我尝试使用OpenSSL兼容格式在Win OS中加密（aes-128-cbc），并使用作为OpenSSL包装的Poco :: Crypto在Linux OS上解密。 我使用了一个pwd和盐。
深入了解Stack Overflow，OpenSSL和Poco我发现：
1）从Win端（我使用C＃方法）需要创建一个带有标题＆＃34; Salted__1 ..... 8 ＆＃34;字节，其中1..8字节是随机模式下生成的盐。标头字节总数= 16.事实上，OpenSSL函数EVP_BytesToKey(..)从标头中提取的盐生成密钥。我将所有字节（标题+盐+加密）保存在一个文件中。
我要感谢Antanas Veiverys在https://antanas.veiverys.com/encrypt-data-with-net-decrypt-with-openssl/的代码。我使用他的课程如下（片段）：
public static class AESEncryption
{
private static byte[] randomBytes(int size)
{
byte[] array = new byte[size];
new Random().NextBytes(array);
return array;
}
/// Encrypt a string
public static string Encrypt(string plainText, string password)
{
byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
byte[] encryptedBytes = Encrypt(plainTextBytes, password);
return Convert.ToBase64String(encryptedBytes);
}
public static byte[] Encrypt(byte[] plainTextBytes, string password)
{
byte[] salt = randomBytes(8);
// if salt is same during every encryption, same key is used. May be useful for testing, must not be used in production code
//salt = new byte[8]; //set {0,0...}
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
MD5 md5 = MD5.Create();
int preKeyLength = password.Length + salt.Length;
byte[] preKey = new byte[preKeyLength];
Buffer.BlockCopy(passwordBytes, 0, preKey, 0, passwordBytes.Length);
Buffer.BlockCopy(salt, 0, preKey, passwordBytes.Length, salt.Length);
byte[] key = md5.ComputeHash(preKey);
int preIVLength = key.Length + preKeyLength;
byte[] preIV = new byte[preIVLength];
Buffer.BlockCopy(key, 0, preIV, 0, key.Length);
Buffer.BlockCopy(preKey, 0, preIV, key.Length, preKey.Length);
byte[] iv = md5.ComputeHash(preIV);
md5.Clear();
md5 = null;
//debug
Console.WriteLine("Key:");
foreach(byte b in key){
Console.WriteLine("Hex: {0:X}", b);
}
Console.WriteLine("--------------------");
AesManaged aes = new AesManaged();
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
aes.KeySize = 128;
aes.BlockSize = 128;
aes.Key = key;
aes.IV = iv;
byte[] encrypted = null;
using (ICryptoTransform Encryptor = aes.CreateEncryptor())
{
using (MemoryStream MemStream = new MemoryStream())
{
using (CryptoStream CryptoStream = new CryptoStream(MemStream, Encryptor, CryptoStreamMode.Write))
{
CryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
CryptoStream.FlushFinalBlock();
encrypted = MemStream.ToArray();
CryptoStream.Close();
}
MemStream.Close();
}
}
aes.Clear();
int resultLength = encrypted.Length + 8 + 8;
byte[] salted = Encoding.UTF8.GetBytes("Salted__");
byte[] result = new byte[resultLength];
Buffer.BlockCopy(salted, 0, result, 0, salted.Length);
Buffer.BlockCopy(salt, 0, result, 8, salt.Length);
Buffer.BlockCopy(encrypted, 0, result, 16, encrypted.Length);
return result;
}
2）此时，要在Poco中创建右键，我必须将ItererationCount = 1而不是2000设置为默认值：
CipherKeyImpl
{
const std::string & name,
const std::string & passphrase,
const std::string & salt,
int iterationCount = 2000
);
通过这种方式，我将从头文件中提取salt，生成密钥并尝试使用此代码进行解密：
ifstream myfile(FILE_TO_DECRYPT, ios::binary);
//get the length
myfile.seekg(0, myfile.end);
int length = myfile.tellg();
myfile.seekg(0, myfile.beg);
//read the encrypted file
char buffer = new char[lenght]();
myfile.read(buffer, lenght);
//get the salt from the header
string toDecrypt(buffer);
string salt = toDecrypt.substr(8, 8); //the salt is 8 bytes start from 8th in header in OpenSSL
//decode
CipherFactory& factory = CipherFactory::defaultFactory();
Chipher key("aes-128-cbc", PASSWORD, salt, 1);
//key is well generated!
