Merge pull request #2511 from tmael/BN_bn2hex

Fix for hex digits with fastmath and normal integer

tests/api.c

@@ -24123,7 +24123,11 @@ static void test_wolfSSL_X509_get_serialNumber(void)
     X509_free(x509); /* free's a */
 
     AssertNotNull(serialHex = BN_bn2hex(bn));
+#ifndef WC_DISABLE_RADIX_ZERO_PAD
+    AssertStrEQ(serialHex, "01");
+#else
     AssertStrEQ(serialHex, "1");
+#endif
     OPENSSL_free(serialHex);
 
     AssertIntEQ(BN_get_word(bn), 1);

wolfcrypt/src/integer.c

@@ -5233,7 +5233,13 @@ int mp_toradix (mp_int *a, char *str, int radix)
         *str++ = mp_s_rmap[d];
         ++digs;
     }
-
+#ifndef WC_DISABLE_RADIX_ZERO_PAD
+    /* For hexadecimal output, add zero padding when number of digits is odd */
+    if ((digs & 1) && (radix == 16)) {
+        *str++ = mp_s_rmap[0];
+        ++digs;
+    }
+#endif
     /* reverse the digits of the string.  In this case _s points
      * to the first digit [excluding the sign] of the number]
      */

wolfcrypt/src/tfm.c

@@ -4779,7 +4779,13 @@ int mp_toradix (mp_int *a, char *str, int radix)
         *str++ = fp_s_rmap[d];
         ++digs;
     }
-
+#ifndef WC_DISABLE_RADIX_ZERO_PAD
+    /* For hexadecimal output, add zero padding when number of digits is odd */
+    if ((digs & 1) && (radix == 16)) {
+        *str++ = fp_s_rmap[0];
+        ++digs;
+    }
+#endif
     /* reverse the digits of the string.  In this case _s points
      * to the first digit [excluding the sign] of the number]
      */