/**
 * \file sha2.h
 */




/*
 * FIPS-180-2 compliant SHA-256 implementation
 *
 * Copyright (C) Brainspark B.V.
 *
 * IUPAC/InChI-Trust Licence No.1.0 for the 
 * International Chemical Identifier (InChI) Software version 1.04
 * Copyright (C) IUPAC and InChI Trust Limited
 * 
 * This library is free software; you can redistribute it and/or modify it 
 * under the terms of the IUPAC/InChI Trust InChI Licence No.1.0, 
 * or any later version.
 * 
 * Please note that this library is distributed WITHOUT ANY WARRANTIES 
 * whatsoever, whether expressed or implied.  See the IUPAC/InChI Trust 
 * Licence for the International Chemical Identifier (InChI) Software 
 * version 1.04, October 2011 ("IUPAC/InChI-Trust InChI Licence No.1.0") 
 * for more details.
 * 
 * You should have received a copy of the IUPAC/InChI Trust InChI 
 * Licence No. 1.0 with this library; if not, please write to:
 * 
 * The InChI Trust
 * c/o FIZ CHEMIE Berlin
 *
 * Franklinstrasse 11
 * 10587 Berlin
 * GERMANY
 *
 * or email to: ulrich@inchi-trust.org.
 * 
 */


/*
 *  The SHA-256 standard was published by NIST in 2002.
 *
 *  http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
 */

#ifndef _SHA2_H
#define _SHA2_H

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief          SHA-256 context structure
 */
typedef struct
{
    unsigned long total[2];     /*!< number of bytes processed  */
    unsigned long state[8];     /*!< intermediate digest state  */
    unsigned char buffer[64];   /*!< data block being processed */
}
sha2_context;

/**
 * \brief          SHA-256 context setup
 *
 * \param ctx      SHA-256 context to be initialized
 */
void sha2_starts( sha2_context *ctx );

/**
 * \brief          SHA-256 process buffer
 *
 * \param ctx      SHA-256 context
 * \param input    buffer holding the  data
 * \param ilen     length of the input data
 */
void sha2_update( sha2_context *ctx, unsigned char *input, int ilen );

/**
 * \brief          SHA-256 final digest
 *
 * \param ctx      SHA-256 context
 * \param output   SHA-256 checksum result
 */
void sha2_finish( sha2_context *ctx, unsigned char output[32] );

/**
 * \brief          Output = SHA-256( input buffer )
 *
 * \param input    buffer holding the  data
 * \param ilen     length of the input data
 * \param output   SHA-256 checksum result
 */
void sha2_csum( unsigned char *input, int ilen,
                unsigned char output[32] );

/**
 * \brief          Output = SHA-256( file contents )
 *
 * \param path     input file name
 * \param output   SHA-256 checksum result
 * \return         0 if successful, or 1 if fopen failed
 */
int sha2_file( char *path, unsigned char output[32] );

/**
 * \brief          Output = HMAC-SHA-256( input buffer, hmac key )
 *
 * \param key      HMAC secret key
 * \param keylen   length of the HMAC key
 * \param input    buffer holding the  data
 * \param ilen     length of the input data
 * \param output   HMAC-SHA-256 result
 */
void sha2_hmac( unsigned char *key, int keylen,
                unsigned char *input, int ilen,
                unsigned char output[32] );

/**
 * \brief          Checkup routine
 *
 * \return         0 if successful, or 1 if the test failed
 */
int sha2_self_test( void );

#ifdef __cplusplus
}
#endif

#endif /* sha2.h */