sha256.h

#if 0
Borrowed from scrypt-1.2.0 which includes the following copyright notice:

The code and documentation in this directory ("libcperciva") is distributed
under the following terms:

Copyright 2005-2014 Colin Percival.  All rights reserved.
Copyright 2014 Sean Kelly.  All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
#endif

#ifndef _SHA256_H_
#define _SHA256_H_

#include <stddef.h>
#include <stdint.h>

/*
 * Use #defines in order to avoid namespace collisions with anyone else's
 * SHA256 code (e.g., the code in OpenSSL).
 */
#define SHA256_Init libcperciva_SHA256_Init
#define SHA256_Update libcperciva_SHA256_Update
#define SHA256_Final libcperciva_SHA256_Final
#define SHA256_Buf libcperciva_SHA256_Buf
#define SHA256_CTX libcperciva_SHA256_CTX
#define HMAC_SHA256_Init libcperciva_HMAC_SHA256_Init
#define HMAC_SHA256_Update libcperciva_HMAC_SHA256_Update
#define HMAC_SHA256_Final libcperciva_HMAC_SHA256_Final
#define HMAC_SHA256_Buf libcperciva_HMAC_SHA256_Buf
#define HMAC_SHA256_CTX libcperciva_HMAC_SHA256_CTX

/* Context structure for SHA256 operations. */
typedef struct {
	uint32_t state[8];
	uint64_t count;
	uint8_t buf[64];
} SHA256_CTX;

/**
 * SHA256_Init(ctx):
 * Initialize the SHA256 context ${ctx}.
 */
void SHA256_Init(SHA256_CTX *);

/**
 * SHA256_Update(ctx, in, len):
 * Input ${len} bytes from ${in} into the SHA256 context ${ctx}.
 */
void SHA256_Update(SHA256_CTX *, const void *, size_t);

/**
 * SHA256_Final(digest, ctx):
 * Output the SHA256 hash of the data input to the context ${ctx} into the
 * buffer ${digest}.
 */
void SHA256_Final(uint8_t[32], SHA256_CTX *);

/**
 * SHA256_Buf(in, len, digest):
 * Compute the SHA256 hash of ${len} bytes from $in} and write it to ${digest}.
 */
void SHA256_Buf(const void *, size_t, uint8_t[32]);

/* Context structure for HMAC-SHA256 operations. */
typedef struct {
	SHA256_CTX ictx;
	SHA256_CTX octx;
} HMAC_SHA256_CTX;

/**
 * HMAC_SHA256_Init(ctx, K, Klen):
 * Initialize the HMAC-SHA256 context ${ctx} with ${Klen} bytes of key from
 * ${K}.
 */
void HMAC_SHA256_Init(HMAC_SHA256_CTX *, const void *, size_t);

/**
 * HMAC_SHA256_Update(ctx, in, len):
 * Input ${len} bytes from ${in} into the HMAC-SHA256 context ${ctx}.
 */
void HMAC_SHA256_Update(HMAC_SHA256_CTX *, const void *, size_t);

/**
 * HMAC_SHA256_Final(digest, ctx):
 * Output the HMAC-SHA256 of the data input to the context ${ctx} into the
 * buffer ${digest}.
 */
void HMAC_SHA256_Final(uint8_t[32], HMAC_SHA256_CTX *);

/**
 * HMAC_SHA256_Buf(K, Klen, in, len, digest):
 * Compute the HMAC-SHA256 of ${len} bytes from ${in} using the key ${K} of
 * length ${Klen}, and write the result to ${digest}.
 */
void HMAC_SHA256_Buf(const void *, size_t, const void *, size_t, uint8_t[32]);

/**
 * PBKDF2_SHA256(passwd, passwdlen, salt, saltlen, c, buf, dkLen):
 * Compute PBKDF2(passwd, salt, c, dkLen) using HMAC-SHA256 as the PRF, and
 * write the output to buf.  The value dkLen must be at most 32 * (2^32 - 1).
 */
void PBKDF2_SHA256(const uint8_t *, size_t, const uint8_t *, size_t,
    uint64_t, uint8_t *, size_t);

#endif /* !_SHA256_H_ */