89 lines
2.0 KiB
Go
89 lines
2.0 KiB
Go
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package aeshelper
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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/md5"
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"crypto/rand"
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"encoding/base64"
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"io"
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)
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// Encrypt text with the passphrase
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func Encrypt(text string, passphrase string) string {
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salt := make([]byte, 8)
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if _, err := io.ReadFull(rand.Reader, salt); err != nil {
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panic(err.Error())
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}
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key, iv := DeriveKeyAndIv(passphrase, string(salt))
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block, err := aes.NewCipher([]byte(key))
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if err != nil {
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panic(err)
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}
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pad := PKCS7Padding([]byte(text), block.BlockSize())
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ecb := cipher.NewCBCEncrypter(block, []byte(iv))
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encrypted := make([]byte, len(pad))
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ecb.CryptBlocks(encrypted, pad)
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return base64.StdEncoding.EncodeToString([]byte("Salted__" + string(salt) + string(encrypted)))
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}
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// Decrypt encrypted text with the passphrase
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func Decrypt(encrypted string, passphrase string) string {
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ct, _ := base64.StdEncoding.DecodeString(encrypted)
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if len(ct) < 16 || string(ct[:8]) != "Salted__" {
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return ""
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}
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salt := ct[8:16]
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ct = ct[16:]
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key, iv := DeriveKeyAndIv(passphrase, string(salt))
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block, err := aes.NewCipher([]byte(key))
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if err != nil {
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panic(err)
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}
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cbc := cipher.NewCBCDecrypter(block, []byte(iv))
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dst := make([]byte, len(ct))
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cbc.CryptBlocks(dst, ct)
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return string(PKCS7Trimming(dst))
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}
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// PKCS7Padding PKCS7Padding
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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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// PKCS7Trimming PKCS7Trimming
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func PKCS7Trimming(encrypt []byte) []byte {
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padding := encrypt[len(encrypt)-1]
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return encrypt[:len(encrypt)-int(padding)]
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}
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// DeriveKeyAndIv DeriveKeyAndIv
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func DeriveKeyAndIv(passphrase string, salt string) (string, string) {
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salted := ""
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dI := ""
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for len(salted) < 48 {
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md := md5.New()
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md.Write([]byte(dI + passphrase + salt))
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dM := md.Sum(nil)
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dI = string(dM[:16])
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salted = salted + dI
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}
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key := salted[0:32]
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iv := salted[32:48]
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return key, iv
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}
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