init: v1.0.0

internal/kdf/sm_kdf.go

@@ -0,0 +1,54 @@
+///
+/// Copyright (c) 2018 xdx. All rights reserved.
+///
+/// \file: kdf.go
+///
+/// \brief: SM2和SM9标准中定义的密钥扩展函数，哈希函数使用SM3。
+///
+/// \author: xdx
+///
+
+package kdf
+
+import (
+	"encoding/binary"
+
+	"xdx.jelly/xgcl/sm/sm3"
+)
+
+type smKDF struct {
+}
+
+// Kdf 密钥派生函数
+// 省略了检查len(out)-out是调用者已分配好，几乎不会出现len(out)=128G的情况。
+// const maxKDFLen = 0x1fffffffe0 //( (1 << 32) - 1 ) * 32
+// out必须分配好空间。KDF填充out[:len(out)],输入ins可以包括多组
+// 函数内部不会对out的底层数组做重分配
+// 目前不返回错误
+func (*smKDF) Kdf(out []byte, inputs ...[]byte) error {
+	s0 := sm3.NewDigest()
+	for _, in := range inputs {
+		s0.Write(in)
+	}
+
+	buf := make([]byte, 4)
+	var ct uint32 = 1
+	pos := 0
+	s := sm3.NewDigest()
+	for pos <= int(len(out))-sm3.Size {
+		// make a copy
+		*s = *s0
+		binary.BigEndian.PutUint32(buf, ct)
+		ct++
+		s.Write(buf[:4])
+		s.Sum(out[:pos])
+		pos += sm3.Size
+	}
+	if pos < len(out) {
+		binary.BigEndian.PutUint32(buf, ct)
+		s0.Write(buf[:4])
+		d := s0.Sum(nil)
+		copy(out[pos:], d)
+	}
+	return nil
+}