/* * CFB mode * (C) 1999-2007,2013 Jack Lloyd * (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity * * Botan is released under the Simplified BSD License (see license.txt) */ #ifndef BOTAN_MODE_CFB_H__ #define BOTAN_MODE_CFB_H__ #include #include namespace Botan { /** * CFB Mode */ class BOTAN_PUBLIC_API(2,0) CFB_Mode : public Cipher_Mode { public: std::string name() const override; size_t update_granularity() const override; size_t minimum_final_size() const override; Key_Length_Specification key_spec() const override; size_t output_length(size_t input_length) const override; size_t default_nonce_length() const override; bool valid_nonce_length(size_t n) const override; void clear() override; void reset() override; protected: CFB_Mode(BlockCipher* cipher, size_t feedback_bits); size_t feedback() const { return m_feedback_bytes; } const BlockCipher& cipher() const { return *m_cipher; } secure_vector m_state; secure_vector m_keystream; size_t m_keystream_pos = 0; private: void start_msg(const uint8_t nonce[], size_t nonce_len) override; void key_schedule(const uint8_t key[], size_t length) override; std::unique_ptr m_cipher; const size_t m_feedback_bytes; }; /** * CFB Encryption */ class BOTAN_PUBLIC_API(2,0) CFB_Encryption final : public CFB_Mode { public: /** * If feedback_bits is zero, cipher->block_size() bytes will be used. * @param cipher block cipher to use * @param feedback_bits number of bits fed back into the shift register, * must be a multiple of 8 */ CFB_Encryption(BlockCipher* cipher, size_t feedback_bits) : CFB_Mode(cipher, feedback_bits) {} size_t process(uint8_t buf[], size_t size) override; void finish(secure_vector& final_block, size_t offset = 0) override; }; /** * CFB Decryption */ class BOTAN_PUBLIC_API(2,0) CFB_Decryption final : public CFB_Mode { public: /** * If feedback_bits is zero, cipher->block_size() bytes will be used. * @param cipher block cipher to use * @param feedback_bits number of bits fed back into the shift register, * must be a multiple of 8 */ CFB_Decryption(BlockCipher* cipher, size_t feedback_bits) : CFB_Mode(cipher, feedback_bits) {} size_t process(uint8_t buf[], size_t size) override; void finish(secure_vector& final_block, size_t offset = 0) override; }; } #endif