Botan  2.4.0
Crypto and TLS for C++11
chacha.h
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1 /*
2 * ChaCha20
3 * (C) 2014 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 namespace Botan {
14 
15 /**
16 * DJB's ChaCha (https://cr.yp.to/chacha.html)
17 */
18 class BOTAN_PUBLIC_API(2,0) ChaCha final : public StreamCipher
19  {
20  public:
21  StreamCipher* clone() const override { return new ChaCha(m_rounds); }
22 
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 set_iv(const uint8_t iv[], size_t iv_len) override;
35 
36  /*
37  * ChaCha accepts 0, 8, or 12 byte IVs. The default IV is a 8 zero bytes.
38  * An IV of length 0 is treated the same as the default zero IV.
39  */
40  bool valid_iv_length(size_t iv_len) const override;
41 
43  {
44  return Key_Length_Specification(16, 32, 16);
45  }
46 
47  void clear() override;
48 
49  std::string name() const override;
50 
51  void seek(uint64_t offset) override;
52 
53  private:
54  void key_schedule(const uint8_t key[], size_t key_len) override;
55 
56  void chacha_x4(uint8_t output[64*4], uint32_t state[16], size_t rounds);
57 
58 #if defined(BOTAN_HAS_CHACHA_SSE2)
59  void chacha_sse2_x4(uint8_t output[64*4], uint32_t state[16], size_t rounds);
60 #endif
61 
62  size_t m_rounds;
64  secure_vector<uint8_t> m_buffer;
65  size_t m_position = 0;
66  };
67 
68 }
69 
70 #endif
#define BOTAN_PUBLIC_API(maj, min)
Definition: compiler.h:27
StreamCipher * clone() const override
Definition: chacha.h:21
Definition: alg_id.cpp:13
std::vector< T, secure_allocator< T > > secure_vector
Definition: secmem.h:88
Key_Length_Specification key_spec() const override
Definition: chacha.h:42