c++ - 使用Crypto++时AES/CTR解密意外停止了吗？

我正在尝试使用 Crypto ++库对AES加密和解密字节数组(vector<unsigned char>)。加密正常工作。

我的函数生成一个随机IV，并将其放在加密数据的前面。当然解密会读取IV。我修改了this答案中的代码，因此可以与我的 vector 和CTR /无填充一起使用。

程序在stfDecryptor.Put(...)行中崩溃。首先，我认为数据或IV读取不正确，但是经过检查后，情况并非如此。

我希望我在这里犯了一个非常明显的错误。

谢谢你们 :)

类电话:

//The code is not clean, i want to get it working first and then clean it up.
auto key = Helper::RandomBytes(16); //returns "byte Array" with random Bytes
auto data = Helper::UTF8String2ByteArray("HELLO WORLD!");
auto encrypted = AESCrypt::encrypt(key, data);
cout << Helper::ByteArray2HexString(key);
cout << "\r\n";
cout << Helper::ByteArray2HexString(data);
cout << "\r\n";
cout << Helper::ByteArray2HexString(encrypted);
cout << "\r\n";
auto decrypted = AESCrypt::decrypt(key, encrypted);
auto clear = Helper::ByteArray2UTF8String(decrypted);

类:

vector<unsigned char> AESCrypt::encrypt(vector<unsigned char> key_, vector<unsigned char> data)
{
    vector<unsigned char> iv_ = Helper::RandomBytes(16); //returns "byte Array" with random Bytes

    byte key[AES::DEFAULT_KEYLENGTH], iv[AES::BLOCKSIZE];

    for (size_t i = 0; i < AES::DEFAULT_KEYLENGTH; i++)
        key[i] = key_[i];
    for (size_t i = 0; i < iv_.size(); i++)
        iv[i] = iv_[i];

    AES::Encryption aesEncryption(key, AES::DEFAULT_KEYLENGTH);
    CTR_Mode_ExternalCipher::Encryption ctrEncryption(aesEncryption, iv);

    vector<unsigned char> encrypted;
    StreamTransformationFilter stfEncryptor(
        ctrEncryption,
        new VectorSink(encrypted),
        BlockPaddingSchemeDef::NO_PADDING);

    stfEncryptor.Put((const byte*)data.data(), data.size());
    stfEncryptor.MessageEnd();

    vector<unsigned char> output(encrypted.size() + 16);

    for (size_t i = 0; i < 16; i++)
        output[i] = iv[i];
    for (size_t i = 0; i < encrypted.size(); i++)
        output[16 + i] = encrypted[i];

    return output;
}

vector<unsigned char> AESCrypt::decrypt(vector<unsigned char> key_, vector<unsigned char> data_)
{
    byte key[AES::DEFAULT_KEYLENGTH], iv[AES::BLOCKSIZE];
    for (size_t i = 0; i < AES::DEFAULT_KEYLENGTH; i++)
        key[i] = key_[i];
    for (size_t i = 0; i < 16; i++)
        iv[i] = data_[i];

    vector<unsigned char> data(data_.size() - 16);
    for (size_t i = 0; i < data.size(); i++)
    {
        data[i] = data_[16 + i];
    }

    AES::Decryption aesDecryption(key, AES::DEFAULT_KEYLENGTH);
    CTR_Mode_ExternalCipher::Decryption ctrDecryption(aesDecryption, iv);

    vector<unsigned char> decrypted;
    StreamTransformationFilter stfDecryptor(
        ctrDecryption,
        new VectorSink(decrypted),
        BlockPaddingSchemeDef::NO_PADDING);

    stfDecryptor.Put((const byte*)data.data(), data.size()); //this is where it crashes
    stfDecryptor.MessageEnd();

    return decrypted;

}

这是CallStack的图片:



这是在Crypto ++库内部停止的行:

CRYPTOPP_ASSERT(m_cipher->IsForwardTransformation());

最佳答案

计数器模式(CTR)使用正向变换进行加密和解密。 “正向转换”是指加密。密钥流是通过对IV /计数器进行加密而生成的，然后将密钥流与明文或密文进行异或。

您应该更改此:

AES::Decryption aesDecryption(key, AES::DEFAULT_KEYLENGTH);
CTR_Mode_ExternalCipher::Decryption ctrDecryption(aesDecryption, iv);

对此:

AES::Encryption aesDecryption(key, AES::DEFAULT_KEYLENGTH);
CTR_Mode_ExternalCipher::Decryption ctrDecryption(aesDecryption, iv);

注意计数器模式解密使用加密器。

Wiki有一个计数器模式的示例，我们将此问答作为外部密码示例的一部分。另请参阅Crypto ++ Wiki上的CTR Mode。

这是复制器。

$ cat test.cxx
#include "cryptlib.h"
#include "secblock.h"
#include "filters.h"
#include "modes.h"
#include "aes.h"

#include <iostream>
#include <string>

int main (int argc, char* argv[])
{
    using namespace CryptoPP;

    SecByteBlock key(16), iv(16);
    std::memset(key, 0xff, key.size());
    std::memset( iv, 0x88,  iv.size());

    std::string message, encrypted, decrypted;
    message = "Now is the time for all good men "
        "to come to the aide of their country.";

    AES::Encryption aesEncryption(key, key.size());
    CTR_Mode_ExternalCipher::Encryption ctrEncryption(aesEncryption, iv);

    StreamTransformationFilter stfEncryptor(
        ctrEncryption, new StringSink(encrypted));

    stfEncryptor.Put((const byte*)&message[0], message.size());
    stfEncryptor.MessageEnd();

    AES::Encryption aesDecryption(key, key.size());
    CTR_Mode_ExternalCipher::Decryption ctrDecryption(aesDecryption, iv);

    StreamTransformationFilter stfDecryptor(
        ctrDecryption, new StringSink(decrypted));

    stfDecryptor.Put((const byte*)&encrypted[0], encrypted.size());
    stfDecryptor.MessageEnd();

    std::cout << "Message: " << message << std::endl;
    std::cout << "Recovered: " << decrypted << std::endl;

    return 0;
}

和:

$ g++ -g2 -O1 test.cxx ./libcryptopp.a -o test.exe
$ ./test.exe
Message: Now is the time for all good men to come to the aide of their country.
Recovered: Now is the time for all good men to come to the aide of their country.

对于计数器模式，不需要BlockPaddingSchemeDef::NO_PADDING。这是计数器模式的默认设置。

尽管不明显，但手册中 BlockPaddingScheme 的文档中对此进行了说明:

关于c++ - 使用Crypto++时AES/CTR解密意外停止了吗？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/59323973/