Botan  2.12.1
Crypto and TLS for C++11
chacha.h
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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 
14 
15 namespace Botan {
16 
17 /**
18 * DJB's ChaCha (https://cr.yp.to/chacha.html)
19 */
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;
76  secure_vector<uint8_t> m_buffer;
77  size_t m_position = 0;
78  };
79 
80 }
81 
82 #endif
virtual size_t default_iv_length() const
int(* final)(unsigned char *, CTX *)
#define BOTAN_PUBLIC_API(maj, min)
Definition: compiler.h:31
virtual void cipher(const uint8_t in[], uint8_t out[], size_t len)=0
virtual bool valid_iv_length(size_t iv_len) const
virtual std::string name() const =0
virtual std::string provider() const
virtual void write_keystream(uint8_t out[], size_t len)
Definition: stream_cipher.h:66
virtual void clear()=0
virtual void seek(uint64_t offset)=0
Definition: alg_id.cpp:13
virtual Key_Length_Specification key_spec() const =0
virtual StreamCipher * clone() const =0
std::vector< T, secure_allocator< T > > secure_vector
Definition: secmem.h:65
virtual void set_iv(const uint8_t iv[], size_t iv_len)=0
#define BOTAN_FUTURE_INTERNAL_HEADER(hdr)
Definition: compiler.h:139