unique_ptr<Cipher> uptrCipher(factory.createCipher(key));
string decrypted = uptrChiper->decryptString(toDecrypt, Cipher::ENC_BASE64);
我检查了盐和密钥是否正常：它们与我在C＃代码中使用的相同。
最后一行产生错误：＆＃34; EVP_DecryptFinal_ex：错误的最终块长度。＆＃34;
我不知道我错在哪里。任何帮助表示赞赏。
答案 0 :(得分：1)
有两个问题。首先，我犯了一个错误。我需要传递给解密方法只有没有标题的字节：所以我补充说：
toDecrypt = toDectrypt.substr(16);
代码，否则解密不起作用，因为标题。
其次，我使用了ENC_BASE64，所以我需要在解密前对字符串中的字节进行编码。为此，我使用了Poco :: Base64Encoder。
此时......它有效！我使用C＃中的AES-128-CBC在Windows上加密，并使用C ++，Poco和OpenSSL格式在Linux上解密。我道歉：代码可能更好，但我需要时间来优化它。
#include <iostream>
#include <memory>
#include <fstream>
#include <sstream>
#include "Poco/Crypto/OpenSSLInitializer.h"
#include "Poco/Crypto/Cipher.h"
#include "Poco/Crypto/CipherKey.h"
#include "Poco/Crypto/CipherFactory.h"
#include "Poco/Base64Encoder.h"
using namespace std;
using namespace Poco;
using namespace Poco::Net;
using namespace Poco::Crypto;
const string FILE_TO_DECRYPT = {"/home/myuser/Documents/CryptoTest/EncryptedText.txt"};
void decrypt() {
OpenSSLInitializer();
string PASSWORD = "1234567890123456"; //example! I know that is FORBIDDEN to embed the pwd :-)
try {
const size_t len = 17;
std::ifstream fileImage(FILE_TO_DECRYPT);
if(!fileImage.good())
return;
//get lenght of file
fileImage.seekg(0, fileImage.end);
int length = fileImage.tellg();
fileImage.seekg(0, fileImage.beg);
char* buffer = new char[length];
fileImage.read(buffer, length);
ostringstream ostringstr;
Base64Encoder base64 (ostringstr);
string toDecrypt(buffer, length);
string salt = toDecrypt.substr(8, 8);
cout<<endl<<"salt length = "<<salt.length()<<endl;
//Debug
for(unsigned k = 0; k < salt.length(); k++)
cout<<endl<<"["<<k<<"]"<<hex<<(unsigned)(unsigned char)salt[k]<<flush;
CipherFactory& factory = CipherFactory::defaultFactory();
CipherKey key("aes-128-cbc", PASSWORD, salt, 1);
auto k = key.getKey();
//Debug
cout<<endl<<"KEY---";
for(auto i : k)
cout<<endl<<std::hex<<(unsigned)i<<std::dec<<flush;
unique_ptr<Cipher> uptrCipher(factory.createCipher(key));
toDecrypt=toDecrypt.substr(16);
base64<<toDecrypt;
base64.close();
string toDecryptEncoded = ostringstr.str();
string decrypted = uptrCipher->decryptString(toDecryptEncoded, Cipher::ENC_BASE64); //Cipher::ENC_BASE64);
cout<<endl<<"Decrypted= "<<decrypted<<endl;
delete []buffer;
}
catch(const Poco::Exception& exc)
{
cerr << endl<< "Decryption error: " << exc.message() << endl;
delete []buffer; //in case of error...
}
}