1 /* 2 * ChaCha20 3 * (C) 2014,2018 Jack Lloyd 4 * 5 * Botan is released under the Simplified BSD License (see license.txt) 6 */ 7 8 #ifndef BOTAN_CHACHA_H_ 9 #define BOTAN_CHACHA_H_ 10 11 #include <botan/stream_cipher.h> 12 13 BOTAN_FUTURE_INTERNAL_HEADER(chacha.h) 14 15 namespace Botan { 16 17 /** 18 * DJB's ChaCha (https://cr.yp.to/chacha.html) 19 */ 20 class BOTAN_PUBLIC_API(2,0) ChaCha final : public StreamCipher 21 { 22 public: 23 /** 24 * @param rounds number of rounds 25 * @note Currently only 8, 12 or 20 rounds are supported, all others 26 * will throw an exception 27 */ 28 explicit ChaCha(size_t rounds = 20); 29 30 std::string provider() const override; 31 32 void cipher(const uint8_t in[], uint8_t out[], size_t length) override; 33 34 void write_keystream(uint8_t out[], size_t len) override; 35 36 void set_iv(const uint8_t iv[], size_t iv_len) override; 37 38 /* 39 * ChaCha accepts 0, 8, 12 or 24 byte IVs. 40 * The default IV is a 8 zero bytes. 41 * An IV of length 0 is treated the same as the default zero IV. 42 * An IV of length 24 selects XChaCha mode 43 */ 44 bool valid_iv_length(size_t iv_len) const override; 45 46 size_t default_iv_length() const override; 47 48 Key_Length_Specification key_spec() const override; 49 50 void clear() override; 51 52 StreamCipher* clone() const override; 53 54 std::string name() const override; 55 56 void seek(uint64_t offset) override; 57 58 private: 59 void key_schedule(const uint8_t key[], size_t key_len) override; 60 61 void initialize_state(); 62 63 void chacha_x8(uint8_t output[64*8], uint32_t state[16], size_t rounds); 64 65 #if defined(BOTAN_HAS_CHACHA_SIMD32) 66 void chacha_simd32_x4(uint8_t output[64*4], uint32_t state[16], size_t rounds); 67 #endif 68 69 #if defined(BOTAN_HAS_CHACHA_AVX2) 70 void chacha_avx2_x8(uint8_t output[64*8], uint32_t state[16], size_t rounds); 71 #endif 72 73 size_t m_rounds; 74 secure_vector<uint32_t> m_key; 75 secure_vector<uint32_t> m_state; 76 secure_vector<uint8_t> m_buffer; 77 size_t m_position = 0; 78 }; 79 80 } 81 82 #endif 83