Question

我正在玩AES并将iv和派生密钥写入文件，以便我以后用它来解密......

以下功能加密文件并将iv和派生密钥保存到文件中，它还将加密文本保存到单独的文件中：

void MainWindow::on_button_encrypt() try
{
    using namespace std;
    using namespace Gtk;
    using namespace CryptoPP;

    fstream file;

    file.open(m_file_name + ".aes", std::ios::out | std::ios::trunc);
    if (file.is_open())
    {
        // get the plain password:
        SecByteBlock password;
        password_dialog get_passwd(password);
        get_passwd.run();


        // generate random salt
        const int SALT_SIZE = 32;
        SecByteBlock salt(SALT_SIZE);
        AutoSeededRandomPool prng;
        prng.GenerateBlock(salt.BytePtr(), SALT_SIZE);


        // derive a key from password and salt:
        SecByteBlock key(AES::DEFAULT_KEYLENGTH);
        PKCS5_PBKDF2_HMAC<SHA512> gen;
        gen.DeriveKey(key.BytePtr(), key.size(), 1, password.BytePtr(), password.size(), salt.BytePtr(), salt.size(), 200);


        // genereate random iv:
        SecByteBlock iv(AES::BLOCKSIZE);
        OS_GenerateRandomBlock(false, iv.BytePtr(), AES::BLOCKSIZE);


        // encrypt plain text:
        AES::Encryption enc(key.BytePtr(), AES::DEFAULT_KEYLENGTH);
        CBC_Mode_ExternalCipher::Encryption mode(enc, iv);

        string cipher_text;
        StringSink* sink = new StringSink(cipher_text);
        StreamTransformationFilter encryptor(mode, sink);

        string plain_text = m_file_buffer->get_text();
        encryptor.Put(reinterpret_cast<const byte*>(plain_text.c_str()), plain_text.length() + 1);
        encryptor.MessageEnd();

        // write the result:
        file << cipher_text.c_str();
        file.close();
        file.open(m_file_name + ".key", std::ios::out | std::ios::trunc);
        file << key << '\n' << iv;
        file.close();
   }
}
// catch ...

上述函数将iv和派生密钥写入文件。

0000000002F9F140

0000000002F9F4E0

以下函数应该读取文件并使用* .key文件解密它：

void MainWindow::on_button_decrypt()
{
    using namespace std;
    using namespace CryptoPP;
    Gtk::MessageDialog info("Info");

    fstream file;
    file.open("decrypted.txt", ios::out | ios::trunc);
    if (file.is_open())
    {
        // read the key:
        fstream stream;
        string input;

        SecByteBlock key(AES::DEFAULT_KEYLENGTH);
        SecByteBlock iv(AES::BLOCKSIZE);


        stream.open("test.txt.key", std::ios::in);

        if (stream.is_open())
        {
            getline(stream, input);
            key.Assign(reinterpret_cast<const byte*>(input.c_str()), input.size());
            input.clear();
            getline(stream, input);
            iv.Assign(reinterpret_cast<const byte*>(input.c_str()), input.size());
        }
        else
        {
            info.set_secondary_text("can't read key file");
            info.run();
            return;
        }


        // decrypt:
        AES::Decryption dec(key, AES::DEFAULT_KEYLENGTH);
        CBC_Mode_ExternalCipher::Decryption mode(dec, iv);

        string plain_text;
        StringSink* sink = new StringSink(plain_text);
        StreamTransformationFilter decryptor(mode, sink);

        try
        {
            // get encrypted text from buffer (obtained from other function):
            string cipher_text = m_file_buffer->get_text();
            decryptor.Put(reinterpret_cast<const byte*>(cipher_text.c_str()), cipher_text.size());
            decryptor.MessageEnd();
            file << plain_text;
            file.close();
        }
        catch (CryptoPP::Exception& ex)
        {
            info.set_secondary_text(ex.what());
            info.run();
        }
    }
}

CryptoPP在解密时说出了异常：

FileTransformationFilter：密文长度不是块大小的倍数。

如果在第一个函数（on_btn_encrypt（））中完成解密过程，它不会抛出任何东西，那里没有读取文件，所以它看起来我有读取加密文件的问题但不知道怎么办？

这是加密文件的内容：的＆安培;`OôÍoYjÜMe×Q°Þ

明文是： 一些文字

你看到我在这里失踪了吗？非常感谢！

修改

这里是修改，解决了Qmick和Artjom提出的问题：

加密

// encrypt the file:
AES::Encryption enc(key.BytePtr(), AES::DEFAULT_KEYLENGTH);
CBC_Mode_ExternalCipher::Encryption mode(enc, iv);

string file = m_file_name + ".aes";
FileSink* sink = new FileSink(file.c_str());
StreamTransformationFilter encryptor(mode, sink);

string plain_text = m_file_buffer->get_text();
encryptor.Put(reinterpret_cast<const byte*>(plain_text.c_str()), plain_text.length());
encryptor.MessageEnd();


// write the key:
file = m_file_name + ".key";
FileSink* out = new FileSink(file.c_str());
Base64Encoder* base64_enc = new Base64Encoder;
base64_enc->Attach(out);
base64_enc->Put(key.BytePtr(), key.size());
base64_enc->MessageEnd();



// write the iv:
file = m_file_name + ".iv";
FileSink* out2 = new FileSink(file.c_str());
Base64Encoder* base64_enc2 = new Base64Encoder;
base64_enc2->Attach(out2);
base64_enc2->Put(iv.BytePtr(), iv.size());
base64_enc2->MessageEnd();

解密：

//
// read key
//
string store_key;
StringSink* string_key_in = new StringSink(store_key);
Base64Decoder* base64_key_dec = new Base64Decoder(string_key_in);

string file = "test.txt.key";
FileSource* file_key_in = new FileSource(file.c_str(), true, base64_key_dec);

SecByteBlock key(AES::DEFAULT_KEYLENGTH);
key.Assign(reinterpret_cast<const byte*>(store_key.c_str()), store_key.size());




//
// read iv
//
string store_iv;
StringSink* string_iv_in = new StringSink(store_iv);
Base64Decoder* base64_iv_dec = new Base64Decoder(string_iv_in);

file = "test.txt.iv";
FileSource* file_iv_in = new FileSource(file.c_str(), true, base64_iv_dec);

SecByteBlock iv(AES::BLOCKSIZE);
iv.Assign(reinterpret_cast<const byte*>(store_iv.c_str()), store_iv.size());



// read ciphertext:
string store_ciphertext;
StringSink* ciphertext_in = new StringSink(store_ciphertext);

file = m_file_name;
FileSource* file_ciphertext_in = new FileSource(file.c_str(), true, ciphertext_in);

SecByteBlock cipher_text;
cipher_text.Assign(reinterpret_cast<const byte*>(store_ciphertext.c_str()), store_ciphertext.size());



//
// decrypt:
//
AES::Decryption dec(key, AES::DEFAULT_KEYLENGTH);
CBC_Mode_ExternalCipher::Decryption mode(dec, iv);

file = "decrypted.txt";
FileSink* sink = new FileSink(file.c_str());
StreamTransformationFilter decryptor(mode, sink);

decryptor.Put(cipher_text.BytePtr(), cipher_text.size());
decryptor.MessageEnd();

Answer 1

没有保证密码文本不会包含\n之类的转义序列，这会使getline()出错字符串（截断）。

因此建议将密文转换为十六进制或其他内容以避免转义序列。

AES加密C ++（无法解密加密文件）

1 个答案: