InvalidCiphertext exception

您的主要问题似乎是使用getline和Decryption()中的''分隔符。如果Encryption()中的纯文本不包含空字符，这可能适用于该文本，但密文很可能始终充满''。

看起来好像您已经正确地识别出加密文件包含二进制数据，但您需要按原样读取它，例如使用std::ifstream::read或std::istreambuf_iterator。

我已经更新了你的示例代码如下：

#include "windows.h"
#include <algorithm>  // for std::copy
#include <fstream>
#include <iostream>
#include <iterator>  // for std::istreambuf_iterator
#include <string>
#ifdef _MSC_VER
#  pragma warning(push)
#  pragma warning(disable: 4100 4127 4189 4244)
#endif
#include "cryptopp/aes.h"
#include "cryptopp/config.h"
#include "cryptopp/files.h"
#include "cryptopp/filters.h"
#include "cryptopp/modes.h"
#ifdef _MSC_VER
#  pragma warning(pop)
#endif
namespace {
const std::string original_file("original.txt");
const std::string encrypted_file("encrypted.txt");
const std::string decrypted_file("decrypted.txt");
const int key_size(CryptoPP::AES::DEFAULT_KEYLENGTH);
const int iv_size(CryptoPP::AES::BLOCKSIZE);
}
void GetKeyAndIv(byte* key, byte* iv) {
  HW_PROFILE_INFOA profile;
  GetCurrentHwProfileA(&profile);
  char* guid(profile.szHwProfileGuid);
  assert(std::char_traits<char>::length(guid) >= key_size + iv_size);
  // Assign first 'key_size' chars of GUID to 'key'
  std::copy(guid, guid + key_size, key);
  // Assign next 'iv_size' chars of GUID to 'iv'
  std::copy(guid + key_size, guid + key_size + iv_size, iv);
};
void Encrypt() {
  // Initialise the key and IV
  byte key[key_size] = {0}, iv[iv_size] = {0};
  GetKeyAndIv(key, iv);
  // Read the file contents to a string and output to cout.  Safest to read
  // contents as binary data, although non-printable characters shouldn't be
  // output to cout.
  std::ifstream infile(original_file.c_str(), std::ios::binary);
  const std::string plaintext((std::istreambuf_iterator<char>(infile)),
                               std::istreambuf_iterator<char>());
  infile.close();
  std::cout << "Plain Text (" << plaintext.size() << " bytes)n"
            << plaintext << "nn";
  // Encrypt
  CryptoPP::AES::Encryption cipher(key, key_size);
  CryptoPP::CBC_Mode_ExternalCipher::Encryption encryption(cipher, iv);
  std::string cipher_text;
  CryptoPP::StreamTransformationFilter filter(encryption,
      new CryptoPP::StringSink(cipher_text));
  filter.Put(reinterpret_cast<const byte*>(plaintext.c_str()), plaintext.size());
  filter.MessageEnd();
  // Dump cipher text
  std::ofstream outfile(encrypted_file.c_str(), std::ios::binary);
  outfile.write(cipher_text.c_str(), cipher_text.size());
  outfile.close();
}
void Decrypt() {
  // Initialise the key and IV
  byte key[key_size] = {0}, iv[iv_size] = {0};
  GetKeyAndIv(key, iv);
  // Read the encrypted file contents to a string as binary data.
  std::ifstream infile(encrypted_file.c_str(), std::ios::binary);
  const std::string cipher_text((std::istreambuf_iterator<char>(infile)),
                                 std::istreambuf_iterator<char>());
  infile.close();
  // Decrypt
  CryptoPP::AES::Decryption cipher(key, key_size);
  CryptoPP::CBC_Mode_ExternalCipher::Decryption decryption(cipher, iv);
  std::string decrypted_test;
  CryptoPP::StreamTransformationFilter filter(decryption,
      new CryptoPP::StringSink(decrypted_test));
  filter.Put(reinterpret_cast<const byte*>(cipher_text.c_str()),
             cipher_text.size());
  filter.MessageEnd();
  // Dump decrypted text
  std::ofstream outfile(decrypted_file.c_str(), std::ios::binary);
  outfile.write(decrypted_test.c_str(), decrypted_test.size());
  outfile.close();
}
int main() {
  try {
    Encrypt();
    Decrypt();
  }
  catch(const CryptoPP::Exception& exception) {
    std::cout << "Caught exception: " << exception.what() << 'n';
    return -1;
  }
  return 0;
}

一个更直接的选择是使用CryptoPP的FileSource和FileSink类来避免手动读取/写入文件：

void Encrypt() {
  byte key[key_size] = {0}, iv[iv_size] = {0};
  GetKeyAndIv(key, iv);
  CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption encryption;
  encryption.SetKeyWithIV(key, key_size, iv, iv_size);
  CryptoPP::FileSource file_source(original_file.c_str(), true,
    new CryptoPP::StreamTransformationFilter(encryption,
      new CryptoPP::FileSink(encrypted_file.c_str())));
}
void Decrypt() {
  byte key[key_size] = {0}, iv[iv_size] = {0};
  GetKeyAndIv(key, iv);
  CryptoPP::CBC_Mode<CryptoPP::AES>::Decryption decryption;
  decryption.SetKeyWithIV(key, key_size, iv, iv_size);
  CryptoPP::FileSource file_source(encrypted_file.c_str(), true,
    new CryptoPP::StreamTransformationFilter(decryption,
      new CryptoPP::FileSink(decrypted_file.c_str())));
}