From 33bee1b86a6b28ec543c96faecfbbc194552c0d6 Mon Sep 17 00:00:00 2001
From: MITSUNARI Shigeo <herumi@nifty.com>
Date: Tue, 11 Sep 2018 13:57:18 +0900
Subject: update comment for subgroup attack

---
 readme.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/readme.md b/readme.md
index 64134d3..a2d6d52 100644
--- a/readme.md
+++ b/readme.md
@@ -130,6 +130,18 @@ bool Sign::verify(const PublicKey& pub) const;
 
 Verify a public key by pop.
 
+# Check the order of a point
+
+deserializer functions check whether a point has correct order and
+the cost is heavy for especially G2.
+If you do not want to check it, then call
+```
+void blsSignatureVerifyOrder(false);
+void blsPublicKeyVerifyOrder(false);
+```
+
+cf. subgroup attack
+
 # Go
 ```
 make test_go
-- 
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