102 lines
2.4 KiB
Go
102 lines
2.4 KiB
Go
package aes
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"fmt"
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"io"
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"math/big"
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)
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const (
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TestKey = "ROK0nAaxcsI0KRCy8VJgLlnlfjWYAOHk"
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)
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// 加密函数
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func Encrypt(plaintext, key []byte) ([]byte, error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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// 加密后的数据会比原文长，因为需要添加一些填充字节
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// PKCS#7填充
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plaintext = pkcs7Padding(plaintext, block.BlockSize())
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// 创建一个cipher.BlockMode，这里使用CBC模式
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// 需要一个iv（初始化向量），它的长度和Block的块大小相同
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ciphertext := make([]byte, aes.BlockSize+len(plaintext))
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iv := ciphertext[:aes.BlockSize]
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if _, err := io.ReadFull(rand.Reader, iv); err != nil {
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return nil, err
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}
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mode := cipher.NewCBCEncrypter(block, iv)
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mode.CryptBlocks(ciphertext[aes.BlockSize:], plaintext)
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// 返回的密文包括iv和加密后的数据
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return ciphertext, nil
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}
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// 解密函数
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func Decrypt(ciphertext, key []byte) ([]byte, error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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if len(ciphertext) < aes.BlockSize {
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return nil, fmt.Errorf("ciphertext too short")
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}
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// 提取iv
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iv := ciphertext[:aes.BlockSize]
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ciphertext = ciphertext[aes.BlockSize:]
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// 创建一个cipher.BlockMode
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mode := cipher.NewCBCDecrypter(block, iv)
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// 解密
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mode.CryptBlocks(ciphertext, ciphertext)
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// 去除PKCS#7填充
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plaintext, err := pkcs7Unpadding(ciphertext, block.BlockSize())
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if err != nil {
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return nil, err
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}
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return plaintext, nil
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}
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// PKCS#7填充
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func pkcs7Padding(ciphertext []byte, blockSize int) []byte {
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padding := blockSize - len(ciphertext)%blockSize
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padtext := bytes.Repeat([]byte{byte(padding)}, padding)
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return append(ciphertext, padtext...)
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}
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// 去除PKCS#7填充
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func pkcs7Unpadding(ciphertext []byte, blockSize int) ([]byte, error) {
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length := len(ciphertext)
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unpadding := int(ciphertext[length-1])
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if unpadding > blockSize || unpadding == 0 {
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return nil, fmt.Errorf("invalid padding")
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}
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return ciphertext[:(length - unpadding)], nil
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}
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func GenerateRandomStringCrypto(length int) (string, error) {
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const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
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var bytes = make([]byte, length)
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for i := range bytes {
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num, err := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
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if err != nil {
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return "", err
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}
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bytes[i] = charset[num.Int64()]
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}
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return string(bytes), nil
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}
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