Botan
1.11.15
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00001 /* 00002 * OCB Mode 00003 * (C) 2013,2014 Jack Lloyd 00004 * 00005 * Botan is released under the Simplified BSD License (see license.txt) 00006 */ 00007 00008 #ifndef BOTAN_AEAD_OCB_H__ 00009 #define BOTAN_AEAD_OCB_H__ 00010 00011 #include <botan/aead.h> 00012 #include <botan/block_cipher.h> 00013 00014 namespace Botan { 00015 00016 class L_computer; 00017 00018 /** 00019 * OCB Mode (base class for OCB_Encryption and OCB_Decryption). Note 00020 * that OCB is patented, but is freely licensed in some circumstances. 00021 * 00022 * @see "The OCB Authenticated-Encryption Algorithm" internet draft 00023 http://tools.ietf.org/html/draft-irtf-cfrg-ocb-03 00024 * @see Free Licenses http://www.cs.ucdavis.edu/~rogaway/ocb/license.htm 00025 * @see OCB home page http://www.cs.ucdavis.edu/~rogaway/ocb 00026 */ 00027 class BOTAN_DLL OCB_Mode : public AEAD_Mode 00028 { 00029 public: 00030 void set_associated_data(const byte ad[], size_t ad_len) override; 00031 00032 std::string name() const override; 00033 00034 size_t update_granularity() const override; 00035 00036 Key_Length_Specification key_spec() const override; 00037 00038 bool valid_nonce_length(size_t) const override; 00039 00040 size_t tag_size() const override { return m_tag_size; } 00041 00042 void clear() override; 00043 00044 ~OCB_Mode(); 00045 protected: 00046 /** 00047 * @param cipher the 128-bit block cipher to use 00048 * @param tag_size is how big the auth tag will be 00049 */ 00050 OCB_Mode(BlockCipher* cipher, size_t tag_size); 00051 00052 size_t BS() const { return m_BS; } 00053 00054 // fixme make these private 00055 std::unique_ptr<BlockCipher> m_cipher; 00056 std::unique_ptr<L_computer> m_L; 00057 00058 size_t m_BS; 00059 size_t m_block_index = 0; 00060 00061 secure_vector<byte> m_checksum; 00062 secure_vector<byte> m_offset; 00063 secure_vector<byte> m_ad_hash; 00064 private: 00065 secure_vector<byte> start_raw(const byte nonce[], size_t nonce_len) override; 00066 00067 void key_schedule(const byte key[], size_t length) override; 00068 00069 secure_vector<byte> update_nonce(const byte nonce[], size_t nonce_len); 00070 00071 size_t m_tag_size = 0; 00072 secure_vector<byte> m_last_nonce; 00073 secure_vector<byte> m_stretch; 00074 }; 00075 00076 class BOTAN_DLL OCB_Encryption : public OCB_Mode 00077 { 00078 public: 00079 /** 00080 * @param cipher the 128-bit block cipher to use 00081 * @param tag_size is how big the auth tag will be 00082 */ 00083 OCB_Encryption(BlockCipher* cipher, size_t tag_size = 16) : 00084 OCB_Mode(cipher, tag_size) {} 00085 00086 size_t output_length(size_t input_length) const override 00087 { return input_length + tag_size(); } 00088 00089 size_t minimum_final_size() const override { return 0; } 00090 00091 void update(secure_vector<byte>& blocks, size_t offset = 0) override; 00092 00093 void finish(secure_vector<byte>& final_block, size_t offset = 0) override; 00094 private: 00095 void encrypt(byte input[], size_t blocks); 00096 }; 00097 00098 class BOTAN_DLL OCB_Decryption : public OCB_Mode 00099 { 00100 public: 00101 /** 00102 * @param cipher the 128-bit block cipher to use 00103 * @param tag_size is how big the auth tag will be 00104 */ 00105 OCB_Decryption(BlockCipher* cipher, size_t tag_size = 16) : 00106 OCB_Mode(cipher, tag_size) {} 00107 00108 size_t output_length(size_t input_length) const override 00109 { 00110 BOTAN_ASSERT(input_length > tag_size(), "Sufficient input"); 00111 return input_length - tag_size(); 00112 } 00113 00114 size_t minimum_final_size() const override { return tag_size(); } 00115 00116 void update(secure_vector<byte>& blocks, size_t offset = 0) override; 00117 00118 void finish(secure_vector<byte>& final_block, size_t offset = 0) override; 00119 private: 00120 void decrypt(byte input[], size_t blocks); 00121 }; 00122 00123 } 00124 00125 #endif