goboringcrypto_HMAC_Final(GO_HMAC_CTX*, uint8_t*, unsigned int*);
size_t _goboringcrypto_HMAC_size(const GO_HMAC_CTX*);
int _goboringcrypto_HMAC_CTX_copy_ex(GO_HMAC_CTX *dest, const GO_HMAC_CTX *src);

// #include <openssl/aes.h>