text: // Copyright 2016 PDFium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
  
  #ifndef CORE_FPDFAPI_PARSER_CPDF_CRYPTO_HANDLER_H_
  #define CORE_FPDFAPI_PARSER_CPDF_CRYPTO_HANDLER_H_
  
  #include <stddef.h>
  #include <stdint.h>
  
  #include <memory>
  
  #include "core/fdrm/fx_crypt.h"
  #include "core/fxcrt/bytestring.h"
  #include "core/fxcrt/cfx_binarybuf.h"
  #include "core/fxcrt/fx_memory_wrappers.h"
  #include "core/fxcrt/retain_ptr.h"
  #include "third_party/base/span.h"
  
  class CPDF_Dictionary;
  class CPDF_Object;
  
  class CPDF_CryptoHandler {
   public:
    enum class Cipher {
      kNone = 0,
      kRC4 = 1,
      kAES = 2,
      kAES2 = 3,
    };
  
    static bool IsSignatureDictionary(const CPDF_Dictionary* dictionary);
  
    CPDF_CryptoHandler(Cipher cipher, const uint8_t* key, size_t keylen);
    ~CPDF_CryptoHandler();
  
    bool DecryptObjectTree(RetainPtr<CPDF_Object> object);
    size_t EncryptGetSize(pdfium::span<const uint8_t> source) const;
    void EncryptContent(uint32_t objnum,
                        uint32_t gennum,
                        pdfium::span<const uint8_t> source,
                        uint8_t* dest_buf,
                        size_t& dest_size) const;
  
    bool IsCipherAES() const;
  
   private:
    size_t DecryptGetSize(size_t src_size);
    void* DecryptStart(uint32_t objnum, uint32_t gennum);
    ByteString Decrypt(uint32_t objnum, uint32_t gennum, const ByteString& str);
    bool DecryptStream(void* context,
                       pdfium::span<const uint8_t> source,
                       CFX_BinaryBuf& dest_buf);
    bool DecryptFinish(void* context, CFX_BinaryBuf& dest_buf);
    void PopulateKey(uint32_t objnum, uint32_t gennum, uint8_t* key) const;
  
    const size_t m_KeyLen;
    const Cipher m_Cipher;
    std::unique_ptr<CRYPT_aes_context, FxFreeDeleter> m_pAESContext;
    uint8_t m_EncryptKey[32];
  };
  
  #endif  // CORE_FPDFAPI_PARSER_CPDF_CRYPTO_HANDLER_H_
  