我在尝试将 Go 程序移植到 C# 时遇到了同样的问题。这意味着很多数据已经被 Go 程序加密了。现在必须使用 C# 解密此数据。
最终的解决方案是PaddingMode.None 或者更确切地说是PaddingMode.Zeros。
Go 中的加密方法：
import (
"crypto/aes"
"crypto/cipher"
"crypto/sha1"
"encoding/base64"
"io/ioutil"
"log"
"golang.org/x/crypto/pbkdf2"
)
func decryptFile(filename string, saltBytes []byte, masterPassword []byte) (artifact string) {
const (
keyLength int = 256
rfc2898Iterations int = 6
)
var (
encryptedBytesBase64 []byte // The encrypted bytes as base64 chars
encryptedBytes []byte // The encrypted bytes
)
// Load an encrypted file:
if bytes, bytesErr := ioutil.ReadFile(filename); bytesErr != nil {
log.Printf("[%s] There was an error while reading the encrypted file: %s\n", filename, bytesErr.Error())
return
} else {
encryptedBytesBase64 = bytes
}
// Decode base64:
decodedBytes := make([]byte, len(encryptedBytesBase64))
if countDecoded, decodedErr := base64.StdEncoding.Decode(decodedBytes, encryptedBytesBase64); decodedErr != nil {
log.Printf("[%s] An error occur while decoding base64 data: %s\n", filename, decodedErr.Error())
return
} else {
encryptedBytes = decodedBytes[:countDecoded]
}
// Derive key and vector out of the master password and the salt cf. RFC 2898:
keyVectorData := pbkdf2.Key(masterPassword, saltBytes, rfc2898Iterations, (keyLength/8)+aes.BlockSize, sha1.New)
keyBytes := keyVectorData[:keyLength/8]
vectorBytes := keyVectorData[keyLength/8:]
// Create an AES cipher:
if aesBlockDecrypter, aesErr := aes.NewCipher(keyBytes); aesErr != nil {
log.Printf("[%s] Was not possible to create new AES cipher: %s\n", filename, aesErr.Error())
return
} else {
// CBC mode always works in whole blocks.
if len(encryptedBytes)%aes.BlockSize != 0 {
log.Printf("[%s] The encrypted data's length is not a multiple of the block size.\n", filename)
return
}
// Reserve memory for decrypted data. By definition (cf. AES-CBC), it must be the same lenght as the encrypted data:
decryptedData := make([]byte, len(encryptedBytes))
// Create the decrypter:
aesDecrypter := cipher.NewCBCDecrypter(aesBlockDecrypter, vectorBytes)
// Decrypt the data:
aesDecrypter.CryptBlocks(decryptedData, encryptedBytes)
// Cast the decrypted data to string:
artifact = string(decryptedData)
}
return
}
...和...
import (
"crypto/aes"
"crypto/cipher"
"crypto/sha1"
"encoding/base64"
"github.com/twinj/uuid"
"golang.org/x/crypto/pbkdf2"
"io/ioutil"
"log"
"math"
"os"
)
func encryptFile(filename, artifact string, masterPassword []byte) (status bool) {
const (
keyLength int = 256
rfc2898Iterations int = 6
)
status = false
secretBytesDecrypted := []byte(artifact)
// Create new salt:
saltBytes := uuid.NewV4().Bytes()
// Derive key and vector out of the master password and the salt cf. RFC 2898:
keyVectorData := pbkdf2.Key(masterPassword, saltBytes, rfc2898Iterations, (keyLength/8)+aes.BlockSize, sha1.New)
keyBytes := keyVectorData[:keyLength/8]
vectorBytes := keyVectorData[keyLength/8:]
// Create an AES cipher:
if aesBlockEncrypter, aesErr := aes.NewCipher(keyBytes); aesErr != nil {
log.Printf("[%s] Was not possible to create new AES cipher: %s\n", filename, aesErr.Error())
return
} else {
// CBC mode always works in whole blocks.
