मुझे C # के लिए एक गो कार्यक्रम को पोर्ट करने की कोशिश में एक ही समस्या थी। इसका मतलब है कि गो कार्यक्रम के साथ बहुत सारे डेटा पहले से ही एन्क्रिप्ट किए गए हैं। यह डेटा अब C # के साथ डिक्रिप्ट किया जाना चाहिए।
अंतिम समाधान PaddingMode.None
या बल्कि था PaddingMode.Zeros
।
गो में क्रिप्टोग्राफिक तरीके:
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
}
... तथा ...
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
}
}
अब, C # में डिक्रिप्शन:
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;
}
पैडिंग के साथ समस्या को कैसे समझाया जा सकता है? एन्क्रिप्शन से पहले गो कार्यक्रम पेडिंग की जाँच करता है:
// 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
}
महत्वपूर्ण हिस्सा यह है:
enhanced := make([]byte, numberNecessaryBlocks*aes.BlockSize)
copy(enhanced, secretBytesDecrypted)
एक नई सरणी एक उपयुक्त लंबाई के साथ बनाई गई है, ताकि लंबाई ब्लॉक आकार के एक से अधिक हो। यह नया सरणी शून्य से भरा है। कॉपी विधि फिर मौजूदा डेटा को इसमें कॉपी करता है। यह सुनिश्चित किया जाता है कि नया सरणी मौजूदा डेटा से बड़ा है। तदनुसार, सरणी के अंत में शून्य हैं।
इस प्रकार, सी # कोड का उपयोग कर सकते हैं PaddingMode.Zeros
। विकल्प PaddingMode.None
सिर्फ किसी भी पैडिंग को नजरअंदाज करता है, जो काम भी करता है। मुझे उम्मीद है कि यह उत्तर किसी के लिए भी उपयोगी है, जिसे Go से C #, आदि के लिए कोड पोर्ट करना होगा।