| // Copyright 2016 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COBALT_SRC_LIB_CRYPTO_UTIL_RANDOM_TEST_UTILS_H_ |
| #define COBALT_SRC_LIB_CRYPTO_UTIL_RANDOM_TEST_UTILS_H_ |
| |
| #include <openssl/chacha.h> |
| |
| #include "src/lib/crypto_util/random.h" |
| |
| namespace cobalt { |
| namespace crypto { |
| |
| // DeterministicRandom is a subclass of Random that overrides RandomBytes() |
| // to use a deterministic PRNG. |
| class DeterministicRandom : public Random { |
| public: |
| DeterministicRandom() = default; |
| |
| ~DeterministicRandom() override = default; |
| |
| // Implementes a deterministic PRNG by using chacha20 with a zero key and a |
| // counter for the nonce. This code was copied from |
| // crypto/rand/deteriministic.c in Boring SSL. We use this particular |
| // PRNG becuase it has some properties in common with the non-deterministic |
| // version of RandomBytes we use in production and so we are testing using |
| // a source of randomness that is similar to the production source of |
| // randomness. |
| void RandomBytes(byte *buf, std::size_t num) override { |
| static const uint8_t kZeroKey[32] = {}; |
| uint8_t nonce[12]; // NOLINT readability-magic-numbers |
| memset(nonce, 0, sizeof(nonce)); |
| memcpy(nonce, &num_calls_, sizeof(num_calls_)); |
| |
| memset(buf, 0, num); |
| CRYPTO_chacha_20(buf, buf, num, kZeroKey, nonce, 0); |
| num_calls_++; |
| } |
| |
| private: |
| uint64_t num_calls_ = 0; |
| }; |
| |
| } // namespace crypto |
| } // namespace cobalt |
| |
| #endif // COBALT_SRC_LIB_CRYPTO_UTIL_RANDOM_TEST_UTILS_H_ |