Botan 2.19.5 Crypto and TLS for C&

chacha_rng.cpp
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1/*
2* ChaCha_RNG
3* (C) 2017 Jack Lloyd
4*
5* Botan is released under the Simplified BSD License (see license.txt)
6*/
7
8#include <botan/chacha_rng.h>
9
10 namespace Botan {
11
12 ChaCha_RNG::ChaCha_RNG() : Stateful_RNG()
13 {
14 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
15 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
16 clear();
17 }
18
19 ChaCha_RNG::ChaCha_RNG(const secure_vector<uint8_t>& seed) : Stateful_RNG()
20 {
21 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
22 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
23 clear();
24 add_entropy(seed.data(), seed.size());
25 }
26
27 ChaCha_RNG::ChaCha_RNG(RandomNumberGenerator& underlying_rng,
28 size_t reseed_interval) :
29 Stateful_RNG(underlying_rng, reseed_interval)
30 {
31 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
32 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
33 clear();
34 }
35
36 ChaCha_RNG::ChaCha_RNG(RandomNumberGenerator& underlying_rng,
37 Entropy_Sources& entropy_sources,
38 size_t reseed_interval) :
39 Stateful_RNG(underlying_rng, entropy_sources, reseed_interval)
40 {
41 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
42 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
43 clear();
44 }
45
46 ChaCha_RNG::ChaCha_RNG(Entropy_Sources& entropy_sources,
47 size_t reseed_interval) :
48 Stateful_RNG(entropy_sources, reseed_interval)
49 {
50 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
51 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
52 clear();
53 }
54
55 void ChaCha_RNG::clear_state()
56 {
57 m_hmac->set_key(std::vector<uint8_t>(m_hmac->output_length(), 0x00));
58 m_chacha->set_key(m_hmac->final());
59 }
60
61 void ChaCha_RNG::generate_output(uint8_t output[], size_t output_len,
62 const uint8_t input[], size_t input_len)
63 {
64 if(input_len > 0)
65 {
66 update(input, input_len);
67 }
68
69 m_chacha->write_keystream(output, output_len);
70 }
71
72 void ChaCha_RNG::update(const uint8_t input[], size_t input_len)
73 {
74 m_hmac->update(input, input_len);
75 m_chacha->set_key(m_hmac->final());
76
77 secure_vector<uint8_t> mac_key(m_hmac->output_length());
78 m_chacha->write_keystream(mac_key.data(), mac_key.size());
79 m_hmac->set_key(mac_key);
80 }
81
82 size_t ChaCha_RNG::security_level() const
83 {
84 return 256;
85 }
86
87}
Botan::ChaCha_RNG::security_level
size_t security_level() const override
Definition: chacha_rng.cpp:82
Botan::ChaCha_RNG::ChaCha_RNG
ChaCha_RNG()
Definition: chacha_rng.cpp:12
Botan::Entropy_Sources
Definition: entropy_src.h:57
Botan::MessageAuthenticationCode::create_or_throw
static std::unique_ptr< MessageAuthenticationCode > create_or_throw(const std::string &algo_spec, const std::string &provider="")
Definition: mac.cpp:139
Botan::RandomNumberGenerator
Definition: rng.h:26
Botan::Stateful_RNG
Definition: stateful_rng.h:27
Botan::Stateful_RNG::clear
void clear() override final
Definition: stateful_rng.cpp:17
Botan::Stateful_RNG::add_entropy
void add_entropy(const uint8_t input[], size_t input_len) override final
Definition: stateful_rng.cpp:37
Botan::StreamCipher::create_or_throw
static std::unique_ptr< StreamCipher > create_or_throw(const std::string &algo_spec, const std::string &provider="")
Definition: stream_cipher.cpp:123
Botan
Definition: alg_id.cpp:13
Botan::secure_vector
std::vector< T, secure_allocator< T > > secure_vector
Definition: secmem.h:65