if len(secretBytesDecrypted)%aes.BlockSize != 0 {
numberNecessaryBlocks := int(math.Ceil(float64(len(secretBytesDecrypted)) / float64(aes.BlockSize)))
enhanced := make([]byte, numberNecessaryBlocks*aes.BlockSize)
copy(enhanced, secretBytesDecrypted)
secretBytesDecrypted = enhanced
}
// Reserve memory for encrypted data. By definition (cf. AES-CBC), it must be the same lenght as the plaintext data:
encryptedData := make([]byte, len(secretBytesDecrypted))
// Create the encrypter:
aesEncrypter := cipher.NewCBCEncrypter(aesBlockEncrypter, vectorBytes)
// Encrypt the data:
aesEncrypter.CryptBlocks(encryptedData, secretBytesDecrypted)
// Encode base64:
encodedBytes := make([]byte, base64.StdEncoding.EncodedLen(len(encryptedData)))
base64.StdEncoding.Encode(encodedBytes, encryptedData)
// Allocate memory for the final file's content:
fileContent := make([]byte, len(saltBytes))
copy(fileContent, saltBytes)
fileContent = append(fileContent, 10)
fileContent = append(fileContent, encodedBytes...)
// Write the data into a new file. This ensures, that at least the old version is healthy in case that the
// computer hangs while writing out the file. After a successfully write operation, the old file could be
// deleted and the new one could be renamed.
if writeErr := ioutil.WriteFile(filename+"-update.txt", fileContent, 0644); writeErr != nil {
log.Printf("[%s] Was not able to write out the updated file: %s\n", filename, writeErr.Error())
return
} else {
if renameErr := os.Rename(filename+"-update.txt", filename); renameErr != nil {
log.Printf("[%s] Was not able to rename the updated file: %s\n", fileContent, renameErr.Error())
} else {
status = true
return
}
}
return
}
}
现在，用 C# 解密：
public static string FromFile(string filename, byte[] saltBytes, string masterPassword)
{
var iterations = 6;
var keyLength = 256;
var blockSize = 128;
var result = string.Empty;
var encryptedBytesBase64 = File.ReadAllBytes(filename);
// bytes -> string:
var encryptedBytesBase64String = System.Text.Encoding.UTF8.GetString(encryptedBytesBase64);
// Decode base64:
var encryptedBytes = Convert.FromBase64String(encryptedBytesBase64String);
var keyVectorObj = new Rfc2898DeriveBytes(masterPassword, saltBytes.Length, iterations);
keyVectorObj.Salt = saltBytes;
Span<byte> keyVectorData = keyVectorObj.GetBytes(keyLength / 8 + blockSize / 8);
var key = keyVectorData.Slice(0, keyLength / 8);
var iv = keyVectorData.Slice(keyLength / 8);
var aes = Aes.Create();
aes.Padding = PaddingMode.Zeros;
// or ... aes.Padding = PaddingMode.None;
var decryptor = aes.CreateDecryptor(key.ToArray(), iv.ToArray());
var decryptedString = string.Empty;
using (var memoryStream = new MemoryStream(encryptedBytes))
{
using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
{
using (var reader = new StreamReader(cryptoStream))
{
decryptedString = reader.ReadToEnd();
}
}
}
return result;
}
如何解释填充问题？就在加密之前，Go 程序检查填充：
// CBC mode always works in whole blocks.
if len(secretBytesDecrypted)%aes.BlockSize != 0 {
numberNecessaryBlocks := int(math.Ceil(float64(len(secretBytesDecrypted)) / float64(aes.BlockSize)))
enhanced := make([]byte, numberNecessaryBlocks*aes.BlockSize)
copy(enhanced, secretBytesDecrypted)
secretBytesDecrypted = enhanced
}
重要的是：
enhanced := make([]byte, numberNecessaryBlocks*aes.BlockSize)
copy(enhanced, secretBytesDecrypted)
创建一个具有适当长度的新数组，因此长度是块大小的倍数。这个新数组用零填充。然后，copy 方法将现有数据复制到其中。确保新数组大于现有数据。因此，数组末尾有零。
因此，C# 代码可以使用PaddingMode.Zeros。替代 PaddingMode.None 只是忽略任何填充，这也有效。我希望这个答案对必须将代码从 Go 移植到 C# 等的任何人都有帮助。