From b15cfdfe966e6a88fa2356872ef12c807853e1f8 Mon Sep 17 00:00:00 2001
From: Sun Yimin <emmansun@users.noreply.github.com>
Date: Mon, 3 Jan 2022 14:25:17 +0800
Subject: [PATCH] Created GCM for SM4 (markdown)

---
 GCM-for-SM4.md | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 GCM-for-SM4.md

diff --git a/GCM-for-SM4.md b/GCM-for-SM4.md
new file mode 100644
index 0000000..0864585
--- /dev/null
+++ b/GCM-for-SM4.md
@@ -0,0 +1,15 @@
+为sm4实现的GCM汇编代码是从AES GCM实现中摘抄的。主要为以下三个函数：
+'''
+	//go:noescape
+func precomputeTableAsm(productTable *[256]byte, src *[16]byte)
+
+//go:noescape
+func gcmSm4Data(productTable *[256]byte, data []byte, T *[16]byte)
+
+//go:noescape
+func gcmSm4Finish(productTable *[256]byte, tagMask, T *[16]byte, pLen, dLen uint64)
+'''
+
+1. gcmSm4Finish没有改变，和gcmAesFinish一模一样；
+1. precomputeTableAsm和gcmAesInit的区别在于前者没有加密部分，输入参数就是加密结果；
+1. gcmSm4Data和gcmAesData的差别在于前者那个T参数同时作为输入，而后者只作为输出。
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