mirror of
https://github.com/emmansun/gmsm.git
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58 lines
1.7 KiB
Go
58 lines
1.7 KiB
Go
// Copyright 2024 Sun Yimin. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package cfca
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import (
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"crypto/cipher"
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"errors"
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"github.com/emmansun/gmsm/padding"
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"github.com/emmansun/gmsm/sm3"
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"github.com/emmansun/gmsm/sm4"
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)
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// NewSM4CBCBlockMode creates a new SM4-CBC block mode with the password.
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func NewSM4CBCBlockMode(password []byte, isEncrypter bool) (cipher.BlockMode, error) {
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if len(password) == 0 {
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return nil, errors.New("cfca: invalid password")
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}
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ivkey := sm3.Kdf(password, 32)
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block, err := sm4.NewCipher(ivkey[16:])
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if err != nil {
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return nil, err
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}
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if isEncrypter {
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return cipher.NewCBCEncrypter(block, ivkey[:16]), nil
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}
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return cipher.NewCBCDecrypter(block, ivkey[:16]), nil
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}
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// EncryptBySM4CBC encrypts the data with the password using SM4-CBC algorithm.
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// Corresponds to the cfca.sadk.util.encryptMessageBySM4 method.
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func EncryptBySM4CBC(plaintext, password []byte) ([]byte, error) {
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mode, err := NewSM4CBCBlockMode(password, true)
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if err != nil {
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return nil, err
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}
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pkcs7 := padding.NewPKCS7Padding(uint(mode.BlockSize()))
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plaintext = pkcs7.Pad(plaintext)
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ciphertext := make([]byte, len(plaintext))
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mode.CryptBlocks(ciphertext, plaintext)
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return ciphertext, nil
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}
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// DecryptBySM4CBC decrypts the data with the password using SM4-CBC algorithm.
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// Corresponds to the cfca.sadk.util.decryptMessageBySM4 method.
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func DecryptBySM4CBC(ciphertext, password []byte) ([]byte, error) {
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mode, err := NewSM4CBCBlockMode(password, false)
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if err != nil {
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return nil, err
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}
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plaintext := make([]byte, len(ciphertext))
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mode.CryptBlocks(plaintext, ciphertext)
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pkcs7 := padding.NewPKCS7Padding(uint(mode.BlockSize()))
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return pkcs7.Unpad(plaintext)
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}
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