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