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/*
* The MIT License
*
* Copyright (C) 2010-2016 Alexander Saprykin <saprykin.spb@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* 'Software'), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/**
* @file pcryptohash.h
* @brief Cryptographic hash function
* @author Alexander Saprykin
*
* A cryptographic hash function is an algorithm which performs a transformation
* of the income data to a hash value.
*
* One of the main requirements to all of the cryptographic hashing algorithms
* is that any (even a considerably small) change in the input data must lead to
* notable changes in the result hash value. It is the so called avalanche
* effect. It helps to avoid collisions (the same hash value for different
* input arrays).
*
* The cryptographic hash function is designed to be a one-way so you couldn't
* revert the output hash value to the input data back. The length of the
* resulting hash is a constant value depending on the algorithm being used.
*
* A cryptographic hash works with the incoming data using fixed length blocks
* so it is possible to feed as many data as required.
*
* The cryptographic hash module supports the following hash functions:
* - MD5;
* - SHA-1;
* - SHA-2/224;
* - SHA-2/256;
* - SHA-2/384;
* - SHA-2/512;
* - SHA-3/224;
* - SHA-3/256;
* - SHA-3/384;
* - SHA-3/512;
* - GOST (R 34.11-94).
*
* Use p_crypto_hash_new() to initialize a new hash context with one of the
* mentioned above types. Data for hashing can be added in several chunks using
* the p_crypto_hash_update() routine. You can add more chunks as long as the
* hash context is open.
*
* The hash context becomes close in two cases: p_crypto_hash_get_string() or
* p_crypto_hash_get_digest() was called. After that you can only get a hash in
* a hexidemical string or in a raw representation.
*
* A hashing algorithm couldn't be changed after the context initialization.
*/
#if !defined (PLIBSYS_H_INSIDE) && !defined (PLIBSYS_COMPILATION)
# error "Header files shouldn't be included directly, consider using <plibsys.h> instead."
#endif
#ifndef PLIBSYS_HEADER_PCRYPTOHASH_H
#define PLIBSYS_HEADER_PCRYPTOHASH_H
#include <pmacros.h>
#include <ptypes.h>
P_BEGIN_DECLS
/** Opaque data structure for handling a cryptographic hash context. */
typedef struct PCryptoHash_ PCryptoHash;
/** Cryptographic hash function types for #PCryptoHash. */
typedef enum PCryptoHashType_ {
P_CRYPTO_HASH_TYPE_MD5 = 0, /**< MD5 hash function. @since 0.0.1 */
P_CRYPTO_HASH_TYPE_SHA1 = 1, /**< SHA-1 hash function. @since 0.0.1 */
P_CRYPTO_HASH_TYPE_SHA2_224 = 2, /**< SHA-2/224 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_SHA2_256 = 3, /**< SHA-2/256 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_SHA2_384 = 4, /**< SHA-2/384 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_SHA2_512 = 5, /**< SHA-2/512 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_SHA3_224 = 6, /**< SHA-2/224 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_SHA3_256 = 7, /**< SHA-2/256 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_SHA3_384 = 8, /**< SHA-2/384 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_SHA3_512 = 9, /**< SHA-3/512 hash function. @since 0.0.2 */
P_CRYPTO_HASH_TYPE_GOST = 10 /**< GOST (R 34.11-94) hash function. @since 0.0.1 */
} PCryptoHashType;
/**
* @brief Initializes a new #PCryptoHash context.
* @param type Hash function type to use, can't be changed later.
* @return Newly initialized #PCryptoHash context in case of success, NULL
* otherwise.
* @since 0.0.1
*/
P_LIB_API PCryptoHash * p_crypto_hash_new (PCryptoHashType type);
/**
* @brief Adds a new chunk of data for hashing.
* @param hash #PCryptoHash context to add @a data to.
* @param data Data to add for hashing.
* @param len Data length, in bytes.
* @note After calling p_crypto_hash_get_string() or p_crypto_hash_get_digest()
* the hash couldn't be updated anymore as it becomes close.
* @since 0.0.1
*/
P_LIB_API void p_crypto_hash_update (PCryptoHash *hash,
const puchar *data,
psize len);
/**
* @brief Resets a hash state.
* @param hash #PCryptoHash context to reset.
* @since 0.0.1
*
* After a reset the hash context becomes open for updating, but all previously
* added data will be lost. A hash function type couldn't be changed during or
* after the resets.
*/
P_LIB_API void p_crypto_hash_reset (PCryptoHash *hash);
/**
* @brief Gets a hash in a hexidemical representation.
* @param hash #PCryptoHash context to get a string from.
* @return NULL-terminated string with the hexidemical representation of a hash
* state in case of success, NULL otherwise. The string should be freed with
* p_free() after using it.
* @note Before returning the string the hash context will be closed for further
* updates.
* @since 0.0.1
*/
P_LIB_API pchar * p_crypto_hash_get_string (PCryptoHash *hash);
/**
* @brief Gets a hash in a raw representation.
* @param hash #PCryptoHash context to get a digest from.
* @param buf Buffer to store the digest with the hash raw representation.
* @param[in,out] len Size of @a buf when calling, count of written bytes
* after.
* @note Before getting the raw digest the hash context will be closed for
* further updates.
* @since 0.0.1
*/
P_LIB_API void p_crypto_hash_get_digest (PCryptoHash *hash,
puchar *buf,
psize *len);
/**
* @brief Gets a hash digest length depending on its type.
* @param hash #PCryptoHash context to get the length for.
* @return Length (in bytes) of the given hash depending on its type in case of
* success, -1 otherwise.
* @note This length doesn't match a string hash representation.
* @since 0.0.1
*/
P_LIB_API pssize p_crypto_hash_get_length (const PCryptoHash *hash);
/**
* @brief Gets a hash function type.
* @param hash #PCryptoHash context to get the type for.
* @return Hash function type used in the given context.
* @since 0.0.1
*/
P_LIB_API PCryptoHashType p_crypto_hash_get_type (const PCryptoHash *hash);
/**
* @brief Frees a previously initialized hash context.
* @param hash #PCryptoHash context to free.
* @since 0.0.1
*/
P_LIB_API void p_crypto_hash_free (PCryptoHash *hash);
P_END_DECLS
#endif /* PLIBSYS_HEADER_PCRYPTOHASH_H */
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