Botan  1.11.15
src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h
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00001 /*
00002 * ChaCha20Poly1305 AEAD
00003 * (C) 2014 Jack Lloyd
00004 *
00005 * Botan is released under the Simplified BSD License (see license.txt)
00006 */
00007 
00008 #ifndef BOTAN_AEAD_CHACHA20_POLY1305_H__
00009 #define BOTAN_AEAD_CHACHA20_POLY1305_H__
00010 
00011 #include <botan/aead.h>
00012 #include <botan/stream_cipher.h>
00013 #include <botan/mac.h>
00014 
00015 namespace Botan {
00016 
00017 /**
00018 * Base class
00019 * See draft-irtf-cfrg-chacha20-poly1305-03 for specification
00020 * If a nonce of 64 bits is used the older version described in
00021 * draft-agl-tls-chacha20poly1305-04 is used instead.
00022 */
00023 class BOTAN_DLL ChaCha20Poly1305_Mode : public AEAD_Mode
00024    {
00025    public:
00026       void set_associated_data(const byte ad[], size_t ad_len) override;
00027 
00028       std::string name() const override { return "ChaCha20Poly1305"; }
00029 
00030       size_t update_granularity() const override { return 64; }
00031 
00032       Key_Length_Specification key_spec() const override
00033          { return Key_Length_Specification(32); }
00034 
00035       bool valid_nonce_length(size_t n) const override;
00036 
00037       size_t tag_size() const override { return 16; }
00038 
00039       void clear() override;
00040    protected:
00041       std::unique_ptr<StreamCipher> m_chacha;
00042       std::unique_ptr<MessageAuthenticationCode> m_poly1305;
00043 
00044       secure_vector<byte> m_ad;
00045       size_t m_nonce_len = 0;
00046       size_t m_ctext_len = 0;
00047 
00048       bool cfrg_version() const { return m_nonce_len == 12; }
00049       void update_len(size_t len);
00050    private:
00051       secure_vector<byte> start_raw(const byte nonce[], size_t nonce_len) override;
00052 
00053       void key_schedule(const byte key[], size_t length) override;
00054    };
00055 
00056 /**
00057 * ChaCha20Poly1305 Encryption
00058 */
00059 class BOTAN_DLL ChaCha20Poly1305_Encryption : public ChaCha20Poly1305_Mode
00060    {
00061    public:
00062       size_t output_length(size_t input_length) const override
00063          { return input_length + tag_size(); }
00064 
00065       size_t minimum_final_size() const override { return 0; }
00066 
00067       void update(secure_vector<byte>& blocks, size_t offset = 0) override;
00068 
00069       void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
00070    };
00071 
00072 /**
00073 * ChaCha20Poly1305 Decryption
00074 */
00075 class BOTAN_DLL ChaCha20Poly1305_Decryption : public ChaCha20Poly1305_Mode
00076    {
00077    public:
00078       size_t output_length(size_t input_length) const override
00079          {
00080          BOTAN_ASSERT(input_length > tag_size(), "Sufficient input");
00081          return input_length - tag_size();
00082          }
00083 
00084       size_t minimum_final_size() const override { return tag_size(); }
00085 
00086       void update(secure_vector<byte>& blocks, size_t offset = 0) override;
00087 
00088       void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
00089    };
00090 
00091 }
00092 
00093 #endif