--- a/libtomcrypt/src/pk/ecc/ecc_sign_hash.c	Thu Mar 21 23:28:59 2019 +0800
+++ b/libtomcrypt/src/pk/ecc/ecc_sign_hash.c	Fri Jun 26 21:07:34 2020 +0800
@@ -14,14 +14,14 @@
 /**
   @file ecc_sign_hash.c
   ECC Crypto, Tom St Denis
-*/  
+*/
 
 static int _ecc_sign_hash(const unsigned char *in,  unsigned long inlen,
-                        unsigned char *out, unsigned long *outlen, 
+                                unsigned char *out, unsigned long *outlen,
                                 prng_state *prng, int wprng, ecc_key *key, int sigformat)
 {
    ecc_key       pubkey;
-   void          *r, *s, *e, *p;
+   void          *r, *s, *e, *p, *b;
    int           err, max_iterations = LTC_PK_MAX_RETRIES;
    unsigned long pbits, pbytes, i, shift_right;
    unsigned char ch, buf[MAXBLOCKSIZE];
@@ -35,21 +35,21 @@
    if (key->type != PK_PRIVATE) {
       return CRYPT_PK_NOT_PRIVATE;
    }
-   
+
    /* is the IDX valid ?  */
    if (ltc_ecc_is_valid_idx(key->idx) != 1) {
       return CRYPT_PK_INVALID_TYPE;
    }
-   
+
    if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
       return err;
    }
 
    /* init the bignums */
-   if ((err = mp_init_multi(&r, &s, &p, &e, NULL)) != CRYPT_OK) { 
+   if ((err = mp_init_multi(&r, &s, &p, &e, &b, NULL)) != CRYPT_OK) {
       return err;
    }
-   if ((err = mp_read_radix(p, (char *)key->dp->order, 16)) != CRYPT_OK)                      { goto errnokey; }
+   if ((err = mp_read_radix(p, (char *)key->dp->order, 16)) != CRYPT_OK)              { goto errnokey; }
 
    /* get the hash and load it as a bignum into 'e' */
    pbits = mp_count_bits(p);
@@ -77,21 +77,24 @@
       }
 
       /* find r = x1 mod n */
-      if ((err = mp_mod(pubkey.pubkey.x, p, r)) != CRYPT_OK)                 { goto error; }
+      if ((err = mp_mod(pubkey.pubkey.x, p, r)) != CRYPT_OK)                          { goto error; }
 
       if (mp_iszero(r) == LTC_MP_YES) {
          ecc_free(&pubkey);
-      } else { 
-        /* find s = (e + xr)/k */
-        if ((err = mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK)            { goto error; } /* k = 1/k */
-        if ((err = mp_mulmod(key->k, r, p, s)) != CRYPT_OK)                  { goto error; } /* s = xr */
-        if ((err = mp_add(e, s, s)) != CRYPT_OK)                             { goto error; } /* s = e +  xr */
-        if ((err = mp_mod(s, p, s)) != CRYPT_OK)                             { goto error; } /* s = e +  xr */
-        if ((err = mp_mulmod(s, pubkey.k, p, s)) != CRYPT_OK)                { goto error; } /* s = (e + xr)/k */
-        ecc_free(&pubkey);
-        if (mp_iszero(s) == LTC_MP_NO) {
-           break;
-        }
+      } else {
+         if ((err = rand_bn_upto(b, p, prng, wprng)) != CRYPT_OK)          { goto error; } /* b = blinding value */
+         /* find s = (e + xr)/k */
+         if ((err = mp_mulmod(pubkey.k, b, p, pubkey.k)) != CRYPT_OK)      { goto error; } /* k = kb */
+         if ((err = mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK)         { goto error; } /* k = 1/kb */
+         if ((err = mp_mulmod(key->k, r, p, s)) != CRYPT_OK)               { goto error; } /* s = xr */
+         if ((err = mp_mulmod(pubkey.k, s, p, s)) != CRYPT_OK)             { goto error; } /* s = xr/kb */
+         if ((err = mp_mulmod(pubkey.k, e, p, e)) != CRYPT_OK)             { goto error; } /* e = e/kb */
+         if ((err = mp_add(e, s, s)) != CRYPT_OK)                          { goto error; } /* s = e/kb + xr/kb */
+         if ((err = mp_mulmod(s, b, p, s)) != CRYPT_OK)                    { goto error; } /* s = b(e/kb + xr/kb) = (e + xr)/k */
+         ecc_free(&pubkey);
+         if (mp_iszero(s) == LTC_MP_NO) {
+            break;
+         }
       }
    } while (--max_iterations > 0);
 
@@ -112,17 +115,17 @@
    }
    else {
       /* store as ASN.1 SEQUENCE { r, s -- integer } */
-   err = der_encode_sequence_multi(out, outlen,
-                             LTC_ASN1_INTEGER, 1UL, r,
-                             LTC_ASN1_INTEGER, 1UL, s,
-                             LTC_ASN1_EOL, 0UL, NULL);
+      err = der_encode_sequence_multi(out, outlen,
+                               LTC_ASN1_INTEGER, 1UL, r,
+                               LTC_ASN1_INTEGER, 1UL, s,
+                               LTC_ASN1_EOL, 0UL, NULL);
    }
    goto errnokey;
 error:
    ecc_free(&pubkey);
 errnokey:
-   mp_clear_multi(r, s, p, e, NULL);
-   return err;   
+   mp_clear_multi(r, s, p, e, b, NULL);
+   return err;
 }
 
 /**