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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @file parc_SecureRandom.h
* @brief A cryptographically secure pseudorandom number generator that reads
* from a secure randomness source on the system, e.g., /dev/urandom.
*
*/
#ifndef Libparc_parc_SecureRandom
#define Libparc_parc_SecureRandom
#include <stdbool.h>
#include <parc/algol/parc_Object.h>
struct parc_securerandom;
typedef struct parc_securerandom PARCSecureRandom;
/**
* Increase the number of references to a `PARCSecureRandom` instance.
*
* Note that new `PARCSecureRandom` is not created,
* only that the given `PARCSecureRandom` reference count is incremented.
* Discard the reference by invoking `parcSecureRandom_Release`.
*
* @param [in] instance A pointer to a valid PARCSecureRandom instance.
*
* @return The same value as @p instance.
*
* Example:
* @code
* {
* PARCSecureRandom *a = parcSecureRandom_Create();
*
* PARCSecureRandom *b = parcSecureRandom_Acquire();
*
* parcSecureRandom_Release(&a);
* parcSecureRandom_Release(&b);
* }
* @endcode
*/
PARCSecureRandom *parcSecureRandom_Acquire(const PARCSecureRandom *instance);
/**
* Create an instance of PARCSecureRandom
*
* @return non-NULL A pointer to a valid PARCSecureRandom instance.
* @return NULL An error occurred.
*
* Example:
* @code
* {
* PARCSecureRandom *rng = parcSecureRandom_Create();
*
* parcSecureRandom_Release(&rng);
* }
* @endcode
*/
PARCSecureRandom *parcSecureRandom_Create(void);
/**
* Create an instance of PARCSecureRandom with a specific seed stored in
* a `PARCBuffer` instance.
*
* @param [in] seed A `PARCBuffer` instance.
*
* @return non-NULL A pointer to a valid PARCSecureRandom instance.
* @return NULL An error occurred.
*
* Example:
* @code
* {
* PARCBuffer *seed = ...
* PARCSecureRandom *rng = parcSecureRandom_CreateWithSeed(seed);
*
* parcSecureRandom_Release(&rng);
* }
* @endcode
*/
PARCSecureRandom *parcSecureRandom_CreateWithSeed(PARCBuffer *seed);
/**
* Generate a 32-bit unsigned integer from a `PARCSecureRandom` instance.
*
* @param [in] rng A `PARCSecureRandom` instance.
*
* @return non-NULL A pointer to a valid PARCSecureRandom instance.
* @return NULL An error occurred.
*
* Example:
* @code
* {
* PARCSecureRandom *rng = parcSecureRandom_Create();
*
* uint32_t nextWord = parcSecureRandom_Next(rng);
* // use the word
* }
* @endcode
*/
uint32_t parcSecureRandom_Next(PARCSecureRandom *rng);
/**
* Fill a `PARCBuffer` instance with random bytes from a `PARCSecureRandom` instance.
* The resultant `PARCBuffer` will be ready for reading, i.e., one does not need
* to call `parcBuffer_Flip()` on the result.
*
* @param [in] rng A `PARCSecureRandom` instance.
* @param [in] buffer A `PARCBuffer` instance to fill.
*
* @return non-NULL A pointer to a valid PARCSecureRandom instance.
* @return NULL An error occurred.
*
* Example:
* @code
* {
* PARCSecureRandom *rng = parcSecureRandom_Create();
*
* PARCBuffer *buffer = parcBuffer_Allocate(32);
* ssize_t numBytes = parcSecureRandom_NextBytes(rng, buffer);
* // use the buffer
* }
* @endcode
*/
ssize_t parcSecureRandom_NextBytes(PARCSecureRandom *rng, PARCBuffer *buffer);
/**
* Determine if an instance of `PARCSecureRandom` is valid.
*
* Valid means the internal state of the type is consistent with its required current or future behaviour.
* This may include the validation of internal instances of types.
*
* @param [in] instance A pointer to a valid PARCSecureRandom instance.
*
* @return true The instance is valid.
* @return false The instance is not valid.
*
* Example:
* @code
* {
* PARCSecureRandom *rng = parcSecureRandom_Create();
*
* if (parcSecureRandom_IsValid(rng)) {
* printf("Instance is valid.\n");
* }
*
* parcSecureRandom_Release(&rng);
* }
* @endcode
*
*/
bool parcSecureRandom_IsValid(const PARCSecureRandom *instance);
/**
* Release a previously acquired reference to the given `PARCSecureRandom` instance,
* decrementing the reference count for the instance.
*
* The pointer to the instance is set to NULL as a side-effect of this function.
*
* If the invocation causes the last reference to the instance to be released,
* the instance is deallocated and the instance's implementation will perform
* additional cleanup and release other privately held references.
*
* @param [in,out] instancePtr A pointer to a pointer to the instance to release.
*
* Example:
* @code
* {
* PARCSecureRandom *rng = parcSecureRandom_Create();
*
* parcSecureRandom_Release(&rng);
* }
* @endcode
*/
void parcSecureRandom_Release(PARCSecureRandom **instancePtr);
#endif
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