83 lines
2.3 KiB
Markdown
83 lines
2.3 KiB
Markdown
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# PCSK#7 填充读写流
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直接使用分块加密，往往需要手动完成填充和去填充的过程。流程较为固定，但是比较繁琐，对于文件和流的处理，不是很友好。
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PKCS#7填充和去除填充：
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- `padding.PKCS7PaddingReader` 写入结束是添加填充
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- `padding.PKCS7PaddingWriter` 读取时去除填充
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封装的填充模式加密：
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- `padding.P7BlockEnc`
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- `padding.P7BlockDecrypt`
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以上方法简化了，对文件和流类型的加密解密过程。
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## 带填充的模式加密和解密
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> 流：实现了 `io.Writer`、`io.Reader`接口的类型。
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流的SM4分块CBC模式加密：
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```go
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func main() {
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src := bytes.Repeat([]byte{7}, 16)
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srcIn := bytes.NewBuffer(src)
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encOut := bytes.NewBuffer(make([]byte, 0, 1024))
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key := make([]byte, 16)
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iv := make([]byte, 16)
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_, _ = rand.Read(key)
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_, _ = rand.Read(iv)
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fmt.Printf("key: %02X\n", key)
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fmt.Printf("iv : %02X\n", iv)
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block, err := sm4.NewCipher(key)
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if err != nil {
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panic(err)
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}
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encrypter := cipher.NewCBCEncrypter(block, iv)
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// P7填充的CBC加密
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err = padding.P7BlockEnc(encrypter, srcIn, encOut)
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if err != nil {
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panic(err)
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}
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fmt.Printf("原文: %02X\n", src)
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fmt.Printf("加密: %02X\n", encOut.Bytes())
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}
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```
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流的SM4分块CBC模式解密：
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```go
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func main() {
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/**
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key: 4C9CA3D17263F6F558D65ADB561465BD
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iv : 221908D1C4BD730BEB011319D1368E49
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原文: 07070707070707070707070707070707
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加密: 310CA2472DCE15CCC58E1BE69B876002F443556CCFB86B1BA0341B6BFBED4C1A
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*/
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encOut := bytes.NewBuffer(make([]byte, 0, 1024))
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key,_ := hex.DecodeString("4C9CA3D17263F6F558D65ADB561465BD")
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iv,_ := hex.DecodeString("221908D1C4BD730BEB011319D1368E49")
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block, err := sm4.NewCipher(key)
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if err != nil {
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panic(err)
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}
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ciphertext, _ := hex.DecodeString("310CA2472DCE15CCC58E1BE69B876002F443556CCFB86B1BA0341B6BFBED4C1A")
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cipherReader := bytes.NewReader(ciphertext)
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decrypter := cipher.NewCBCDecrypter(block, iv)
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decOut := bytes.NewBuffer(make([]byte, 0, 1024))
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err = padding.P7BlockDecrypt(decrypter, ciphertext, decOut)
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if err != nil {
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panic(err)
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}
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fmt.Printf("解密: %02X\n", decOut.Bytes())
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}
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```
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## PKCS#7填充
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见测试用例: [pkcs7_padding_io_test.go](./pkcs7_padding_io_test.go)
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