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Diffstat (limited to 'comm/third_party/botan/src/lib/rng/chacha_rng/chacha_rng.h')
| -rw-r--r-- | comm/third_party/botan/src/lib/rng/chacha_rng/chacha_rng.h | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/rng/chacha_rng/chacha_rng.h b/comm/third_party/botan/src/lib/rng/chacha_rng/chacha_rng.h new file mode 100644 index 0000000000..c50c2d0c25 --- /dev/null +++ b/comm/third_party/botan/src/lib/rng/chacha_rng/chacha_rng.h @@ -0,0 +1,125 @@ +/* +* ChaCha_RNG +* (C) 2017 Jack Lloyd +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#ifndef BOTAN_CHACHA_RNG_H_ +#define BOTAN_CHACHA_RNG_H_ + +#include <botan/stateful_rng.h> +#include <botan/stream_cipher.h> +#include <botan/mac.h> + +namespace Botan { + +class Entropy_Sources; + +/** +* ChaCha_RNG is a very fast but completely ad-hoc RNG created by +* creating a 256-bit random value and using it as a key for ChaCha20. +* +* The RNG maintains two 256-bit keys, one for HMAC_SHA256 (HK) and the +* other for ChaCha20 (CK). To compute a new key in response to +* reseeding request or add_entropy calls, ChaCha_RNG computes +* CK' = HMAC_SHA256(HK, input_material) +* Then a new HK' is computed by running ChaCha20 with the new key to +* output 32 bytes: +* HK' = ChaCha20(CK') +* +* Now output can be produced by continuing to produce output with ChaCha20 +* under CK' +* +* The first HK (before seeding occurs) is taken as the all zero value. +* +* @warning This RNG construction is probably fine but is non-standard. +* The primary reason to use it is in cases where the other RNGs are +* not fast enough. +*/ +class BOTAN_PUBLIC_API(2,3) ChaCha_RNG final : public Stateful_RNG + { + public: + /** + * Automatic reseeding is disabled completely, as it has no access to + * any source for seed material. + * + * If a fork is detected, the RNG will be unable to reseed itself + * in response. In this case, an exception will be thrown rather + * than generating duplicated output. + */ + ChaCha_RNG(); + + /** + * Provide an initial seed to the RNG, without providing an + * underlying RNG or entropy source. Automatic reseeding is + * disabled completely, as it has no access to any source for + * seed material. + * + * If a fork is detected, the RNG will be unable to reseed itself + * in response. In this case, an exception will be thrown rather + * than generating duplicated output. + * + * @param seed the seed material, should be at least 256 bits + */ + ChaCha_RNG(const secure_vector<uint8_t>& seed); + + /** + * Automatic reseeding from @p underlying_rng will take place after + * @p reseed_interval many requests or after a fork was detected. + * + * @param underlying_rng is a reference to some RNG which will be used + * to perform the periodic reseeding + * @param reseed_interval specifies a limit of how many times + * the RNG will be called before automatic reseeding is performed + */ + ChaCha_RNG(RandomNumberGenerator& underlying_rng, + size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL); + + /** + * Automatic reseeding from @p entropy_sources will take place after + * @p reseed_interval many requests or after a fork was detected. + * + * @param entropy_sources will be polled to perform reseeding periodically + * @param reseed_interval specifies a limit of how many times + * the RNG will be called before automatic reseeding is performed. + */ + ChaCha_RNG(Entropy_Sources& entropy_sources, + size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL); + + /** + * Automatic reseeding from @p underlying_rng and @p entropy_sources + * will take place after @p reseed_interval many requests or after + * a fork was detected. + * + * @param underlying_rng is a reference to some RNG which will be used + * to perform the periodic reseeding + * @param entropy_sources will be polled to perform reseeding periodically + * @param reseed_interval specifies a limit of how many times + * the RNG will be called before automatic reseeding is performed. + */ + ChaCha_RNG(RandomNumberGenerator& underlying_rng, + Entropy_Sources& entropy_sources, + size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL); + + std::string name() const override { return "ChaCha_RNG"; } + + size_t security_level() const override; + + size_t max_number_of_bytes_per_request() const override { return 0; } + + private: + void update(const uint8_t input[], size_t input_len) override; + + void generate_output(uint8_t output[], size_t output_len, + const uint8_t input[], size_t input_len) override; + + void clear_state() override; + + std::unique_ptr<MessageAuthenticationCode> m_hmac; + std::unique_ptr<StreamCipher> m_chacha; + }; + +} + +#endif |