86 lines
2.1 KiB
Go
86 lines
2.1 KiB
Go
package cryptox
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/md5"
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"crypto/sha256"
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"encoding/base64"
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"encoding/hex"
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"fmt"
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"time"
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)
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// generateKey: SHA256(secret)[:32]
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func generateKey(secret string) []byte {
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h := sha256.Sum256([]byte(secret))
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return h[:32]
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}
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// generateIv: SHA256(hex(md5(nonce)) + secret)[:16]
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func generateIv(nonce, secret string) []byte {
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md5h := md5.Sum([]byte(nonce))
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md5hex := hex.EncodeToString(md5h[:])
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sha := sha256.Sum256([]byte(md5hex + secret))
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return sha[:16]
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}
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// Encrypt 加密明文，返回 base64密文 和 nonce（hex(UnixNano)）
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func Encrypt(plaintext []byte, secret string) (dataB64 string, nonce string, err error) {
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nonce = fmt.Sprintf("%x", time.Now().UnixNano())
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key := generateKey(secret)
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iv := generateIv(nonce, secret)
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block, err := aes.NewCipher(key)
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if err != nil {
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return
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}
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padded := pkcs7Pad(plaintext, aes.BlockSize)
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mode := cipher.NewCBCEncrypter(block, iv)
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dst := make([]byte, len(padded))
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mode.CryptBlocks(dst, padded)
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dataB64 = base64.StdEncoding.EncodeToString(dst)
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return
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}
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// Decrypt 解密，nonce 用于派生 IV
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func Decrypt(dataB64, secret, nonce string) ([]byte, error) {
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ciphertext, err := base64.StdEncoding.DecodeString(dataB64)
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if err != nil {
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return nil, err
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}
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key := generateKey(secret)
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iv := generateIv(nonce, secret)
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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 != 0 {
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return nil, fmt.Errorf("ciphertext length not multiple of block size")
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}
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mode := cipher.NewCBCDecrypter(block, iv)
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dst := make([]byte, len(ciphertext))
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mode.CryptBlocks(dst, ciphertext)
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return pkcs7Unpad(dst)
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}
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func pkcs7Pad(data []byte, blockSize int) []byte {
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pad := blockSize - len(data)%blockSize
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padding := make([]byte, pad)
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for i := range padding {
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padding[i] = byte(pad)
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}
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return append(data, padding...)
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}
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func pkcs7Unpad(data []byte) ([]byte, error) {
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if len(data) == 0 {
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return nil, fmt.Errorf("empty data")
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}
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pad := int(data[len(data)-1])
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if pad == 0 || pad > aes.BlockSize {
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return nil, fmt.Errorf("invalid padding size: %d", pad)
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}
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return data[:len(data)-pad], nil
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}
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