From 12f6ee3806c1f04a682b4c31aeb510a2dca602ef Mon Sep 17 00:00:00 2001
From: Huaxin Lu <luhuaxin1@huawei.com>
Date: Fri, 1 Sep 2023 20:27:45 +0800
Subject: [PATCH] use default id if SM2 id is not set

Signed-off-by: Huaxin Lu <luhuaxin1@huawei.com>
---
 crypto/sm2/sm2_sign.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/crypto/sm2/sm2_sign.c b/crypto/sm2/sm2_sign.c
index ff5be9b..33d3a73 100644
--- a/crypto/sm2/sm2_sign.c
+++ b/crypto/sm2/sm2_sign.c
@@ -42,6 +42,8 @@ int ossl_sm2_compute_z_digest(uint8_t *out,
     uint8_t *buf = NULL;
     uint16_t entl = 0;
     uint8_t e_byte = 0;
+    const uint8_t *f_id = id;
+    size_t f_id_len = id_len;
 
     hash = EVP_MD_CTX_new();
     ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(key));
@@ -68,15 +70,21 @@ int ossl_sm2_compute_z_digest(uint8_t *out,
         goto done;
     }
 
+    /* if id is not set, use default id */
+    if (f_id == NULL || f_id_len == 0) {
+        f_id = (const uint8_t *)SM2_DEFAULT_USERID;
+        f_id_len = strlen(SM2_DEFAULT_USERID);
+    }
+
     /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */
 
-    if (id_len >= (UINT16_MAX / 8)) {
+    if (f_id_len >= (UINT16_MAX / 8)) {
         /* too large */
         ERR_raise(ERR_LIB_SM2, SM2_R_ID_TOO_LARGE);
         goto done;
     }
 
-    entl = (uint16_t)(8 * id_len);
+    entl = (uint16_t)(8 * f_id_len);
 
     e_byte = entl >> 8;
     if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
@@ -89,7 +97,7 @@ int ossl_sm2_compute_z_digest(uint8_t *out,
         goto done;
     }
 
-    if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) {
+    if (f_id_len > 0 && !EVP_DigestUpdate(hash, f_id, f_id_len)) {
         ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
         goto done;
     }
-- 
2.33.0